document_title: Water distribution on Earth

question_text: what is the percentage of salt water in the world

root

text: Water distribution on Earth

text: Distribution of saline and fresh water[edit]

text: The total volume of water on Earth is estimated at 1.386 billion km³ (333 million cubic miles), with 97.5% being salt water and 2.5% being fresh water. Of the fresh water, only 0.3% is in liquid form on the surface.[7][8][9] In addition, the lower mantle of inner earth may hold as much as 5 times more water than all surface water combined (all oceans, all lakes, all rivers).[10]

tag: p

text:
Source of water
Volume of water
in km³ (cu mi)
% total
water
% salt
water
% fresh
water
% liquid surface
fresh water

Oceans
7018133800000000000♠1,338,000,000 (321,000,000)
96.5
99.0

Pacific Ocean
7017669880000000000♠669,880,000 (160,710,000)
48.3
49.6

Atlantic Ocean
7017310410900000000♠310,410,900 (74,471,500)
22.4
23.0

Indian Ocean
7017264000000000000♠264,000,000 (63,000,000)
19.0
19.5

Southern Ocean
7016718000000000000♠71,800,000 (17,200,000)
5.18
5.31

Arctic Ocean
7016187500000000000♠18,750,000 (4,500,000)
1.35
1.39

Ice and snow
7016243640000000000♠24,364,000 (5,845,000)
1.76

69.6

Glaciers
7016240640000000000♠24,064,000 (5,773,000)
1.74

68.7

Antarctic ice sheet
7016216000000000000♠21,600,000 (5,200,000)
1.56

61.7

Greenland ice sheet
7015234000000000000♠2,340,000 (560,000)
0.17

6.68

Arctic islands
7013835000000000000♠83,500 (20,000)
0.006

0.24

Mountain ranges
7013406000000000000♠40,600 (9,700)
0.003

0.12

Ground ice and permafrost
7014300000000000000♠300,000 (72,000)
0.022

0.86

Groundwater
7016234000000000000♠23,400,000 (5,600,000)
1.69

Saline groundwater
7016128700000000000♠12,870,000 (3,090,000)
0.93
0.95

Fresh groundwater
7016105300000000000♠10,530,000 (2,530,000)
0.76

30.1

Soil moisture
7013165000000000000♠16,500 (4,000)
0.0012

0.047

Lakes
7014176400000000000♠176,400 (42,300)
0.013

Saline lakes
7013854000000000000♠85,400 (20,500)
0.0062
0.0063

Caspian Sea
7013782000000000000♠78,200 (18,800)
0.0056
0.0058

Other saline lakes
7012720000000000000♠7,200 (1,700)
0.00052
0.00053

Fresh water lakes
7013910000000000000♠91,000 (22,000)
0.0066

0.26
87.0

African Great Lakes
7013300700000000000♠30,070 (7,210)
0.0022

0.086
28.8

Lake Baikal
7013236150000000000♠23,615 (5,666)
0.0017

0.067
22.6

North American Great Lakes
7013221150000000000♠22,115 (5,306)
0.0016

0.063
21.1

Other fresh water lakes
7013152000000000000♠15,200 (3,600)
0.0011

0.043
14.5

Atmosphere
7013129000000000000♠12,900 (3,100)
0.00093

0.037

Swamps
7013114700000000000♠11,470 (2,750)
0.00083

0.033
11.0

Rivers
7012212000000000000♠2,120 (510)
0.00015

0.0061
2.03

Biological water
7012112000000000000♠1,120 (270)
0.000081

0.0032

tag: table

text: Distribution of river water[edit]

text: The total volume of water in rivers is estimated at 2,120 km³ (510 cubic miles), or 2% of the surface fresh water on Earth.[7] Rivers and basins are often compared not according to their static volume, but to their flow of water, or surface runoff. The distribution of river runoff across the Earth's surface is very uneven.

text:
Continent or region
River runoff (km³/year)
Percent of world total

North America
7,800
17.9

South America
12,000
27.6

Europe
2,900
6.7

Middle East and North Africa
140
0.3

Sub-Saharan Africa
4,000
9.2

Asia (excluding Middle East)
13,300
30.6

Australia
440
1.0

Oceania
6,500
14.9

text: There can be huge variations within these regions. For example, as much as a quarter of Australia's limited renewable fresh water supply is found in almost uninhabited Cape York Peninsula.[11] Also, even in well-watered continents, there are areas that are extremely short of water, such as Texas in North America, whose renewable water supply totals only 26 km³/year in an area of 695,622 km², or South Africa, with only 44 km³/year in 1,221,037 km².[11] The areas of greatest concentration of renewable water are:

text:
The Amazon and Orinoco Basins (a total of 6,500 km³/year or 15 percent of global runoff)
East Asia

Yangtze Basin - 1,000 km³/year

South and Southeast Asia, with a total of 8,000 km³/year or 18 percent of global runoff

Brahmaputra Basin - 900 km³/year
Irrawaddy Basin - 500 km³/year
Mekong Basin - 450 km³/year

Canada, with over 10 percent of world's river water and large numbers in lakes

Mackenzie River - over 250 km³/year
Yukon River - over 150 km³/year

Siberia

Yenisey - over 5% of world's fresh water in basin - second largest after the Amazon
Ob River - over 500 km³/year
Lena River - over 450 km³/year

New Guinea

Fly and Sepik Rivers - total over 300 km³/year in only about 150,000 km² of basin area.

tag: ul

text: Area, volume, and depth of the world ocean[edit]

text:
Body of Water
Area (106 km2)
Volume (106 km3)
Mean Depth (m)

Atlantic Ocean
82.4
323.6
3,926

Pacific Ocean
165.2
707.6
4,282

Indian Ocean
73.4
291.0
3,963

All oceans and seas
361
1,370
3,796

text: Variability of water availability[edit]

text: Variability of water availability is important both for the functioning of aquatic species and also for the availability of water for human use: water that is only available in a few wet years must not be considered renewable. Because most global runoff comes from areas of very low climatic variability, the total global runoff is generally of low variability.

