document_title: Muscle contraction

question_text: muscles that assist in a movement are called

text: Muscle contraction

text: Types[edit]

text: Muscle contractions can be described based on two variables: force and length. Force itself can be differentiated as either tension or load. Muscle tension is the force exerted by the muscle on an object whereas a load is the force exerted by an object on the muscle.[1] When muscle tension changes without any corresponding changes in muscle length, the muscle contraction is described as isometric.[1][3][4][5] If the muscle length changes while muscle tension remains the same, then the muscle contraction is isotonic.[1][3][4][5] In an isotonic contraction, the muscle length can either shorten to produce a concentric contraction or lengthen to produce an eccentric contraction.[1][6] Furthermore, if the muscle length shortens, the contraction is concentric.[1][6] But if the muscle length lengthens, then the contraction is eccentric. In natural movements that underlie locomotor activity, muscle contractions are multifaceted as they are able to produce changes in length and tension in a time-varying manner.[7] Therefore, neither length nor tension is likely to remain constant when the muscle is active during locomotor activity.

text: Isometric contraction[edit]

text: An isometric contraction of a muscle generates tension without changing length.[1][3][4][5] An example can be found when the muscles of the hand and forearm grip an object; the joints of the hand do not move, but muscles generate sufficient force to prevent the object from being dropped.

text: Isotonic contraction[edit]

text: In isotonic contraction, the tension in the muscle remains constant despite a change in muscle length.[1][3][4][5] This occurs when a muscle's force of contraction matches the total load on the muscle.

text: Concentric contraction[edit]

text: In concentric contraction, muscle tension is sufficient to overcome the load, and the muscle shortens as it contracts.[8] This occurs when the force generated by the muscle exceeds the load opposing its contraction.

text: During a concentric contraction, a muscle is stimulated to contract according to the sliding filament theory. This occurs throughout the length of the muscle, generating a force at the origin and insertion, causing the muscle to shorten and changing the angle of the joint. In relation to the elbow, a concentric contraction of the biceps would cause the arm to bend at the elbow as the hand moved from the leg to the shoulder (a biceps curl). A concentric contraction of the triceps would change the angle of the joint in the opposite direction, straightening the arm and moving the hand towards the leg.

text: Eccentric contraction[edit]

text: In eccentric contraction, the tension generated is insufficient to overcome the external load on the muscle and the muscle fibers lengthen as they contract.[9] Rather than working to pull a joint in the direction of the muscle contraction, the muscle acts to decelerate the joint at the end of a movement or otherwise control the repositioning of a load. This can occur involuntarily (e.g., when attempting to move a weight too heavy for the muscle to lift) or voluntarily (e.g., when the muscle is 'smoothing out' a movement). Over the short-term, strength training involving both eccentric and concentric contractions appear to increase muscular strength more than training with concentric contractions alone.[10] However, exercise-induced muscle damage is also greater during lengthening contractions.[11]

text: During an eccentric contraction of the biceps muscle, the elbow starts the movement while bent and then straightens as the hand moves away from the shoulder. During an eccentric contraction of the triceps muscle, the elbow starts the movement straight and then bends as the hand moves towards the shoulder. Desmin, titin, and other z-line proteins are involved in eccentric contractions, but their mechanism is poorly understood in comparison to crossbridge cycling in concentric contractions.[9]

text: Though the muscle is doing a negative amount of mechanical work, (work is being done on the muscle), chemical energy (in fat, glucose or ATP) is nevertheless consumed, although less than would be consumed during a concentric contraction of the same force. For example, one expends more energy going up a flight of stairs than going down the same flight.

text: Muscles undergoing heavy eccentric loading suffer greater damage when overloaded (such as during muscle building or strength training exercise) as compared to concentric loading. When eccentric contractions are used in weight training, they are normally called negatives. During a concentric contraction, muscle fibers slide across each other, pulling the Z-lines together. During an eccentric contraction, the filaments slide past each other the opposite way, though the actual movement of the myosin heads during an eccentric contraction is not known. Exercise featuring a heavy eccentric load can actually support a greater weight (muscles are approximately 40% stronger during eccentric contractions than during concentric contractions) and also results in greater muscular damage and delayed onset muscle soreness one to two days after training. Exercise that incorporates both eccentric and concentric muscular contractions (i.e., involving a strong contraction and a controlled lowering of the weight) can produce greater gains in strength than concentric contractions alone.[10][12] While unaccustomed heavy eccentric contractions can easily lead to overtraining, moderate training may confer protection against injury.[10]

text: Eccentric contractions in movement[edit]

text: Eccentric contractions normally occur as a braking force in opposition to a concentric contraction to protect joints from damage. During virtually any routine movement, eccentric contractions assist in keeping motions smooth, but can also slow rapid movements such as a punch or throw. Part of training for rapid movements such as pitching during baseball involves reducing eccentric braking allowing a greater power to be developed throughout the movement.

text: Eccentric contractions are being researched for their ability to speed rehabilitation of weak or injured tendons. Achilles tendinitis [13][14] and patellar tendonitis [15] (also known as jumper's knee or patellar tendonosis) have been shown to benefit from high-load eccentric contractions.

text: Vertebrate animals[edit]

text: In vertebrate animals, there are three types of muscle tissues: skeletal, smooth, and cardiac. Skeletal muscle constitutes the majority of muscle mass in the body and is responsible for locomotor activity. Smooth muscle forms blood vessels, gastrointestinal tract, and other areas in the body that produce sustained contractions. Cardiac muscle make up the heart, which pumps blood. Skeletal and cardiac muscles are called striated muscle because of their striped appearance under a microscope, which is due to the highly organized alternating pattern of A bands and I bands.

text: Skeletal muscle[edit]

text: Excluding reflexes, all skeletal muscles contractions occur as a result of conscious effort originating in the brain. The brain sends electrochemical signals through the nervous system to the motor neuron that innervates several muscle fibers.[16] In the case of some reflexes, the signal to contract can originate in the spinal cord through a feedback loop with the grey matter. Other actions such as locomotion, breathing, and chewing have a reflex aspect to them: the contractions can be initiated both consciously or unconsciously.

text: Neuromuscular junction[edit]

text: A neuromuscular junction is a chemical synapse formed by the contact between a motor neuron and a muscle fiber.[17] It is the site in which a motor neuron transmits a signal to a muscle fiber to initiate muscle contraction. The sequence of events that results in the depolarization of the muscle fiber at the neuromuscular junction begins when an action potential is initiated in the cell body of a motor neuron, which is then propagated by saltatory conduction along its axon toward the neuromuscular junction. Once it reaches the terminal bouton, the action potential causes a Ca2+ ion influx into the terminal by way of the voltage-gated calcium channels. The Ca2+ influx causes synaptic vesicles containing the neurotransmitter acetylcholine to fuse with the plasma membrane, releasing acetylcholine into the synaptic cleft between the motor neuron terminal and the neuromuscular junction of the skeletal muscle fiber. Acetylcholine diffuses across the synapse and binds to and activates nicotinic acetylcholine receptors on the neuromuscular junction. Activation of the nicotinic receptor opens its intrinsic sodium/potassium channel, causing sodium to rush in and potassium to trickle out. As a result, the sarcolemma reverses polarity and its voltage quickly jumps from the resting membrane potential of -90mV to as high as +75mV as sodium enters. The membrane potential then becomes hyperpolarized when potassium exits and is then adjusted back to the resting membrane potential. This rapid fluctuation is called the end-plate potential [18] The voltage-gated ion channels of the sarcolemma next to the end plate open in response to the end plate potential. These voltage-gated channels are sodium and potassium specific and only allow one through. This wave of ion movements creates the action potential that spreads from the motor end plate in all directions.[18] If action potentials stop arriving, then acetylcholine ceases to be released from the terminal bouton. The remaining acetylcholine in the synaptic cleft is either degraded by active acetylcholine esterase or reabsorbed by the synaptic knob and none is left to replace the degraded acetylcholine.

text: Excitation-contraction coupling[edit]

text: Excitation–contraction coupling is the process by which a muscular action potential in the muscle fiber causes the myofibrils to contract.[19] In skeletal muscle, excitation–contraction coupling relies on a direct coupling between key proteins, the sarcoplasmic reticulum (SR) calcium release channel (identified as the ryanodine receptor, RyR) and voltage-gated L-type calcium channels (identified as dihydropyridine receptors, DHPRs). DHPRs are located on the sarcolemma (which includes the surface sarcolemma and the transverse tubules), while the RyRs reside across the SR membrane. The close apposition of a transverse tubule and two SR regions containing RyRs is described as a triad and is predominantly where excitation–contraction coupling takes place. Excitation–contraction coupling occurs when depolarization of skeletal muscle cell results in a muscle action potential, which spreads across the cell surface and into the muscle fiber's network of T-tubules, thereby depolarizing the inner portion of the muscle fiber. Depolarization of the inner portions activates dihydropyridine receptors in the terminal cisternae, which are in close proximity to ryanodine receptors in the adjacent sarcoplasmic reticulum. The activated dihydropyridine receptors physically interact with ryanodine receptors to activate them via foot processes (involving conformational changes that allosterically activates the ryanodine receptors). As the ryanodine receptors open, Ca2+ is released from the sarcoplasmic reticulum into the local junctional space, which then diffuses into the bulk cytoplasm to cause a calcium spark. Note that the sarcoplasmic reticulum has a large calcium buffering capacity partially due to a calcium-binding protein called calsequestrin. The near synchronous activation of thousands of calcium sparks by the action potential causes a cell-wide increase in calcium giving rise to the upstroke of the calcium transient. The Ca2+ released into the cytosol binds to Troponin C by the actin filaments, to allow crossbridge cycling, producing force and, in some situations, motion. The sarco/endoplasmic reticulum calcium-ATPase (SERCA) actively pumps Ca2+ back into the sarcoplasmic reticulum. As Ca2+ declines back to resting levels, the force declines and relaxation occurs.