text: Indeed, even in most arid zones, there tends to be few problems with variability of runoff because most usable sources of water come from high mountain regions which provide highly reliable glacier melt as the chief source of water, which also comes in the summer peak period of high demand for water. This historically aided the development of many of the great civilizations of ancient history, and even today allows for agriculture in such productive areas as the San Joaquin Valley.

text: However, in Australia and Southern Africa, the story is different. Here, runoff variability is much higher than in other continental regions of the world with similar climates.[12] Typically temperate (Köppen climate classification C) and arid (Köppen climate classification B) climate rivers in Australia and Southern Africa have as much as three times the coefficient of variation of runoff of those in other continental regions.[13] The reason for this is that, whereas all other continents have had their soils largely shaped by Quaternary glaciation and mountain building, soils of Australia and Southern Africa have been largely unaltered since at least the early Cretaceous and generally since the previous ice age in the Carboniferous. Consequently, available nutrient levels in Australian and Southern African soils tend to be orders of magnitude lower than those of similar climates in other continents, and native flora compensate for this through much higher rooting densities (e.g. proteoid roots) to absorb minimal phosphorus and other nutrients. Because these roots absorb so much water, runoff in typical Australian and Southern African rivers does not occur until about 300 mm (12 inches) or more of rainfall has occurred. In other continents, runoff will occur after quite light rainfall due to the low rooting densities.

text:
Climate type (Köppen[14])
Mean annual rainfall
Typical runoff ratio
for Australia and Southern Africa
Typical runoff ratio
for rest of the world

BWh
250 mm (10 inches)
1 percent (2.5 mm)
10 percent (25 mm)

BSh (on Mediterranean fringe)
350 mm (14 inches)
3 percent (12 mm)
20 percent (80 mm)

Csa
500 mm (20 inches)
5 percent (25 mm)
35 percent (175 mm)

Caf
900 mm (36 inches)
15 percent (150 mm)
45 percent (400 mm)

Cb
1100 mm (43 inches)
25 percent (275 mm)
70 percent (770 mm)

text: The consequence of this is that many rivers in Australia and Southern Africa (as compared to extremely few in other continents) are theoretically impossible to regulate because rates of evaporation from dams mean a storage sufficiently large to theoretically regulate the river to a given level would actually allow very little draft to be used. Examples of such rivers include those in the Lake Eyre Basin. Even for other Australian rivers, a storage three times as large is needed to provide a third the supply of a comparable climate in southeastern North America or southern China. It also affects aquatic life, favouring strongly those species able to reproduce rapidly after high floods so that some will survive the next drought.

text: Tropical (Köppen climate classification A) climate rivers in Australia and Southern Africa do not, in contrast, have markedly lower runoff ratios than those of similar climates in other regions of the world. Although soils in tropical Australia and southern Africa are even poorer than those of the arid and temperate parts of these continents, vegetation can use organic phosphorus or phosphate dissolved in rainwater as a source of the nutrient. In cooler and drier climates these two related sources tend to be virtually useless, which is why such specialised means are needed to extract the most minimal phosphorus.

text: There are other isolated areas of high runoff variability, though these are basically due to erratic rainfall rather than different hydrology. These include:[13]

text:
Southwest Asia
The Brazilian Nordeste
The Great Plains of the United States

text: Water in Earth's mantle[edit]

text: It is estimated an additional 1.5 to eleven times the amount of water in the oceans is contained in the Earth's interior,[15] and some scientists have hypothesized that the water in the mantle is part of a "whole-Earth water cycle".[16] The water in the mantle is dissolved in various minerals near the transition zone between Earth's upper and lower mantle. At temperatures of 1,100 °C (2,010 °F) and extreme pressures found deep underground, water breaks down into hydroxyls and oxygen.[17] The existence of water was experimentally predicted in 2002,[18] and direct evidence of the water was found in 2014 based on tests on a sample of ringwoodite.[19] Further evidence for large quantities of water in the mantle was found in observations of melting in the transition zone from the USArray project.[20] Liquid water is not present within the ringwoodite, rather the components of water (hydrogen and oxygen) are held within as hydroxide ions.[19]


document_title: Lung

question_text: where is the apex of the lung located

question_tokens: where is the apex of the lung located

text: Lung

text: Structure of the human lungs[edit]

text: Anatomy[edit]

text: The lungs are located in the chest on either side of the heart in the rib cage. They are conical in shape with a narrow rounded apex at the top, and a broad concave base that rests on the convex surface of the diaphragm.[1] The apex of the lung extends into the root of the neck, reaching shortly above the level of the sternal end of the first rib. The lungs stretch from close to the backbone in the rib cage to the front of the chest and downwards from the lower part of the trachea to the diaphragm.[1] The left lung shares space with the heart, and has an indentation in its border called the cardiac notch of the left lung to accommodate this.[2][3] The front and outer sides of the lungs face the ribs, which make light indentations on their surfaces. The medial surfaces of the lungs face towards the centre of the chest, and lie against the heart, great vessels, and the carina where the trachea divides into the two main bronchi.[3] The cardiac impression is an indentation formed on the surfaces of the lungs where they rest against the heart.

text: Both lungs have a central recession called the hilum at the root of the lung, where the blood vessels and airways pass into the lungs.[1] There are also bronchopulmonary lymph nodes on the hilum.[3]

text: The lungs are surrounded by the pulmonary pleurae. The pleurae are two serous membranes; the outer parietal pleura lines the inner wall of the rib cage and the inner visceral pleura directly lines the surface of the lungs. Between the pleurae is a potential space called the pleural cavity containing a thin layer of lubricating pleural fluid. Each lung is divided into lobes by the infoldings of the pleura as fissures. The fissures are double folds of pleura that section the lungs and help in their expansion.[4]

text:
Lobes and bronchopulmonary segments [5]

Right lung
Left lung

Upper

Apical
Anterior
Posterior

Middle

Medial
Lateral

Lower

Superior
Anterior
Posterior
Medial
Lateral

Upper

Anterior
Apicoposterior

Lower

Superior
Anterior
Posterior
Medial
Lateral

Lingula

Superior
Inferior

text: The main or primary bronchi enter the lungs at the hilum and initially branch into secondary bronchi also known as lobar bronchi that supply air to each lobe of the lung. The lobar bronchi branch into tertiary bronchi also known as segmental bronchi and these supply air to the further divisions of the lobes known as bronchopulmonary segments. Each bronchopulmonary segment has its own (segmental) bronchus and arterial supply.[6] Segments for the left and right lung are shown in the table.[5] The segmental anatomy is useful clinically for localising disease processes in the lungs.[5] A segment is a discrete unit that can be surgically removed without seriously affecting surrounding tissue.[7]

text: Right lung[edit]

text: The right lung has both more lobes and segments than the left. It is divided into three lobes, an upper, middle, and a lower, by two fissures, one oblique and one horizontal.[8] The upper, horizontal fissure, separates the upper from the middle lobe. It begins in the lower oblique fissure near the posterior border of the lung, and, running horizontally forward, cuts the anterior border on a level with the sternal end of the fourth costal cartilage; on the mediastinal surface it may be traced backward to the hilum.[1]

text: The lower, oblique fissure, separates the lower from the middle and upper lobes, and is closely aligned with the oblique fissure in the left lung.[1][4]

text: The mediastinal surface of the right lung is indented by a number of nearby structures. The heart sits in an impression called the cardiac impression. Above the hilum of the lung is an arched groove for the azygos vein, and above this is a wide groove for the superior vena cava and right brachiocephalic vein; behind this, and close to the top of the lung is a groove for the brachiocephalic artery. There is a groove for the esophagus behind the hilum and the pulmonary ligament, and near the lower part of the esophageal groove is a deeper groove for the inferior vena cava before it enters the heart.[3]

text: Left lung[edit]

text: The left lung is divided into two lobes, an upper and a lower, by the oblique fissure, which extends from the costal to the mediastinal surface of the lung both above and below the hilum.[1] The left lung, unlike the right, does not have a middle lobe, though it does have a homologous feature, a projection of the upper lobe termed the "lingula". Its name means "little tongue". The lingula on the left serves as an anatomic parallel to the right middle lobe, with both areas being predisposed to similar infections and anatomic complications.[9][10] There are two bronchopulmonary segments of the lingula: superior and inferior.[1]

text: The mediastinal surface of the left lung has a large cardiac impression where the heart sits. This is deeper and larger than that on the right lung, at which level the heart projects to the left.[3]

text: On the same surface, immediately above the hilum, is a well-marked curved groove for the aortic arch, and a groove below it for the descending aorta. The left subclavian artery, a branch off the aortic arch, sits in a groove from the arch to near the apex of the lung. A shallower groove in front of the artery and near the edge of the lung, lodges the left brachiocephalic vein. The esophagus may sit in a wider shallow impression at the base of the lung.[3]

text: Microanatomy[edit]

text: The lungs are part of the lower respiratory tract, and accommodate the bronchial airways when they branch from the trachea. The lungs include the bronchial airways that terminate in alveoli, the lung tissue in between, and veins, arteries, nerves and lymphatic vessels.[3][11] The trachea and bronchi have plexuses of lymph capillaries in their mucosa and submucosa. The smaller bronchi have a single layer and they are absent in the alveoli.[12]

text: All of the lower respiratory tract including the trachea, bronchi, and bronchioles is lined with respiratory epithelium. This is a ciliated epithelium interspersed with goblet cells which produce mucus, and club cells with actions similar to macrophages. Incomplete rings of cartilage in the trachea and smaller plates of cartilage in the bronchi, keep these airways open.[13] Bronchioles are too narrow to support cartilage and their walls are of smooth muscle, and this is largely absent in the narrower respiratory bronchioles which are mainly just of epithelium.[13] The respiratory tract ends in lobules. Each lobule consists of a respiratory bronchiole, which branches into alveolar ducts and alveolar sacs, which in turn divide into alveoli.[3]

text: The epithelial cells throughout the respiratory tract secrete epithelial lining fluid (ELF), the composition of which is tightly regulated and determines how well mucociliary clearance works.[14][15]:Section 4 pages 7–8 (Page 4–7ff)

text: Alveoli consist of two types of alveolar cell and an alveolar macrophage. The two types of cell are known as type I and type II alveolar cells[16] (also known as pneumocytes).[3] Types I and II make up the walls and alveolar septa. Type I cells provide 95% of the surface area of each alveoli and are flat ("squamous"), and Type II cells generally cluster in the corners of the alveoli and have a cuboidal shape.[17] Despite this, cells occur in a roughly equal ratio of 1:1 or 6:4.[16][17]

text: Type I are squamous epithelial cells that make up the alveolar wall structure. They have extremely thin walls that enable an easy gas exchange.[16] These type I cells also make up the alveolar septa which separate each alveolus. The septa consist of an epithelial lining and associated basement membranes.[17] Type I cells are not able to divide, and consequently rely on differentiation from Type II cells.[17]

text: Type II are larger and they line the alveoli and produce and secrete epithelial lining fluid, and lung surfactant.[16] Type II cells are able to divide and differentiate to Type 1 cells.[17]

text: The alveolar macrophages have an important immunological role. They remove substances which deposit in the alveoli including loose red blood cells that have been forced out from blood vesels.[17]

text: The lung is surrounded by a serous membrane of visceral pleura, which has an underlying layer of loose connective tissue attached to the substance of the lung.[18]

text: Respiratory tract[edit]

text: The lower respiratory tract is part of the respiratory system, and consists of the trachea and the structures below this including the lungs.[16] The trachea receives air from the pharynx and travels down to a place where it splits (the carina) into a right and left bronchus. These supply air to the right and left lungs, splitting progressively into the secondary and tertiary bronchi for the lobes of the lungs, and into smaller and smaller bronchioles until they become the respiratory bronchioles. These in turn supply air through alveolar ducts into the alveoli, where the exchange of gases take place.[16] Oxygen breathed in, diffuses through the walls of the alveoli into the enveloping capillaries and into the circulation,[19] and carbon dioxide diffuses from the blood into the lungs to be breathed out.