text: Sliding filament theory[edit]

text: The sliding filament theory describes a process used by muscles to contract. It is a cycle of repetitive events that cause a thin filament to slide over a thick filament and generate tension in the muscle.[20] It was independently developed by Andrew Huxley and Rolf Niedergerke and by Hugh Huxley and Jean Hanson in 1954.[21][22] Physiologically, this contraction is not uniform across the sarcomere; the central position of the thick filaments becomes unstable and can shift during contraction. However the actions of elastic proteins such as titin are hypothesised to maintain uniform tension across the sarcomere and pull the thick filament into a central position.[23]

text: Crossbridge cycling[edit]

text: Crossbridge cycling is a sequence of molecular events that underlies the sliding filament theory. A crossbridge is a myosin projection, consisting of two myosin heads, that extends from the thick filaments.[1] Each myosin head has two binding sites: one for ATP and another for actin. The binding of ATP to a myosin head detaches myosin from actin, thereby allowing myosin to bind to another actin molecule. Once attached, the ATP is hydrolyzed by myosin, which uses the released energy to move into the "cocked position" whereby it binds weakly to a part of the actin binding site. The remainder of the actin binding site is blocked by tropomyosin.[24] With the ATP hydrolyzed, the cocked myosin head now contains ADP + Pi. Two Ca2+ ions bind to troponin C on the actin filaments. The troponin-Ca2+ complex causes tropomyosin to slide over and unblock the remainder of the actin binding site. Unblocking the rest of the actin binding sites allows the two myosin heads to close and myosin to bind strongly to actin.[24] The myosin head then releases the inorganic phosphate and initiates a power stroke, which generates a force of 2 pN. The power stroke moves the actin filament inwards, thereby shortening the sarcomere. Myosin then releases ADP but still remains tightly bound to actin. At the end of the power stroke, ADP is released from the myosin head, leaving myosin attached to actin in a rigor state until another ATP binds to myosin. A lack of ATP would result in the rigor state characteristic of rigor mortis. Once another ATP binds to myosin, the myosin head will again detach from actin and another crossbridges cycle occurs.

text: Crossbridge cycling is able to continue as long as there are sufficient amounts of ATP and Ca2+ in the cytoplasm.[24] Termination of crossbridge cycling can occur when Ca2+ is actively pumped back into the sarcoplasmic reticulum. When Ca2+ is no longer present on the thin filament, the tropomyosin changes conformation back to its previous state so as to block the binding sites again. The myosin ceases binding to the thin filament, and the muscle relaxes. The Ca2+ ions leave the troponin molecule in order to maintain the Ca2+ ion concentration in the sarcoplasm. The active pumping of Ca2+ ions into the sarcoplasmic reticulum creates a deficiency in the fluid around the myofibrils. This causes the removal of Ca2+ ions from the troponin. Thus, the tropomyosin-troponin complex again covers the binding sites on the actin filaments and contraction ceases.

text: Gradation of skeletal muscle contractions[edit]

text: The strength of skeletal muscle contractions can be broadly separated into twitch, summation, and tetanus. A twitch is a single contraction and relaxation cycle produced by an action potential within the muscle fiber itself.[25] The time between a stimulus to the motor nerve and the subsequent contraction of the innervated muscle is called the latent period, which usually takes about 10 ms and is caused by the time taken for nerve action potential to propagate, the time for chemical transmission at the neuromuscular junction, then the subsequent steps in excitation-contraction coupling.[26]

text: If another muscle action potential were to be produced before the complete relaxation of a muscle twitch, then the next twitch will simply sum onto the previous twitch, thereby producing a summation. Summation can be achieved in two ways:[27] frequency summation and multiple fiber summation. In frequency summation, the force exerted by the skeletal muscle is controlled by varying the frequency at which action potentials are sent to muscle fibers. Action potentials do not arrive at muscles synchronously, and, during a contraction, some fraction of the fibers in the muscle will be firing at any given time. In a typical circumstance, when a human is exerting a muscle as hard as he/she is consciously able, roughly one-third of the fibers in that muscle will be firing at once, though this ratio can be affected by various physiological and psychological factors (including Golgi tendon organs and Renshaw cells). This 'low' level of contraction is a protective mechanism to prevent avulsion of the tendon—the force generated by a 95% contraction of all fibers is sufficient to damage the body. In multiple fiber summation, if the central nervous system sends a weak signal to contract a muscle, the smaller motor units, being more excitable than the larger ones, are stimulated first. As the strength of the signal increases, more motor units are excited in addition to larger ones, with the largest motor units having as much as 50 times the contractile strength as the smaller ones. As more and larger motor units are activated, the force of muscle contraction becomes progressively stronger. A concept known as the size principle, allows for a gradation of muscle force during weak contraction to occur in small steps, which then become progressively larger when greater amounts of force are required.

text: Finally, if the frequency of muscle action potentials increases such that the muscle contraction reaches its peak force and plateaus at this level, then the contraction is a tetanus.

text: Length-tension relationship[edit]

text: Length-tension relationship relates the strength of an isometric contraction to the length of the muscle at which the contraction occurs. Muscles operate with greatest active tension when close to an ideal length (often their resting length). When stretched or shortened beyond this (whether due to the action of the muscle itself or by an outside force), the maximum active tension generated decreases.[28] This decrease is minimal for small deviations, but the tension drops off rapidly as the length deviates further from the ideal. Due to the presence of elastic proteins within a muscle cell (such as titin) and extracellular matrix, as the muscle is stretched beyond a given length, there is an entirely passive tension, which opposes lengthening. Combined together, there is a strong resistance to lengthening an active muscle far beyond the peak of active tension.

text: Force-velocity relationships[edit]

text: Force–velocity relationship relates the speed at which a muscle changes its length (usually regulated by external forces, such as load or other muscles) to the amount of force that it generates. Force declines in a hyperbolic fashion relative to the isometric force as the shortening velocity increases, eventually reaching zero at some maximum velocity. The reverse holds true for when the muscle is stretched – force increases above isometric maximum, until finally reaching an absolute maximum. This intrinsic property of active muscle tissue plays a role in the active damping of joints which are actuated by simultaneously-active opposing muscles. In such cases, the force-velocity profile enhances the force produced by the lengthening muscle at the expense of the shortening muscle. This favoring of whichever muscle returns the joint to equilibrium effectively increases the damping of the joint. Moreover, the strength of the damping increases with muscle force. The motor system can thus actively control joint damping via the simultaneous contraction (co-contraction) of opposing muscle groups. [29]

text: Smooth muscle[edit]

text: Smooth muscles can be divided into two subgroups: single-unit (unitary) and multi-unit. Single-unit smooth muscle cells can be found in the gut and blood vessels. Because these cells are linked together by gap junctions, they are able to contract as a syncytium. Single-unit smooth muscle cells contract myogenically, which can be modulated by the autonomic nervous system.

text: Unlike single-unit smooth muscle cells, multi-unit smooth muscle cells are found in the muscle of the eye and in the base of hair follicles. Multi-unit smooth muscle cells contract by being separately stimulated by nerves of the autonomic nervous system. As such, they allow for fine control and gradual responses, much like motor unit recruitment in skeletal muscle.

text: Mechanisms of smooth muscle contraction[edit]

text: The contractile activity of smooth muscle cells is influenced by multiple inputs such as spontaneous electrical activity, neural and hormonal inputs, local changes in chemical composition, and stretch.[1] This is in contrast to the contractile activity of skeletal muscle cells, which relies on a single neural input. Some types of smooth muscle cells are able to generate their own action potentials spontaneously, which usually occur following a pacemaker potential or a slow wave potential. These action potentials are generated by the influx of extracellular Ca2+, and not Na+. Like skeletal muscles, cytosolic Ca2+ ions are also required for crossbridge cycling in smooth muscle cells.