text: Estimates of the total surface area of lungs vary from 50 to 75 square metres (540 to 810 sq ft);[16][17] roughly the same area as one side of a tennis court.[17][20]

text: The bronchi in the conducting zone are reinforced with hyaline cartilage in order to hold open the airways. The bronchioles have no cartilage and are surrounded instead by smooth muscle.[17] Air is warmed to 37 °C (99 °F), humidified and cleansed by the conducting zone; particles from the air being removed by the cilia on the respiratory epithelium lining the passageways.[21]

text: Pulmonary stretch receptors in the smooth muscle of the airways initiate a reflex known as the Hering–Breuer reflex that prevents the lungs from over-inflation, during forceful inspiration.

text: Blood supply[edit]

text: The lungs have a dual blood supply[16] provided by a bronchial and a pulmonary circulation. The bronchial circulation supplies oxygenated blood to the airways of the lungs, through the bronchial arteries that leave the aorta. There are usually three arteries, two to the left lung and one to the right, and they branch alongside the bronchi and bronchioles.[16] The pulmonary circulation carries deoxygenated blood from the heart to the lungs and returns the oxygenated blood to the heart to supply the rest of the body.[16]

text: The blood volume of the lungs, is about 450 millilitres on average, about 9 per cent of the total blood volume of the entire circulatory system. This quantity can easily fluctuate from between one-half and twice the normal volume.[22]

text: Nerve supply[edit]

text: The lungs are supplied by nerves of the autonomic nervous system. Input from the parasympathetic nervous system occurs via the vagus nerve. When stimulated by acetylcholine, this causes constriction of the smooth muscle lining the bronchus and bronchioles, and increases the secretions from glands.[23][page needed] The lungs also have a sympathetic tone from norepinephrine acting on the beta 2 receptors in the respiratory tract, which causes bronchodilation.[23][page needed]

text: The action of breathing takes place because of nerve signals sent by the respiratory centres in the brainstem, along the phrenic nerve to the diaphragm.[24][page needed]

text: Development[edit]

text: The development of the human lungs arise from the laryngotracheal groove and develop to maturity over several weeks in the foetus and for several years following birth.[25]

text: The larynx, trachea, bronchi and lungs that make up the respiratory tract, begin to form during the fourth week of embryogenesis[26] from the lung bud which appears ventrally to the caudal portion of the foregut.[27]

text: The respiratory tract has a branching structure like that of a tree.[28] In the embryo this structure is developed in the process of branching morphogenesis, and is generated by the repeated splitting of the tip of the branch. In the development of the lungs (as in some other organs) the epithelium forms branching tubes.The lung has a left-right symmetry and each bud known as a bronchial bud grows out as a tubular epithelium that becomes a bronchus. Each bronchus branches into bronchioles.[29] The branching is a result of the tip of each tube bifurcating.[28] The branching process forms the bronchi, bronchioles, and ultimately the alveoli.[28] The four genes mostly associated with branching morphogenesis in the lung are the intercellular signalling protein – sonic hedgehog (SHH), fibroblast growth factors FGF10 and FGFR2b, and bone morphogenetic protein BMP4. FGF10 is seen to have the most prominent role. FGF10 is a paracrine signalling molecule needed for epithelial branching, and SHH inhibits FGF10.[28][29] The development of the alveoli is influenced by a different mechanism whereby continued bifurcation is stopped and the distal tips become dilated to form the alveoli.

text: At the end of the fourth week the lung bud divides into two, the right and left primary bronchial buds on each side of the trachea.[30][31] During the fifth week the right bud branches into three secondary bronchial buds and the left branches into two secondary bronchial buds. These give rise to the lobes of the lungs, three on the right and two on the left. Over the following week, the secondary buds branch into tertiary buds, about ten on each side.[31] From the sixth week to the sixteenth week, the major elements of the lungs appear except the alveoli.[32] From week 16 to week 26, the bronchi enlarge and lung tissue becomes highly vascularised. Bronchioles and alveolar ducts also develop. By week 26 the terminal bronchioles have formed which branch into two respiratory bronchioles.[33] During the period covering the 26th week until birth the important blood–air barrier is established. Specialised type I alveolar cells where gas exchange will take place, together with the type II alveolar cells that secrete pulmonary surfactant, appear. The surfactant reduces the surface tension at the air-alveolar surface which allows expansion of the alveolar sacs. The alveolar sacs contain the primitive alveoli that form at the end of the alveolar ducts,[34] and their appearance around the seventh month marks the point at which limited respiration would be possible, and the premature baby could survive.[25]

text: After birth[edit]

text: At birth, the baby's lungs are filled with fluid secreted by the lungs and are not inflated. After birth the infant's central nervous system reacts to the sudden change in temperature and environment. This triggers the first breath, within about 10 seconds after delivery.[35] Before birth, the lungs are filled with fetal lung fluid.[36] After the first breath, the fluid is quickly absorbed into the body or exhaled. The resistance in the lung's blood vessels decreases giving an increased surface area for gas exchange, and the lungs begin to breathe spontaneously. This accompanies other changes which result in an increased amount of blood entering the lung tissues.[35]

text: At birth the lungs are very undeveloped with only around one sixth of the alveoli of the adult lung present.[25] The alveoli continue to form into early adulthood, and their ability to form when necessary is seen in the regeneration of the lung.[37][38] Alveolar septa have a double capillary network instead of the single network of the developed lung. Only after the maturation of the capillary network can the lung enter a normal phase of growth. Following the early growth in numbers of alveoli there is another stage of the alveoli being enlarged.[39]

text: Function[edit]

text: Gas exchange[edit]

text: The major function of the lungs is gas exchange between the lungs and the blood.[40] The alveolar and pulmonary capillary gases equilibrate across the thin blood–air barrier.[41][42] This thin membrane (about 0.5 –2 μm thick) is folded into about 300 million alveoli, providing an extremely large surface area (estimates varying between 70 and 145 m2) for gas exchange to occur.[41][43]

text: The lungs are not capable of expanding to breathe on their own, and will only do so when there is an increase in the volume of the thoracic cavity.[44] This is achieved by the muscles of respiration, through the contraction of the diaphragm, and the intercostal muscles which pull the rib cage upwards as shown in the diagram.[45] During breathing out the muscles relax, returning the lungs to their resting position.[46] At this point the lungs contain the functional residual capacity (FRC) of air, which, in the adult human, has a volume of about 2.5–3.0 litres.[46]

text: During heavy breathing as in exertion, a large number of accessory muscles in the neck and abdomen are recruited, that during exhalation pull the ribcage down, decreasing the volume of the thoracic cavity.[46] The FRC is now decreased, but since the lungs cannot be emptied completely there is still about a litre of residual air left.[46] Lung function testing is carried out to evaluate lung volumes and capacities.

text: Protection[edit]

text: The lungs possess several characteristics which protect against infection. The respiratory tract is lined by epithelia with hair-like projections called cilia that beat rhythmically and carry mucus. This mucociliary clearance is an important defence system against air-borne infection. The dust particles and bacteria in the inhaled air are caught in the mucosal surface of the airways, and are moved up towards the pharynx by the rhythmic upward beating action of the cilia.[17][47][48] The lining of the lung also secretes immunoglobulin A which protects against respiratory infections;[47] goblet cells secrete mucus[17] which also contains several antimicrobial compounds such as defensins, antiproteases, and antioxidates.[47] In addition, the lining of the lung also contains macrophages, immune cells which engulf and destroy debris and microbes that enter the lung in a process known as phagocytosis; and dendritic cells which present antigens to activate components of the adaptive immune system such as T-cells and B-cells.[47]

text: The size of the respiratory tract and the flow of air also protect the lungs from larger particles. Smaller particles deposit in the mouth and behind the mouth in the oropharynx, and larger particles are trapped in nasal hair after inhalation.[47]

text: Other[edit]

text: In addition to their function in respiration, the lungs have a number of other functions. They are involved in maintaining homeostasis, helping in the regulation of blood pressure as part of the renin–angiotensin system. The inner lining of the blood vessels secretes angiotensin-converting enzyme (ACE) an enzyme that catalyses the conversion of angiotensin I to angiotensin II.[49] The lungs are involved in the blood's acid-base homeostasis by expelling carbon dioxide when breathing.[44][50]

text: The lungs also serve a protective role. Several blood-borne substances, such as a few types of prostaglandins, leukotrienes, serotonin and bradykinin, are excreted through the lungs.[49] Drugs and other substances can be absorbed, modified or excreted in the lungs.[44][51] The lungs filter out small blood clots from veins and prevent them from entering arteries and causing strokes.[50]

text: The lungs also play a pivotal role in speech by providing air and airflow for the creation of vocal sounds,[44][52] and other paralanguage communications such as sighs and gasps.

text: New research suggests a role of the lungs in the production of blood platelets.[53]

text: Gene and protein expression[edit]

text: About 20,000 protein coding genes are expressed in human cells and almost 75% of these genes are expressed in the normal lung.[54][55] A little less than 200 of these genes are more specifically expressed in the lung with less 20 genes being highly lung specific. The corresponding specific proteins are expressed within different cellular compartments such as pneumocytes in alveoli, and ciliated and mucus secreting goblet cells in the respiratory mucosa. The highest expression of lung specific proteins are different surfactant proteins, such as SFTPA1, SFTPB and SFTPC, and napsin, expressed in type II pneumocytes. Other proteins with elevated expression in the lung are the dynein protein DNAH5 in ciliated cells, and the secreted SCGB1A1 protein in mucus secreting goblet cells of the airway mucosa.[56]

text: Clinical significance[edit]

text: Lungs can be affected by a variety of diseases. Pulmonology is the medical speciality that deals with diseases involving the respiratory tract,[57] and cardiothoracic surgery is the surgical field that deals with surgery of the lungs.[58]

text: Inflammatory conditions of the lung tissue are pneumonia, of the respiratory tract are bronchitis and bronchiolitis, and of the pleurae surrounding the lungs pleurisy. Inflammation is usually caused by infections due to bacteria or viruses. When the lung tissue is inflamed due to other causes it is called pneumonitis. One major cause of bacterial pneumonia is tuberculosis.[47] Chronic infections often occur in those with immunodeficiency and can include a fungal infection by Aspergillus fumigatus that can lead to an aspergilloma forming in the lung.[47][59]

text: A pulmonary embolism is a blood clot that becomes lodged in the pulmonary arteries. The majority of emboli arise because of deep vein thrombosis in the legs. Pulmonary emboli may be investigated using a ventilation/perfusion scan, a CT scan of the arteries of the lung, or blood tests such as the D-dimer.[47] Pulmonary hypertension describes an increased pressure at the beginning of the pulmonary artery that has a large number of differing causes.[47] Other rarer conditions may also affect the blood supply of the lung, such as granulomatosis with polyangiitis, which causes inflammation of the small blood vessels of the lungs and kidneys.[47]