text: The two sources for cytosolic Ca2+ in smooth muscle cells are the extracellular Ca2+ entering through calcium channels and the Ca2+ ions that are released from the sarcoplasmic reticulum. The elevation of cytosolic Ca2+ results in more Ca2+ binding to calmodulin, which then binds and activates myosin light-chain kinase. The calcium-calmodulin-myosin light-chain kinase complex phosphorylates myosin on the 20 kilodalton (kDa) myosin light chains on amino acid residue-serine 19, initiating contraction and activating the myosin ATPase. Unlike skeletal muscle cells, smooth muscle cells lack troponin, even though they contain the thin filament protein tropomyosin and other notable proteins – caldesmon and calponin. Thus, smooth muscle contractions are initiated by the Ca2+-activated phosphorylation of myosin rather than Ca2+ binding to the troponin complex that regulates myosin binding sites on actin like in skeletal and cardiac muscles.

text: Termination of crossbridge cycling (and leaving the muscle in latch-state) occurs when myosin light chain phosphatase removes the phosphate groups from the myosin heads. Phosphorylation of the 20 kDa myosin light chains correlates well with the shortening velocity of smooth muscle. During this period, there is a rapid burst of energy utilization as measured by oxygen consumption. Within a few minutes of initiation, the calcium level markedly decreases, the 20 kDa myosin light chains' phosphorylation decreases, and energy utilization decreases; however, force in tonic smooth muscle is maintained. During contraction of muscle, rapidly cycling crossbridges form between activated actin and phosphorylated myosin, generating force. It is hypothesized that the maintenance of force results from dephosphorylated "latch-bridges" that slowly cycle and maintain force. A number of kinases such as rho kinase, ZIP kinase, and protein kinase C are believed to participate in the sustained phase of contraction, and Ca2+ flux may be significant.

text: Neuromodulation[edit]

text: Although smooth muscle contractions are myogenic, the rate and strength of their contractions can be modulated by the autonomic nervous system. Postganglionic nerve fibers of parasympathetic nervous system release the neurotransmitter acetylcholine, which binds to muscarinic acetylcholine receptors (mAChRs) on smooth muscle cells. These receptors are metabotropic, or G-protein coupled receptors that initiate a second messenger cascade. Conversely, postganglionic nerve fibers of the sympathetic nervous system release the neurotransmitters epinephrine and norepinephrine, which bind to adrenergic receptors that are also metabotropic. The exact effects on the smooth muscle depend on the specific characteristics of the receptor activated—both parasympathetic input and sympathetic input can be either excitatory (contractile) or inhibitory (relaxing).

text: Cardiac muscle[edit]

text: There are two types of cardiac muscle cells: autorhythmic and contractile. Autorhythmic cells do not contract, but instead set the pace of contraction for other cardiac muscle cells, which can be modulated by the autonomic nervous system. In contrast, contractile muscle cells (cardiomyocytes) constitute the majority of the heart muscle and are able to contract.

text: Excitation-contraction coupling[edit]

text: Unlike skeletal muscle, excitation–contraction coupling in cardiac muscle is thought to depend primarily on a mechanism called calcium-induced calcium release.[30] Though the proteins involved are similar, the L-type calcium channels and ryanodine receptors (RyRs) are not physically coupled. Instead, RyRs are activated by a calcium trigger, which is brought about by the flow of Ca2+through the L-type calcium channels. Furthermore, cardiac muscle tend to exhibit diad (or dyad) structures, rather than triads.

text: Excitation-contraction coupling in cardiac muscle cells occurs when an action potential is initiated by pacemaker cells in the sinoatrial node or Atioventricular node and conducted to all cells in the heart via gap junctions. The action potential travels along the surface membrane into T-tubules (the latter are not seen in all cardiac cell types) and the depolarisation causes extracellular Ca2+ to enter the cell via L-type calcium channels and possibly sodium-calcium exchanger (NCX) during the early part of the plateau phase. This Ca2+ influx causes a small local increase in intracellular Ca2+. The increase in Ca2+ is detected by ryanodine receptors in the membrane of the sarcoplasmic reticulum which releaes Ca2+ in a positive feedback physiological response. This positive feedback is known as calcium-induced calcium release [30] and gives rise to calcium sparks (Ca2+ sparks[31]). The spatial and temporal summation of ~30,000 Ca2+ sparks gives a cell-wide increase in cytoplasmic calcium concentration.[32] The increase in cytosolic calcium following the flow of calcium through the cell membrane and sarcoplasmic reticulum is moderated by calcium buffers which bind a large proportion of intracellular calcium. As a result, a large increase in total calcium leads to a relatively small rise in free Ca2+.[33]

text: The cytoplasmic calcium binds to Troponin C, moving the tropomyosin complex off the actin binding site allowing the myosin head to bind to the actin filament. From this point on, the contractile mechanism is essentially the same as for skeletal muscle (above). Briefly, using ATP hydrolysis, the myosin head pulls the actin filament toward the centre of the sarcomere.

text: Following systole, intracellular calcium is taken up by the sarco/endoplasmic reticulum ATPase (SERCA) pump back into the sarcoplasmic reticulum ready for the next cycle to begin. Calcium is also ejected from the cell mainly by the sodium-calcium exchanger (NCX) and, to a lesser extent, a plasma membrane calcium ATPase. Some calcium is also taken up by the mitochondria.[34] An enzyme, phospholamban, serves as a brake for SERCA. At low heart rates, phospholamban is active and slows down the activity of the ATPase so that Ca2+ does not have to leave the cell entirely. At high heart rates, phospholamban is phosphorylated and deactivated thus taking most Ca2+ from the cytoplasm back into the sarcoplasmic reticulum. Once again, calcium buffers moderate this fall in Ca2+concentration, permitting a relatively small decrease in free Ca2+concentration in response to a large change in total calcium. The falling Ca2+concentration allows the troponin complex to dissociate from the actin filament thereby ending contraction. The heart relaxes, allowing the ventricles to fill with blood and begin the cardiac cycle again.

text: Invertebrate animals[edit]

text: Circular and longitudinal muscles[edit]

text: In annelids such as earthworms and leeches, circular and longitudinal muscles cells form the body wall of these animals and are responsible for their movement.[35] In an earthworm that is moving through a soil, for example, contractions of circular and longitudinal muscles occur reciprocally while the coelomic fluid serves as a hydroskeleton by maintaining turgidity of the earthworm.[36] When the circular muscles in the anterior segments contract, the anterior portion of animal's body begins to constrict radially, which pushes the incompressible coelomic fluid forward and increasing the length of the animal. As a result, the front end of the animal moves forward. As the front end of the earthworm becomes anchored and the circular muscles in the anterior segments become relaxed, a wave of longitudinal muscle contractions passes backwards, which pulls the rest of animal's trailing body forward.[35][36] These alternating waves of circular and longitudinal contractions is called peristalsis, which underlies the creeping movement of earthworms.

text: Obliquely striated muscles[edit]

text: Invertebrates such as annelids, mollusks, and nematodes, possess obliquely striated muscles, which contain bands of thick and thin filaments that are arranged helically rather than transversely, like in vertebrate skeletal or cardiac muscles.[37] In bivalves, the obliquely striated muscles can maintain tension over long periods without using too much energy. Bivalves use these muscles to keep their shells closed.

text: Asynchronous muscles[edit]

text: Advanced insects such as wasps, flies, bees, and beetles possess asynchronous muscles that constitute the flight muscles in these animals.[37] These flight muscles are often called fibrillar muscles because they contain myofibrils that are thick and conspicuous.[38] A remarkable feature of these muscles is that they do not require stimulation for each muscle contraction. Hence, they are called asynchronous muscles because the number of contractions in these muscles do not correspond (or synchronize) with the number of action potentials. For example, a wing muscle of a tethered fly may receive action potentials at a frequency of 3 Hz but it is able to beat at a frequency of 120 Hz.[37] The high frequency beating is made possible because the muscles are connected to a resonant system, which is driven to a natural frequency of vibration.

text: History[edit]

text: In 1780, Luigi Galvani discovered that the muscles of dead frogs' legs twitched when struck by an electrical spark.[40] This was one of the first forays into the study of bioelectricity, a field that still studies the electrical patterns and signals in tissues such as nerves and muscles.

text: In 1952, the term excitation–contraction coupling was coined to describe the physiological process of converting an electrical stimulus to a mechanical response.[19] This process is fundamental to muscle physiology, whereby the electrical stimulus is usually an action potential and the mechanical response is contraction. Excitation–contraction coupling can be dysregulated in many diseases.Though excitation–contraction coupling has been known for over half a century, it is still an active area of biomedical research. The general scheme is that an action potential arrives to depolarize the cell membrane. By mechanisms specific to the muscle type, this depolarization results in an increase in cytosolic calcium that is called a calcium transient. This increase in calcium activates calcium-sensitive contractile proteins that then use ATP to cause cell shortening.

text: The mechanism for muscle contraction evaded scientists for years and requires continued research and updating.[41] The sliding filament theory was independently developed by Andrew F. Huxley and Rolf Niedergerke and by Hugh Huxley and Jean Hanson. Their findings were published as two consecutive papers published in the 22 May 1954 issue of Nature under the common theme "Structural Changes in Muscle During Contraction".[21][22]


document_title: History of the Panama Canal

question_text: when did the us start building the panama canal

question_tokens: when did the us start building the panama canal

root

text: History of the Panama Canal

text: French project[edit]

text: The idea of a canal across Central America was revived during the early 19th century. In 1819, the Spanish government authorized the construction of a canal and the creation of a company to build it.