text: A lung contusion is a bruise caused by chest trauma. It results in hemorrhage of the alveoli causing a build-up of fluid which can impair breathing, and this can be either mild or severe. The function of the lungs can also be affected by compression from fluid in the pleural cavity pleural effusion, or other substances such as air (pneumothorax), blood (hemothorax), or rarer causes. These may be investigated using a chest X-ray or CT scan, and may require the insertion of a surgical drain until the underlying cause is identified and treated.[47]

text: Asthma, chronic bronchitis, bronchiectasis and chronic obstructive pulmonary disease (COPD) are all obstructive lung diseases characterised by airway obstruction. This limits the amount of air that is able to enter alveoli because of constriction of the bronchial tree, due to inflammation. Obstructive lung diseases are often identified because of symptoms and diagnosed with pulmonary function tests such as spirometry. Many obstructive lung diseases are managed by avoiding triggers (such as dust mites or smoking), with symptom control such as bronchodilators, and with suppression of inflammation (such as through corticosteroids) in severe cases. One common cause of COPD and emphysema is smoking, and common causes of bronchiectasis include severe infections and cystic fibrosis. The definitive cause of asthma is not yet known.[47]

text: Some types of chronic lung diseases are classified as restrictive lung disease, because of a restriction in the amount of lung tissue involved in respiration. These include pulmonary fibrosis which can occur when the lung is inflamed for a long period of time. Fibrosis in the lung replaces functioning lung tissue with fibrous connective tissue. This can be due to a large variety of occupational diseases such as Coalworker's pneumoconiosis, autoimmune diseases or more rarely to a reaction to medication.[47]

text: Lung cancer can either arise directly from lung tissue or as a result of metastasis from another part of the body. There are two main types of primary tumour described as either small-cell or non-small-cell lung carcinomas. The major risk factor for cancer is smoking. Once a cancer is identified it is staged using scans such as a CT scan and a sample of tissue (a biopsy) is taken. Cancers may be treated by surgically removing the tumour, radiotherapy, chemotherapy or combinations thereof, or with the aim of symptom control.[47]Lung cancer screening is being recommended in the United States for high-risk populations.[60]

text: Congenital disorders include cystic fibrosis, pulmonary hypoplasia (an incomplete development of the lungs)[61]congenital diaphragmatic hernia, and infant respiratory distress syndrome caused by a deficiency in lung surfactant. An azygos lobe is a congenital anatomical variation which though usually without effect can cause problems in thoracoscopic procedures.[62]

text: A pneumothorax (collapsed lung) is an abnormal collection of air in the pleural space that causes an uncoupling of the lung from the chest wall.[63] The lung cannot expand against the air pressure inside the pleural space. An easy to understand example is a traumatic pneumothorax, where air enters the pleural space from outside the body, as occurs with puncture to the chest wall. Similarly, a scuba diver ascending while holding their breath with their lungs fully inflated can cause air sacs (alveoli) to burst and leak high pressure air into the pleural space.

text: Lung function testing[edit]

text: Lung function testing is carried out by evaluating a person's capacity to inhale and exhale in different circumstances.[64] The volume of air inhaled and exhaled by a person at rest is the tidal volume (normally 500-750mL); the inspiratory reserve volume and expiratory reserve volume are the additional amounts a person is able to forcibly inhale and exhale respectively. The summed total of forced inspiration and expiration is a person's vital capacity. Not all air is expelled from the lungs even after a forced breath out; the remainder of the air is called the residual volume. Together these terms are referred to as lung volumes.[64]

text: Pulmonary plethysmographs are used to measure functional residual capacity.[65] Functional residual capacity cannot be measured by tests that rely on breathing out, as a person is only able to breathe a maximum of 80% of their total functional capacity.[66] The total lung capacity depends on the person's age, height, weight, and sex, and normally ranges between 4 and 6 litres.[64] Females tend to have a 20–25% lower capacity than males. Tall people tend to have a larger total lung capacity than shorter people. Smokers have a lower capacity than nonsmokers. Thinner persons tend to have a larger capacity. Lung capacity can be increased by physical training as much as 40% but the effect may be modified by exposure to air pollution.[66][67]

text: Other lung function tests include spirometry, measuring the amount (volume) and flow of air that can be inhaled and exhaled. The maximum volume of breath that can be exhaled is called the vital capacity. In particular, how much a person is able to exhale in one second (called forced expiratory volume (FEV1)) as a proportion of how much they are able to exhale in total (FEV). This ratio, the FEV1/FEV ratio, is important to distinguish whether a lung disease is restrictive or obstructive.[47][64] Another test is that of the lung's diffusing capacity – this is a measure of the transfer of gas from air to the blood in the lung capillaries.

text: Other animals[edit]

text: Birds[edit]

text: The lungs of birds are relatively small, but are connected to 8 or 9 air sacs that extend through much of the body, and are in turn connected to air spaces within the bones. On inhalation, air travels through the trachea of a bird into the air sacs. Air then travels continuously from the air sacs at the back, through the lungs, which are relatively fixed in size, to the air sacs at the front. From here, the air is exhaled. These fixed size lungs are called "circulatory lungs", as distinct from the "bellows-type lungs" found in most other animals.[68][70]

text: The lungs of birds contain millions of tiny parallel passages called parabronchi. Small sacs called atria radiate from the walls of the tiny passages; these, like the alveoli in other lungs, are the site of gas exchange by simple diffusion.[70] The blood flow around the parabronchi and their atria forms a cross-current process of gas exchange (see diagram on the right).[68][69]