tag: p

text: Although the project stalled for some time, a number of surveys were made between 1850 and 1875. They indicated that the two most-favorable routes were across Panama (then part of Colombia) and Nicaragua, with a third route across the Isthmus of Tehuantepec in Mexico another option. The Nicaraguan route was surveyed.

text: Conception[edit]

text: After the 1869 completion of the Suez Canal, France thought that an apparently-similar project to connect the Atlantic and Pacific Oceans could be carried out with little difficulty. In 1876 an international company, La Société internationale du Canal interocéanique, was created to undertake its construction; two years later, it obtained a concession from the Colombian government (since Panama was a Colombian province) to dig a canal across the isthmus.

text: Ferdinand de Lesseps, who was in charge of the Suez Canal construction, headed the project. His enthusiastic leadership and his reputation as the man who had built the Suez Canal persuaded speculators and ordinary citizens to invest nearly $400 million in the project.

text: However, despite his previous success de Lesseps was not an engineer. The Suez Canal, essentially a ditch dug through a flat, sandy desert, presented few challenges. Although Central America's mountainous spine has a low point in Panama, it is still 110 meters (360.9 ft) above sea level at its lowest crossing point. The sea-level canal proposed by de Lesseps would require a great deal of excavation through a variety of rock, rather than Suez' sand.

text: Less-obvious barriers were the rivers crossing the canal, particularly the Chagres (which flows strongly during the rainy season). Since the water would be a hazard to shipping if it drained into the canal, a sea-level canal would require the river's diversion.

text: The most serious problem was tropical disease, particularly malaria and yellow fever, whose methods of transmission were unknown at the time. The legs of hospital beds were placed in cans of water to keep insects from crawling up them, but the stagnant water was an ideal breeding place for mosquitoes (carriers of the diseases).

text: The project was plagued by a lack of engineering expertise. In May 1879, an international engineering congress led by de Lesseps convened in Paris. Of its 136 delegates, only 42 were engineers; the others were speculators, politicians and friends of de Lesseps.

text: He was convinced that a sea-level canal, dug through the mountainous spine of Central America, could be completed at least as easily as the Suez Canal. The engineering congress estimated the project's cost at $214 million; on February 14, 1880, an engineering commission revised the estimate to $168.6 million. De Lesseps reduced this estimate twice, with no apparent justification: on February 20 to $131.6 million and on March 1 to $120 million. The congress estimated seven or eight years as the time required to complete the canal; de Lesseps reduced this estimate to six years (the Suez Canal required ten).

text: The proposed sea-level canal would have a uniform depth of 9 meters (29.5 ft), a bottom width of 22 meters (72.2 ft) and a width at water level of about 27.5 meters (90.2 ft); the excavation estimate was 120,000,000 m3 (157,000,000 cu yd). A dam was proposed at Gamboa to control flooding of the Chagres River, with channels to drain water away from the canal. However, the Gamboa dam was later found impracticable and the Chagres River problem was left unsolved.

text: Construction[edit]

text: Construction of the canal began on January 1, 1881, with digging at Culebra beginning on January 22.[1] A large labor force was assembled, numbering about 40,000 in 1888 (nine-tenths of whom were afro-Caribbean workers from the West Indies). Although the project attracted good, well-paid French engineers, retaining them was difficult due to disease. The death toll from 1881 to 1889 was estimated at over 22,000, of whom as many as 5,000 were French citizens.[3]

text: By 1885 it had become clear to many that a sea-level canal was impractical, and an elevated canal with locks was preferable; de Lesseps resisted, and a lock canal plan was not adopted until October 1887. By this time increasing mortality rates, as well as financial and engineering problems coupled with frequent floods and mudslides, indicated that the project was in serious trouble. Work continued under the new plan until May 15, 1889, when the company went bankrupt and the project was suspended. After eight years the canal was about two-fifths completed, and about $234.8 million had been spent.

text: The company's collapse was a scandal in France, and the antisemitic Edouard Drumont exploited the role of two Jewish speculators in the affair. One hundred and four legislators were found to have been involved in the corruption, and Jean Jaurès was commissioned by the French parliament to conduct an inquiry which was completed in 1893.[2]

text: New Panama Canal Company[edit]

text: It soon became clear that the only way to recoup expenses for the stockholders was to continue the project. A new concession was obtained from Colombia, and in 1894 the Compagnie Nouvelle du Canal de Panama was created to finish the canal. To comply with the terms of the contract, work began immediately on the Culebra excavation while a team of engineers began a comprehensive study of the project. They eventually settled on a plan for a two-level, lock-based canal.

text: The new effort never gained traction, mainly because of US speculation that a canal through Nicaragua would render one through Panama useless. The most men employed on the new project was 3,600 (in 1896), primarily to comply with the terms of the concession and to maintain the existing excavation and equipment in saleable condition. The company had already begun looking for a buyer, with an asking price of $109 million.

text: In the US, a congressional Isthmian Canal Commission was established in 1899 to examine possibilities for a Central American canal and recommend a route. In November 1901, the commission reported that a US canal should be built through Nicaragua unless the French were willing to sell their holdings for $40 million. The recommendation became law on June 28, 1902, and the New Panama Canal Company was compelled to sell at that price.[3]

text: Results[edit]

text: Although the French effort was, to a large extent, doomed to failure from the beginning due to disease and a lack of understanding of the engineering difficulties, it was not entirely futile. The old and new companies excavated 59,747,638 m3 (78,146,960 cu yd) of material, of which 14,255,890 m3 (18,646,000 cu yd) was taken from the Culebra Cut. The old company dredged a channel from Panama Bay to the port at Balboa, and the channel dredged on the Atlantic side (known as the French canal) was useful for bringing in sand and stone for the locks and spillway concrete at Gatún.

text: Detailed surveys and studies (particularly those carried out by the new canal company) and machinery, including railroad equipment and vehicles, aided the later American effort. The French lowered the summit of the Culebra Cut along the canal route by five meters (17 ft), from 64 to 59 metres (210 to 194 ft). An estimated 22,713,396 m3 (29,708,000 cu yd) of excavation, valued at about $25.4 million, and equipment and surveys valued at about $17.4 million were usable by the Americans.[citation needed]

text: Nicaraguan canal[edit]

text: The 1848 discovery of gold in California and the rush of would-be miners stimulated US interest in building a canal between the oceans. In 1887, a United States Army Corps of Engineers regiment surveyed canal possibilities in Nicaragua. Two years later, the Maritime Canal Company was asked to begin a canal in the area and chose Nicaragua. The company lost money in the panic of 1893, and its work in Nicaragua ceased. In 1897 and 1899, the United States Congress charged a canal commission with researching possible construction; Nicaragua was chosen as the location both times.

text: Although the Nicaraguan canal proposal was made redundant by the American takeover of the French Panama Canal project, increases in shipping volume and ship sizes have revived interest in the project. A canal across Nicaragua accommodating post-Panamax ships or a rail link carrying containers between ports on either coast have been proposed.[citation needed]

text: United States[edit]

text: Theodore Roosevelt believed that a US-controlled canal across Central America was a vital strategic interest of the country. This idea gained wide circulation after the destruction of the USS Maine in Cuba on February 15, 1898. Reversing a Walker Commission decision in favor of a Nicaraguan canal, Roosevelt encouraged the acquisition of the French Panama Canal effort. George S. Morison was the only commission member who argued for the Panama location. The purchase of the French-held land for $40 million was authorized by the June 28, 1902 Spooner Act. Since Panama was then part of Colombia, Roosevelt began negotiating with that country to obtain the necessary rights. In early 1903 the Hay–Herrán Treaty was signed by both nations, but the Senate of Colombia failed to ratify the treaty.

text: Roosevelt implied to Panamanian rebels that if they revolted, the US Navy would assist their fight for independence. Panama declared its independence on November 3, 1903, and the USS Nashville impeded Colombian interference. The victorious Panamanians gave the United States control of the Panama Canal Zone on February 23, 1904, for $10 million in accordance with the November 18, 1903 Hay–Bunau-Varilla Treaty.

text: Takeover[edit]

text: The United States took control of the French property connected to the canal on May 4, 1904, when Lieutenant Jatara Oneel of the United States Army was presented with the keys during a small ceremony.[citation needed] The new Panama Canal Zone Control was overseen by the Isthmian Canal Commission (ICC) during construction.

text: The first step taken by the US government was to place all the canal workers under the new administration. The operation was maintained at minimum strength to comply with the canal concession and keep the machinery in working order. The US inherited a small workforce and an assortment of buildings, infrastructure and equipment, much of which had been neglected for fifteen years in the humid jungle environment. There were no facilities in place for a large workforce, and the infrastructure was crumbling.

text: Cataloguing assets was a large job; it took many weeks to card-index available equipment. About 2,150 buildings had been acquired,[4] many of which were uninhabitable; housing was an early problem, and the Panama Railway was in a state of decay. However, much equipment (such as locomotives, dredges and other floating equipment) was still serviceable.