text: The air sacs, which hold air, do not contribute much to gas exchange, despite being thin-walled, as they are poorly vascularised. The air sacs expand and contract due to changes in the volume in the thorax and abdomen. This volume change is caused by the movement of the sternum and ribs and this movement is often synchronised with movement of the flight muscles.[71]

text: Parabronchi in which the air flow is unidirectional are called paleopulmonic parabronchi and are found in all birds. Some birds, however, have, in addition, a lung structure where the air flow in the parabronchi is bidirectional. These are termed neopulmonic parabronchi.[70]

text: Reptiles[edit]

text: The lungs of most reptiles have a single bronchus running down the centre, from which numerous branches reach out to individual pockets throughout the lungs. These pockets are similar to alveoli in mammals, but much larger and fewer in number. These give the lung a sponge-like texture. In tuataras, snakes, and some lizards, the lungs are simpler in structure, similar to that of typical amphibians.[71]

text: Snakes and limbless lizards typically possess only the right lung as a major respiratory organ; the left lung is greatly reduced, or even absent. Amphisbaenians, however, have the opposite arrangement, with a major left lung, and a reduced or absent right lung.[71]

text: Both crocodilians and monitor lizards have developed lungs similar to those of birds, providing an unidirectional airflow and even possessing air sacs.[72] The now extinct pterosaurs have seemingly even further refined this type of lung, extending the airsacs into the wing membranes and, in the case of lonchodectids, tupuxuara, and azhdarchoids, the hindlimbs.[73]

text: Reptilian lungs typically receive air via expansion and contraction of the ribs driven by axial muscles and buccal pumping. Crocodilians also rely on the hepatic piston method, in which the liver is pulled back by a muscle anchored to the pubic bone (part of the pelvis) called the diaphragmaticus,[74] which in turn creates negative pressure in the crocodile's thoracic cavity, allowing air to be moved into the lungs by Boyle's law. Turtles, which are unable to move their ribs, instead use their forelimbs and pectoral girdle to force air in and out of the lungs.[71]

text: Amphibians[edit]

text: The lungs of most frogs and other amphibians are simple and balloon-like, with gas exchange limited to the outer surface of the lung. This is not very efficient, but amphibians have low metabolic demands and can also quickly dispose of carbon dioxide by diffusion across their skin in water, and supplement their oxygen supply by the same method. Amphibians employ a positive pressure system to get air to their lungs, forcing air down into the lungs by buccal pumping. This is distinct from most higher vertebrates, who use a breathing system driven by negative pressure where the lungs are inflated by expanding the rib cage.[75] In buccal pumping, the floor of the mouth is lowered, filling the mouth cavity with air. The throat muscles then presses the throat against the underside of the skull, forcing the air into the lungs.[76]

text: Due to the possibility of respiration across the skin combined with small size, all known lungless tetrapods are amphibians. The majority of salamander species are lungless salamanders, which respirate through their skin and tissues lining their mouth. This necessarily restrict their size: all are small and rather thread-like in appearance, maximising skin surface relative to body volume.[77] Other known lungless tetrapods are the Bornean flat-headed frog[78] and Atretochoana eiselti, a caecilian.[79]

text: The lungs of amphibians typically have a few narrow internal walls (septa) of soft tissue around the outer walls, increasing the respiratory surface area and giving the lung a honey-comb appearance. In some salamanders even these are lacking, and the lung has a smooth wall. In caecilians, as in snakes, only the right lung attains any size or development.[71]

text: Lungfish[edit]

text: The lungs of lungfish are similar to those of amphibians, with few, if any, internal septa. In the Australian lungfish, there is only a single lung, albeit divided into two lobes. Other lungfish and Polypterus, however, have two lungs, which are located in the upper part of the body, with the connecting duct curving around and above the esophagus. The blood supply also twists around the esophagus, suggesting that the lungs originally evolved in the ventral part of the body, as in other vertebrates.[71]

text: Invertebrates[edit]

text: Some invertebrates have lung-like structures that serve a similar respiratory purpose as, but are not evolutionarily related to, vertebrate lungs. Some arachnids, such as spiders and scorpions, have structures called book lungs used for atmospheric gas exchange. Some species of spider have four pairs of book lungs but most have two pairs.[80] Scorpions have spiracles on their body for the entrance of air to the book lungs.[81]

text: The coconut crab is terrestrial and uses structures called branchiostegal lungs to breathe air.[82] They cannot swim and would drown in water, yet they possess a rudimentary set of gills. They can breathe on land and hold their breath underwater.[83] The branchiostegal lungs are seen as a developmental adaptive stage from water-living to enable land-living, or from fish to amphibian.[84]

text: Pulmonates are mostly land snails and slugs that have developed a simple lung from the mantle cavity. An externally located opening called the pneumostome allows air to be taken into the mantle cavity lung.[85][86]

text: Evolutionary origins[edit]

text: The lungs of today's terrestrial vertebrates and the gas bladders of today's fish are believed to have evolved from simple sacs, as outpocketings of the esophagus, that allowed early fish to gulp air under oxygen-poor conditions.[87] These outpocketings first arose in the bony fish. In most of the ray-finned fish the sacs evolved into closed off gas bladders, while a number of carp, trout, herring, catfish, and eels have retained the physostome condition with the sack being open to the esophagus. In more basal bony fish, such as the gar, bichir, bowfin and the lobe-finned fish, the bladders have evolved to primarily function as lungs.[87] The lobe-finned fish gave rise to the land-based tetrapods. Thus, the lungs of vertebrates are homologous to the gas bladders of fish (but not to their gills).[88]


document_title: United States congressional conference committee

question_text: where does a bill go next if the conference committee succeeds

text: Going to conference[edit]

text: Conference committees operate after the House and the Senate have passed different versions of a bill. Conference committees exist to draft a compromise bill that both houses can accept. Both houses of Congress must eventually pass identical legislation for the bill to be presented to the President. [1] The two houses can reach that point through the process of amendments between Houses, where the House passes the Senate bill with a House amendment, or vice versa, but this process can be cumbersome. Thus, some bills pass both Houses through the use of a conference committee. [2]

text: After one house passes a bill, the second house often passes the same bill, with an amendment representing the second house's work product. The second house then sends a message to the first house, asking the first house to concur with the second house's amendment. If the first house does not like the second house's amendment, then the first house can disagree with the amendment of the second house, request a conference, appoint conferees, and send a message to that effect to the second house. The second house then insists on its amendment, agrees to a conference, and appoints conferees.