text: Although chief engineer John Findley Wallace was pressured to resume construction, red tape from Washington stifled his efforts to obtain heavy equipment and caused friction between Wallace and the ICC. He and chief sanitary officer William C. Gorgas were frustrated by delay, and Wallace resigned in 1905. He was replaced by John Frank Stevens, who arrived on July 26, 1905. Stevens quickly realized that serious investment in infrastructure was necessary and determined to upgrade the railway, improve sanitation in Panama City and Colón, renovate the old French buildings and build hundreds of new ones for housing. He then began the difficult task of recruiting the large labor force required for construction. Stevens' approach was to press ahead first and obtain approval later. He improved drilling and dirt-removal equipment at the Culebra Cut for greater efficiency, revising the inadequate provisions in place for soil disposal.

text: No decision had been made about whether the canal should be a lock or a sea-level one; the ongoing excavation would be useful in either case. In late 1905, President Roosevelt sent a team of engineers to Panama to investigate the relative merits of both types in cost and time. Although the engineers voted eight to five in favor of a sea-level canal, Stevens and the ICC opposed the plan; Stevens' report to Roosevelt was instrumental in convincing the president of the merits of a lock canal and Congress concurred. In November 1906 Roosevelt visited Panama to inspect the canal's progress, the first trip outside the United States by a sitting president.

text: Whether contract employees or government workers would build the canal was controversial. Bids for the canal's construction were opened in January 1907, and Knoxville, Tennessee-based contractor William J. Oliver was the low bidder. Stevens disliked Oliver, and vehemently opposed his choice. Although Roosevelt initially favored the use of a contractor, he eventually decided that army engineers should carry out the work[4] and appointed Major George Washington Goethals as chief engineer (under Stevens' direction) in February 1907. Stevens, frustrated by government inaction and the army involvement, resigned and was replaced by Goethals.[5]

text: Workforce[edit]

text: The US relied on a stratified workforce to build the canal. High-level engineering jobs, clerical positions, skilled labor and jobs in supporting industries were generally reserved for white Americans, with manual labor primarily by cheap immigrant labor. These jobs were initially filled by Europeans, primarily from Spain, Italy and Greece, many of whom were radical and militant due to political turmoil in Europe. The US then decided to recruit primarily from the British and French West Indies, and these workers provided most of the manual labor on the canal.[6]

text: Living conditions[edit]

text: The Canal Zone originally had minimal facilities for entertainment and relaxation for the canal workers apart from saloons; as a result, alcohol abuse was a great problem. The inhospitable conditions resulted in many American workers returning home each year.

text: A program of improvements was implemented. Clubhouses were built, managed by the YMCA, with billiard, assembly and reading rooms, bowling alleys, darkrooms for camera clubs, gymnastic equipment, ice cream parlors, soda fountains and a circulating library. Member dues were ten dollars a year, with the remaining upkeep (about $7,000 at the larger clubhouses) paid by the ICC. The commission built baseball fields and arranged rail transportation to games; a competitive league soon developed. Semimonthly Saturday-night dances were held at the Hotel Tivoli, which had a spacious ballroom.

text: These measures influenced life in the Canal Zone; alcohol abuse fell, with saloon business declining by 60 percent.[citation needed] The number of workers leaving the project each year dropped significantly.

text: US construction[edit]

text: The work done thus far was preparation, rather than construction. By the time Goethals took over, the construction infrastructure had been created or overhauled and expanded from the French effort and he was soon able to begin construction in earnest.

text: Goethals divided the project into three divisions: Atlantic, Central and Pacific. The Atlantic Division, under Major William L. Sibert, was responsible for construction of the breakwater at the entrance to Limon Bay, the Gatún locks and their 5.6 km (3.5 mi) approach channel, and the Gatun Dam. The Pacific Division (under Sydney B. Williamson, the only civilian division head) was responsible for the Pacific entrance to the canal, including a 4.8 km (3.0 mi) breakwater in Panama Bay, the approach channel, and the Miraflores and Pedro Miguel locks and their associated dams. The Central Division, under Major David du Bose Gaillard, was responsible for everything in between. It had arguably the project's greatest challenge: excavating the Culebra Cut (known as the Gaillard Cut from 1915 to 2000), which involved cutting 8 miles (13 km) through the continental divide down to 12 meters (40 ft) above sea level.

text: By August 1907, 765,000 m³ (1,000,000 cubic yards) per month was being excavated; this set a record for the rainy season; soon afterwards this doubled, before increasing again. At the peak of production, 2,300,000 m³ (3,000,000 cubic yards) were being excavated per month (the equivalent of digging a Channel Tunnel every 3½ months).[citation needed]

text: Culebra Cut[edit]

text: One of the greatest barriers to a canal was the continental divide, which originally rose to 110 metres (360.9 ft) above sea level at its highest point. The effort to cut through this barrier of rock was one of the greatest challenges faced by the project.

text: Goethals arrived at the canal with Major David du Bose Gaillard of the US Army Corps of Engineers. Gaillard was placed in charge of the canal's Central Division, which stretched from the Pedro Miguel locks to the Gatun Dam, and dedicated himself to getting the Culebra Cut (as it was then known) excavated.

text: The scale of the work was massive. Six thousand men worked in the cut, drilling holes in which a total of 27,000 t (60,000,000 lb) of dynamite were placed to break up the rock (which was then removed by as many as 160 trains per day). Landslides were frequent, due to the oxidation and weakening of the rock's underlying iron strata. Although the scale of the job and the frequent, unpredictable slides generated chaos, Gaillard provided quiet, clear-sighted leadership.

text: On May 20, 1913, Bucyrus steam shovels made a passage through the Culebra Cut at the level of the canal bottom. The French effort had reduced the summit to 59 metres (193.6 ft) over a relatively narrow width; the Americans had lowered this to 12 metres (39.4 ft) above sea level over a greater width, and had excavated over 76,000,000 m3 (99,000,000 cu yd) of material. About 23,000,000 m3 (30,000,000 cu yd) of this material in addition to the planned excavation, in the form of landslides. Dry excavation ended on September 10, 1913; a January slide had added 1,500,000 m3 (2,000,000 cu yd) of earth, but it was decided that this loose material would be removed by dredging when the cut was flooded.

text: Dams[edit]

text: Two artificial lakes are key parts of the canal: Gatun and Miraflores Lakes. Four dams were constructed to create them. Two small dams at Miraflores impound Miraflores Lake, and a dam at Pedro Miguel encloses the south end of the Culebra Cut (essentially an arm of Lake Gatun). The Gatun Dam is the main dam blocking the original course of the Chagres River, creating Gatun Lake.

text: The Miraflores dams are an 825-metre (2,707 ft) earth dam connecting the Miraflores Locks in the west and a 150-metre (492 ft) concrete spillway dam east of the locks. The concrete dam has eight floodgates, similar to those on the Gatun spillway. The earthen, 430-metre (1,411 ft) Pedro Miguel dam extends from a hill in the west to the lock. Its face is protected by rock riprap at the water level. The largest and most challenging of the dams is the Gatun Dam. This earthen dam, 640 metres (2,100 ft) thick at the base and 2,300 metres (7,546 ft) long along the top, was the largest of its kind in the world when the canal opened.[citation needed]

text: Locks[edit]

text: Building the locks began with the first concrete laid at Gatun on August 24, 1909. The Gatun locks are built into a cutting into a hill bordering the lake, requiring the excavation of 3,800,000 m3 (4,970,212 cu yd) of material (mostly rock). The locks were made of 1,564,400 m3 (2,046,158 cu yd) of concrete, with an extensive system of electric railways and cable cars transporting concrete to the lock-construction sites.

text: The Pacific-side locks were finished first: the single flight at Pedro Miguel in 1911, and Miraflores in May 1913. The seagoing tugboat Gatun, an Atlantic-entrance tug used to haul barges, traversed the Gatun locks on September 26, 1913. The trip was successful, although the valves were controlled manually; the central control board was not yet ready.

text: Opening[edit]

text: On October 10, 1913, the dike at Gamboa which had kept the Culebra Cut isolated from Gatun Lake was demolished; the detonation was made telegraphically by President Woodrow Wilson in Washington. On January 7, 1914, the Alexandre La Valley, an old French crane boat, became the first ship to make a complete transit of the Panama Canal under its own steam after working its way across during the final stages of construction.

text: As construction wound down, the canal team began to disperse. Thousands of workers were laid off, and entire towns were disassembled or demolished. Chief sanitary officer William C. Gorgas, who left to fight pneumonia in the South African gold mines, became surgeon general of the Army. On April 1, 1914 the Isthmian Canal Commission disbanded, and the zone was governed by a Canal Zone Governor; the first governor was George Washington Goethals.

text: Although a large celebration was planned for the canal's opening, the outbreak of World War I forced the cancellation of the main festivities and it became a modest local affair. The Panama Railway steamship SS Ancon, piloted by Captain John A. Constantine (the canal's first pilot), made the first official transit on August 15, 1914. With no international dignitaries in attendance, Goethals followed the Ancon's progress by railroad.

text: Summary[edit]

text: The canal was a technological marvel and an important strategic and economic asset to the US. It changed world shipping patterns, removing the need for ships to navigate the Drake Passage and Cape Horn. The canal saves a total of about 7,800 miles (12,600 km) on a sea trip from New York to San Francisco.

text: Its anticipated military significance of the canal was proven during World War II, when the canal helped restore the devastated United States Pacific Fleet.[7] Some of the largest ships the United States had to send through the canal were aircraft carriers, particularly Essex class; they were so large that although the locks could accommodate them, the lampposts along the canal had to be removed.

text: The Panama Canal cost the United States about $375 million, including $10 million paid to Panama and $40 million paid to the French company. Although it was the most expensive construction project in US history to that time, it cost about $23 million less than the 1907 estimate despite landslides and an increase in the canal's width. An additional $12 million was spent on fortifications.

text: A total of over 75,000 people worked on the project; at the peak of construction, there were 40,000 workers. According to hospital records, 5,609 workers died from disease and accidents during the American construction era.[citation needed]

text: A total of 182,610,550 m3 (238,845,582 cu yd) of material was excavated in the American effort, including the approach channels at the canal ends. Adding the work by the French, the total excavation was about 204,900,000 m3 (268,000,000 cu yd) (over 25 times the volume excavated in the Channel Tunnel project).[citation needed]

text: Of the three presidents whose terms spanned the construction period, Theodore Roosevelt is most associated with the canal and Woodrow Wilson presided over its opening. However, William Howard Taft may have given the canal its greatest impetus for the longest time. Taft visited Panama five times as Roosevelt's secretary of war and twice as president. He hired John Stevens and later recommended Goethals as Stevens' replacement. Taft became president in 1909, when the canal was half finished, and was in office for most of the remainder of the work. However, Goethals later wrote: "The real builder of the Panama Canal was Theodore Roosevelt".[citation needed]

text: The following words by Roosevelt are displayed in the rotunda of the canal's administration building in Balboa:[citation needed]

text: It is not the critic who counts, not the man who points out how the strong man stumbled, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena; whose face is marred by dust and sweat and blood; who strives valiantly, who errs and comes short again and again; who knows the great enthusiasms, the great devotions, and spends himself in a worthy cause; who, at the best, knows in the end the triumph of high achievement; and who, at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who know neither victory nor defeat.

text: David du Bose Gaillard died of a brain tumor in Baltimore on December 5, 1913, at age 54. Promoted to colonel only a month earlier, Gaillard never saw the opening of the canal whose creation he directed. The Culebra Cut (as it was originally known) was renamed the Gaillard Cut on April 27, 1915, in his honor. A plaque commemorating Gaillard's work stood over the cut for many years; in 1998 it was moved to the administration building, near a memorial to Goethals.

text: Third-lane plans[edit]

text: As the situation in Europe deteriorated during the late 1930s, the US again became concerned about its ability to move warships between the oceans. The largest US battleships already had problems with the canal locks, and there were concerns about the locks being incapacitated by bombing.[8][9]

text: These concerns led Congress to pass a resolution on May 1, 1936, authorizing a study of improving the canal's defenses against attack and expanding its capacity to handle large vessels. A special engineering section was created on July 3, 1937, to carry out the study. The section reported to Congress on February 24, 1939, recommending work to protect the existing locks and the construction of a new set of locks capable of carrying larger vessels than the existing locks could accommodate. On August 11, Congress authorized the work.

text: Three new locks were planned, at Gatún, Pedro Miguel and Miraflores, parallel to the existing locks with new approach channels. The new locks would add a traffic lane to the canal, with each chamber 1,200 ft (365.76 m) long, 140 ft (42.67 m) wide and 45 ft (13.72 m) deep. They would be 1⁄2 mi (805 m) east of the existing Gatún locks and 1⁄4 mi (402 m) west of the Pedro Miguel and Miraflores locks.

text: The first excavations for the new approach channels at Miraflores began on July 1, 1940, following the passage by Congress of an appropriations bill on June 24, 1940. The first dry excavation at Gatún began on February 19, 1941. Considerable material was excavated before the project was abandoned, and the approach channels can still be seen paralleling the original channels at Gatún and Miraflores.

text: In 2006, the Autoridad del Canal de Panamá (the Panama Canal Authority, or ACP) proposed a plan creating a third lane of locks using part of the abandoned 1940s approach canals. Following a referendum, work began in 2007 and the expanded canal began commercial operations on June 26, 2016. After a two-year delay, the new locks allow the transit of Panamax ships (which have a greater cargo capacity than the original locks can handle). The first ship to cross the canal through the third set of locks was a Panamax container ship, the Chinese-owned Cosco Shipping Panama. The cost of the expansion was estimated at $5.25 billion.[2]

text: Transfer to Panama[edit]

text:
Statement on the Panama Canal treaty signing

Play media

Jimmy Carter's speech upon signing the Panama Canal treaty, September 7, 1977

Statement on the Panama Canal treaty signing

Audio-only version

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tag: table

text: After construction, the canal and the Canal Zone surrounding it were administered by the United States. On September 7, 1977, US President Jimmy Carter signed the Torrijos-Carter Treaty setting in motion the process of transferring control of the canal to Panama. The treaty became effective on October 1, 1979, providing for a 20-year period in which Panama would have increasing responsibility for canal operations before complete US withdrawal on December 31, 1999. Since then, the canal has been administered by the Panama Canal Authority (Autoridad de Canal de Panama, or ACP).

text: The treaty was controversial in the US, and its passage was difficult. The controversy was largely generated by contracts to manage two ports, at either end of the canal, which were awarded by Panama to Hong Kong-based conglomerate Hutchison Whampoa. According to US Republicans, the company has close ties to the Chinese government and the Chinese military.[10] However, the United States Department of State said that it found no evidence of connections between Hutchison Whampoa and Beijing.[11] Some Americans were wary of placing the strategic waterway under the protection of Panamanian security forces.[12]

text: Although concerns existed in the US and the shipping industry about the canal after the transfer, Panama has exercised good stewardship.[13] According to ACP figures, canal income increased from $769 million in 2000 (the first year under Panamanian control) to $1.4 billion in 2006.[citation needed] Traffic through the canal increased from 230 million tons in 2000 to nearly 300 million tons in 2006. The number of accidents has decreased from an average of 28 per year in the late 1990s to 12 in 2005. Transit time through the canal averages about 30 hours, about the same as during the late 1990s. Canal expenses have increased less than revenue, from $427 million in 2000 to $497 million in 2006. On October 22, 2006, Panamanian citizens approved a referendum to expand the canal.

text: Former US Ambassador to Panama Linda Watt, who served from 2002 to 2005, said that the canal operation in Panamanian hands has been "outstanding". "The international shipping community is quite pleased", Watt added.[14]


document_title: Speed of the Sound of Loneliness

question_text: who wrote the song speed of the sound of loneliness

text: Speed of the Sound of Loneliness

text: This article does not cite any sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (September 2016) (Learn how and when to remove this template message)

text: "Speed of the Sound of Loneliness" is a song written by John Prine. It was released as a track on Prine's 1986 album German Afternoons.

text: The song gained further fame with a duet recording by Prine and American singer Nanci Griffith in the latter's 1993 album Other Voices, Other Rooms and the release of the track as a single.

text: The song has been covered by many, notably Kim Carnes who released it as a single from her 1988 album View from the House and by the English band Alabama 3 on their 1997 album Exile on Coldharbour Lane and  American singer/songwriter Jeffrey Foucault in 2009 in his Prine tribute album Shoot the Moon Right Between the Eyes. Scottish singer Roddy Woomble recorded a live version in 2014 in his album Live at Kings Place.

text:
hidevteJohn PrineStudio albums
John Prine (1971)
Diamonds in the Rough (1972)
Sweet Revenge (1973)
Common Sense (1975)
Bruised Orange (1978)
Pink Cadillac (1979)
Storm Windows (1980)
Aimless Love (1984)
German Afternoons (1986)
The Missing Years (1991)
A John Prine Christmas (1994)
Lost Dogs and Mixed Blessings (1995)
In Spite of Ourselves (1999)
Souvenirs (2000)
Fair & Square (2005)
Standard Songs for Average People (with Mac Wiseman) (2007)
For Better, or Worse (2016)
The Tree of Forgiveness (2018)
Live albums
John Prine Live (1988)
Live on Tour (1997)
In Person & On Stage (2010)
Compilation albums
Prime Prine: The Best of John Prine (1976)
Great Days: The John Prine Anthology (1993)
Songs
"Sam Stone"
"Paradise"
"Your Flag Decal Won't Get You Into Heaven Anymore"
"Angel from Montgomery"
"The Great Compromise"
"Speed of the Sound of Loneliness"
Related
Oh Boy Records
John Prine - Live from Sessions at West 54th
Broken Hearts & Dirty Windows: Songs of John Prine

text: 1986 songs1993 singlesJohn Prine songsNanci Griffith songsSongs written by John Prine

tag: ul

text: Articles lacking sources from September 2016All articles lacking sources


document_title: Civil Services of India

question_text: who introduced the system of civil services in india

text: Civil Services of India

text: History[edit]

text:
“

If a responsible government is to be established in India, there will be a far greater need than is even dreamt of at present for persons to take part in public affairs in the legislative assemblies and elsewhere and for this reason the more Indians we can employ in the public service the better. Moreover, it would lessen the burden of Imperial responsibilities if a body of capable Indian administrators could be produced..

”

— Regarding the importance of Indianising Civil Services, Montagu–Chelmsford Reforms[7]

text: Warren Hastings laid the foundation of civil service and Charles Cornwallis reformed, modernised and rationalised it. Hence, Charles Cornwallis is known as the 'Father of Civil Service in India'. He introduced Covenanted Civil Services (Higher Civil Services) and Uncovenanted Civil Services (Lower Civil Services).

text: The present civil services of India is mainly based on the pattern of the former Indian Civil Service of British India. The civil services were divided into two categories - covenanted and uncovenanted. The covenanted civil service consisted of only Europeans (i.e., English personnel) occupying the higher posts in the government. The uncovenanted civil service was solely introduced to facilitate the entry of Indians at the lower rung of the administration.[8][9]

text: With the passing of the Government of India Act 1919, the Imperial Services headed by the Secretary of State for India, were split into two – All India Services and Central Services.[10]

text: The All India and Central Services (Group A) were designated as Central Superior Services as early as 1924.[11] From 1924 to 1934, Administration in India consisted of 10 All India Services and 5 central departments, all under the control of Secretary of State for India, and 3 central departments under joint Provincial and Imperial Control.[11]

text: Modern era[edit]

text: The present modern civil service was formed after the partition of India in 1947. It was Sardar Patel's vision that the Civil Service should strengthen cohesion and national unity. The values of integrity, impartiality and merit remain the guiding principles of Indian civil services.[citation needed]

text: By the early 21st century, Indian civil servants have been colloquially called "babus",[12] while Indian bureaucracy is called "babudom", as in the "rule of babus", especially in Indian media.[13][14][15]

text: Ministry of Personnel, Public Grievances and Pensions located in New Delhi is unofficially the "Ministry of Civil Services" in India. The Ministry is responsible for training, reforms and pension for the civil service system in India.

text: Constitutional provision for All-India Services[edit]

text: The constitution under Article 312[16] provides for All India Civil Services branches to be set up by giving the power to the Rajya Sabha (upper house of the Parliament of India) to resolve by a two-thirds majority to establish new all-India services. The Indian Administrative Service, Indian Police Service and Indian Forest Service are set up under this constitutional provision.[17]

text: Power, purpose and responsibilities[edit]

text: The responsibility of the civil services is to run the administration of India. The country is managed through a number of Central Government agencies in accordance with the policy directions given by the ministries.

text: The members of the civil services are represented as administrators in the central government and state government; emissaries in the foreign missions/embassies; as tax collectors and revenue commissioners; as civil service commissioned police officers; as permanent representative(s) and employees in the United Nations and its agencies and as Chairman, Managing Director, full-time functional Director/Member of the Board of Management of various Public Sector Undertakings/ Enterprises, Corporations, Banks and financial institutions. Civil servants are employed to various agencies of India and can also be appointed as advisors or special duty officers or private secretaries to ministers of the Union and the State Government.[18][19]

text: All appointments in the rank of Joint Secretary to Government of India and above, other major appointments, empanelment and extension of tenure is done by the Appointments Committee of the Cabinet. However, all appointments in the ranks below Joint Secretary in the federal government are done by the Civil Services Board. Civil servants are the actual laws and policies' makers in the country. They work on behalf of the elected government and cannot publicly show their disinterest or disapproval for the elected government. It is mandatory for them to form certain rules and policies according to the government's views and interests, but additionally they cannot be removed by any state or central government, but can only be retired.

text: Governance[edit]

text: Head of the Civil Services[edit]

text: The highest ranking civil servant is the Cabinet Secretary. He is ex-officio Chairman of the Civil Services Board; the chief of the Indian Administrative Service and head of all civil services under the rules of business of the Government of India. He also holds the 11th position in the Order of Precedence of India.

text: The position holder is accountable for ensuring that the Civil Service is equipped with the skills and capability to meet the everyday challenges it faces and that civil servants work in a fair and decent environment.

text: Values and codes[edit]

text: Values[edit]

text: A member of the civil service in discharge of his/her functions is to be guided by maintaining absolute integrity, allegiance to the constitution and the law of the nation, patriotism, national pride, devotion to duty, honesty, impartiality and transparency.[20]

text: Codes[edit]

text: The Government of India promotes values and a certain standard of ethics of requiring and facilitating every civil servant:[20]

text:
To discharge official duty with responsibility, honesty, accountability and without discrimination.
To ensure effective management, leadership development and personal growth.
To avoid misuse of official position or information.
To serve as instruments of good governance and foster social economic development.

text: Construction[edit]

text: The Higher Civil Services of India can be classified into two types - the All India Services and the Central Civil Services (Group A). The recruits are university graduates (or above) selected through a rigorous system of examinations: Civil Services Examination, Engineering Services Examination, Combined Geo-Scientist and Geologist Examination, I.E.S./I.S.S. Examination, Combined Medical Services Examination, Central Armed Police Forces of Union Public Service Commission (UPSC) for Group A posts.

text: All India Services[edit]

text: All appointments to All India Civil Services are made by the President of India.

text:
Indian Administrative Service (IAS)
Indian Forest Service (IFS)
Indian Police Service (IPS)
Indian Medical Service (IMS)
Indian Engineering Service (IEng.S)
Indian Statistical Service (IMS)
Indian Economic Service (IES)

text: Central Services (Group A)[edit]

text:
The Central Civil Services (Group A) are concerned with the administration of the Union Government.[21]
All appointments to Central Civil Services (Group A) are made by the President of India.

text:
Archaeological Service, Group 'A'.
Botanical Survey of India, Group 'A'.
Central Architects Service, Group 'A'.
Central Engineering (Civil) Group 'A' Service.
Central Engineering (Electrical and Mechanical) Group 'A' Service.
Central Health Service, Group 'A'.
Central Revenues Chemical Service, Group 'A'.
Central Secretariat Service-
(a) Selection Grade
(b) Grade I.

General Central Service, Group 'A'.
Geological Survey of India, Group 'A'.
Indian Audit and Accounts Service, Group 'A'.
Indian Civil Accounts Service.
Indian Defence Accounts Service
Indian Foreign Service, Group 'A'.
Indian Meteorological Service, Group 'A'.
Indian Postal Service, Group 'A'.
Indian Posts and Telegraphs Traffic Service, Group 'A'.
Indian Revenue Service -
(a) Customs Branch (Indian Customs Service, Group 'A')
(b) Central Excise Branch (Central Excise Service, Group 'A')
(c) Income Tax Branch (Income Tax Service, Group 'A')

Indian Salt Service, Group 'A'.
Mercantile Marine Training Ship Service, Group 'A'.
Directorate General of Mines Safety, Group 'A'.
Overseas Communications Service, Group 'A'.
Survey of India, Group 'A'.
Indian Telecommunication Service, Group 'A'.
Zoological Survey of India, Group 'A'.

Indian Frontier Administrative Service, Group 'A'-
(a) Grade I
(b) Grade II

Central Legal Service (Grades I, II, III and IV)
Railway Inspectorate Service, Group 'A'
Indian Foreign Service, Branch (B) (erstwhile)-
(a) General Cadre, Grade I
(b) General Cadre, Grade II

Delhi and Andaman and Nicobar Islands Civil Service, Grade I.
Delhi and Andaman and Nicobar Islands Police Service, Grade I.
Indian Inspection Service, Group 'A'
Indian Supply Service, Group 'A'
Central Information Service-
(a) Selection Grade
(b) Senior Administrative Grade
(c) Junior Administrative Grade
(d) Grade I
(e) Grade II

Indian Statistical Service
Indian Economic Service
Telegraph Traffic Service, Group 'A'
Central Water Engineering Service, Group 'A'
Central Power Engineering Service, Group 'A'
Company Law Board Service
Labour Officers of the Central Pool, Group 'A'
Central Engineering Service (Roads), Group 'A'
Indian Posts and Telegraphs Accounts and Finance Service, Group 'A'
Indian Broadcasting (Engineers) Service
Central Trade Service, Group 'A'
Armed Forces Headquarters Civil Services (Group 'A')
Central Secretariat Official Language Service (Group 'A')

text: Central Services (Group B)[edit]

text:
For Group B posts, the Combined Graduate Level Examination (CGLE) is conducted by the Staff Selection Commission (SSC).[a][22]
All appointments to Group B are made by the authorities specified by a general or special order of the President.

text:
Armed Forces Headquarters Civil Services
Botanical Survey of India, Group 'B'
Central Electrical Engineering Service, Group 'B'
Central Engineering Service, Group 'B'
Central Excise Service, Group ‘B’
Central Health Service, Group ‘B’
Central Power Engineering Service, Group ‘B’
Central Secretariat Official Language Service, Group ‘B’
Central Secretariat Service, Group 'B' (Section and Assistant Section Grade officers only)
Central Secretariat Stenographers’ Service, (Grade I, Grade II and Selection Grade officers only)
Customs Appraisers Service, Group ‘B’- (Principal Appraisers and Head Appraisers)
Customs Preventive Service, Group ‘B’ – (Chief Inspectors)
Defence Secretariat Service
DANICS, Grade II
DANIPS, Grade II
Geological Survey of India, Group 'B'
Indian Foreign Service, Group ‘B’ - (General Cadre, Grade I and General Cadre, Grade II only)
Indian Posts and Telegraphs Accounts and Finance Service, Group ‘B’ Telecommunication Wing.
Indian Posts & Telegraphs Accounts & Finance Service, Postal Wing, Group ‘B’
Income Tax Service, Group ‘B’
Indian Salt Service, Group ‘B’
India Meteorological Service, Group ‘B'
Survey of India, Group 'B'
Postal Superintendents’ Service, Group ‘B’
Postmasters’ Service, Group ‘B’
Railway Board Secretariat Service, Group ‘B’
Telecommunication Engineering Service, Group ‘B’
Telegraphs Traffic Service, Group ‘B
Zoological Survey of India, Group 'B'

text: State Services (Group A)[edit]

text:
The State Civil Services examinations and recruitment are conducted by the individual states public service commissions in India. These services are feeder services of All India Services.
All appointments to State Services (Group A) are made by the Governors of States.

text: All state civil and Administrative services in India above the rank of Deputy Collector are group A service. The officers of following services are later promoted to IAS.

text:
Andhra Pradesh State Civil Service (Executive Branch)
Arunachal Pradesh Civil Service-Executive Branch (APCS) officer promoted to IAS.
Assam Civil Service (ACS)
Bihar Administrative Service (BAS)
Goa Civil Service (GCS)
State Administrative Service (SAS)
State Civil Service (SCS)
Gujarat Administrative Service (GAS)
Haryana Civil Service (HCS)
Himachal Pradesh Administrative Service (HPAS)
Jharkhand Administrative Service (JAS)
Kashmir Administrative Service (KAS)
Karnataka Administrative Service (KAS)

Kerala Administrative Service (KAS)
Manipur Civil Service (MCS)
Mizoram Civil Service (MCS)
Meghalaya Civil Service (MCS)
Nagaland Civil Service (NCS)
Odisha Administrative Service (OAS)
Provincial Civil Service (Uttar Pradesh)
Punjab Civil Service (PCS)
Rajasthan Administrative Service (RAS)
Sikkim Civil Service (SCS)
Telangana Civil Service-Executive Branch (TCS)
Tamil Nadu Civil Service (TNCS)
West Bengal Civil Service (WBCS)

text: All state police services above the rank of Deputy SP are group A service. The officers of following services are later promoted to IPS.

text:
Andhra Pradesh State Police Service (APPS)
Arunachal Pradesh Police Service (APPS)
Assam Police Service (APS)
Bihar Police Service (BPS)
Goa Police Service (GPS)
State Police Service (SPS)
State Police Service (SPS)
Gujarat Police Service (GPS)
Haryana Police Service (HPS)
Himachal Pradesh Police Service (HPPS)
Jharkhand Police Service (JPS)
Kashmir Police Service (KPS)
Karnataka State Police Service (KSPS)

Kerala Police Service (KPS)
Manipur Police Service (MPS)
Mizoram Police Service (MPS)
Meghalaya Police Service (MPS)
Nagaland Police Service (NPS)
Odisha Police Service (OPS)
Provincial Police Service (PPS)
Punjab Police Service (PPS)
Rajasthan Police Service (RPS)
Sikkim Police Service (SPS)
Telangana Police Service (TPS)
Tamil Nadu Police Service (TNPS)
West Bengal Police Service (WBPS)

text: All state judicial services above the rank of Judicial Magistrate are group A service. The officers of following services are later promoted as judges in High Courts.

text:
Higher Judicial Service (HJS)
Provincial Civil Service-Judicial Branch (PCS-J)

text: State Services (Group B)[edit]

text: The state civil services (Group B) deal with subjects such as land revenue, agriculture, forests, education etc. The officers are recruited by different States through the respective State Public Service Commissions, and appointed by the Governor of that state.

text:
Assistant Registrar Cooperative Societies
Block Development Officer
District Employment Officer
District Food and Supplies Controller/Officer
District Treasury Officer
District Welfare Officer
Excise and Taxation Officer
Tehsildar/Talukadar/Assistant Collector
Any other Class-I/Class-II service notified as per rules by the concerned State, i.e. officers, lecturers, assistants, associate professors, or principals of Government Degree Colleges, Class I

text: Concerns and Reforms[edit]

text:
“

The IAS is hamstrung by political interference, outdated personnel procedures, and a mixed record on policy implementation, and it is in need of urgent reform. The Indian government should reshape recruitment and promotion processes, improve performance-based assessment of individual officers, and adopt safeguards that promote accountability while protecting bureaucrats from political meddling.

”

— The Indian Administrative Service Meets Big Data, Carnegie Endowment for International Peace[23][24]

text: As of 2011, in a duration of past three years over 450 chargesheets have been filed and a total of 943 cases are at different stages of investigation by CBI against civil servants.[25][26]

text:
“

We estimate that if India were to pursue civil service reforms and reach the Asian average on government effectiveness, it could add 0.9 percentage points annually to per capita GDP... Institutional quality is a crucial driver of economic performance.

”

—  Goldman Sachs report[27]

text: A study by the Hong Kong-based Political and Economic Risk Consultancy, released in 2012, ranked and rated Indian bureaucracy as the worst in Asia with a 9.21 rating out of 10. According to the study, India's inefficient and corrupt bureaucracy was responsible for most of the complaints that business executive have about the country.[28][29][30] A paper prepared in 2012 by the Ministry of Personnel, Public Grievances and Pensions states that corruption is prevalent at all levels in civil services and it is institutionalised.[31][32]

text: On 28 November 2011, the Department of Personnel and Training (DOPT) of the Ministry of Personnel, Public Grievances and Pensions created a proposal to retire and remove incompetent, inefficient and unproductive All India Service officers after 15 years of service, instead of tolerating them until their retirement. Former Cabinet Secretary TSR Subramanian welcomed this move with caution, saying, "Periodical weeding out is very good. But the process to determine who needs to be prematurely retired should be fair and transparent. There is a possibility that even good officers may be targeted because of political reasons,". Former UPSC chairman PC Hota echoed his sentiments remarking that, "We need drastic remedies. The situation has become terrible. The other day an officer in Delhi was arrested for disproportionate assets of Rs.31.5 million. She is just a 2000-batch IAS officer with 11 years of service. But at the same time, the officers' service records should be analysed before a decision against him was taken".[33][34][35] The proposal has been accepted and rule 16(3) of the All India Services (death-cum-retirement benefits) Rules of 1958 was amended on 31 January 2012.[33][35][36]

text: In October 2013, the Supreme Court of India, in the case of TSR Subramanian & Ors vs Union of India & Ors [37] ordered both Government of India and State governments to ensure fixed tenure to civil servants. The court asked senior bureaucrats to write down the oral instructions from politicians so that a record would be kept of all the decisions. This judgement was seen on the similar lines of the Supreme Court's 2006 judgement in Prakash Singh case on police reforms.[38][39] The judgement was welcomed by various bureaucrats and the media who hoped that it will help in giving freedom and independence to the functioning of bureaucracy.[40][41]

text:
"Much of the deterioration in the functioning of bureaucracy is due to political interference."

Justice K. S. Radhakrishnan and Justice P. C. Ghose, Supreme Court of India[40]

tag: div

text: In 2016, the Ministry of Finance for the first time, dismissed 72 and prematurely retired another 33 Indian Revenue Service officers for non-performance and on disciplinary grounds.[42][43][44][45][46] In 2016, it was reported that Government of India has decided to empower common man to seek prosecution of corrupt IAS officers.[47] Ministry of Personnel, Public Grievances and Pensions (DOPT) has accepted to receive requests from private persons seeking sanction for prosecution in respect of IAS officers without any proper proposal and supporting documents. [47]

text: Civil Services Day[edit]

text: The Civil Service Day is celebrated on 21 April every year.[48] The purpose for this day is to rededicate and recommit themselves to the cause of the people. It is observed by all Civil Services. This day gives civil servants the opportunity for introspection and thinking about future strategies to deal with the challenges being posed by the changing times.[49]

text: On this occasion, all officers of Central and State Governments are honoured for excellence in public administration by the Prime Minister of India. The 'Prime Minister Award for Excellence in Public Administration' is presented in three categories. Under this scheme of awards instituted in 2006, all the officers individually or as group or as organisation are eligible.[49]

text: The award includes a medal, scroll and a cash amount of ₹100,000 (US$1,500). In case of a group, the total award money is ₹500,000 (US$7,500) subject to a maximum of ₹100,000 (US$1,500) per person. For an organisation the cash amount is limited to ₹500,000 (US$7,500).[49]