text: Each house determines the number of conferees from its house. The number of conferees need not be equal. To conclude its business, a majority of both House and Senate delegations to the conference must indicate their approval by signing the conference report.

text: The authority to appoint conferees lies in the entire House, and the entire Senate can appoint conferees by adopting a debatable motion to do so.[3] But leadership have increasingly exercised authority in the appointment of conferees.

text: The House and Senate may instruct conferees, but these instructions are not binding.[4]

text: Authority[edit]

text: Conference committees can be extremely contentious, particularly if the houses are controlled by different parties. House rules require that one conference meeting be open to the public, unless the House, in open session, votes to close a meeting to the public. Apart from this one open meeting, conference committees usually meet in private, and are dominated by the chairs of the House and Senate committees.[citation needed]

text: House and Senate rules forbid conferees from inserting in their report matter not committed to them by either House. [5][6] But conference committees sometimes do introduce new matter. In such a case, the rules of each House let a member object through a point of order, though each House has procedures that let other members vote to waive the point of order. The House provides a procedure for striking the offending provision from the bill. Formerly, the Senate required a Senator to object to the whole bill as reported by the conference committee. If the objection was well-founded, the Presiding Officer ruled, and a Senator could appeal the ruling of the Chair. If the appeal was sustained by a majority of the Senate, it had precedential effect, eroding the rule on the scope of conference committees. From fall 1996 through 2000, the Senate had no limit on the scope of conference reports, and some argued that the majority abused the power of conference committees. [7] In December 2000, the Senate reinstated the prohibition of inserting matters outside the scope of conference. [8] The rule changed again with the Honest Leadership and Open Government Act, enacted in September 2007. Now any single Senator may raise a point of order against subject matter newly inserted by the conference committee without objecting to the rest of the bill. Proponents of the measure may move to waive the rule. The affirmative vote of 60 Senators is required to waive the rule. If the point of order is not waived and the Chair rules that the objection is well-founded, only the offending provision is stricken from the measure, and the Senate votes on sending the balance of the measure back to the House.[6]

text: Conference report[edit]

text: Most times, the conference committee produces a conference report melding the work of the House and Senate into a final version of the bill. A conference report proposes legislative language as an amendment to the bill committed to conference. The conference report also includes a joint explanatory statement of the conference committee. This statement provides one of the best sources of legislative history on the bill. Chief Justice William Rehnquist once observed that the joint conference report of both Houses of Congress is considered highly reliable legislative history when interpreting a statute.[9]

text: Once a bill has been passed by a conference committee, it goes directly to the floor of both houses for a vote, and is not open to further amendment. In the first house to consider the conference report, a Member may move to recommit the bill to the conference committee. But once the first house has passed the conference report, the conference committee is dissolved, and the second house to act can no longer recommit the bill to conference.[10]

text: Conference reports are privileged. In the Senate, a motion to proceed to a conference report is not debatable, although Senators can generally filibuster the conference report itself. The Congressional Budget Act of 1974 limits debate on conference reports on budget resolutions and budget reconciliation bills to ten hours in the Senate, so Senators cannot filibuster those conference reports.[11]

text: The conference report must be approved by both the House and the Senate before the final bill is sent to the President.[10]

text: Declining usage[edit]

text: The use of the formal conference process has steadily declined in recent decades.  The number of conference reports produced is shown below from the 104th Congress (1995-96) through the 115th Congress (2017-18) as of 12/14/2017:[12]


document_title: European exploration of Australia

question_text: where did the first european land in australia

text: European exploration of Australia

text: The European exploration of Australia began at least as early as 1605–1606, when seafarers first explored and mapped the Australian coastline. The first documented encounter was that of Dutch navigator Willem Janszoon, in 1606. Dutch seafarers also visited the west and north coasts of the continent, as did French explorers. The most famous expedition was that of Royal Navy Lieutenant (later Captain) James Cook 164 years after Janszoon's sighting, who after an assignment to make observations of the 1769 Venus Transit, followed Admiralty instructions to explore the south Pacific for the reported Terra Australis and on 19 April 1770 sighted the south-eastern coast of Australia and became the first recorded European to explore the eastern coastline. Explorers by land and sea continued to survey the continent for some years after settlement. These efforts consisted of:

text:
European maritime exploration of Australia, and
European land exploration of Australia

text: This article includes a list of related items that share the same name (or similar names).  If an internal link incorrectly led you here, you may wish to change the link to point directly to the intended article.

text: Set indices1605 establishments in AustraliaExploration of Australia

text: Use dmy dates from April 2018Use Australian English from April 2018All Wikipedia articles written in Australian EnglishAll set index articles


document_title: List of towns and cities with 100,000 or more inhabitants/cityname: F

question_text: cities that start with f in the us

question_tokens: cities that start with f in the us

text: List of cities beginning with letter F[edit]

text:
City
Country

Faisalabad
 Pakistan

Faizabad
 India

Faridabad
 India

Farrukhabad
 India

Fatehpur
 India

Fayetteville
 United States

Fayyum
 Egypt

Feira de Santana
 Brazil

Fengcheng
 China

Fenghua
 China

Fergana
 Uzbekistan

Ferrara
 Italy

Ferraz de Vasconcelos
 Brazil

Fes
 Morocco

Firozabad
 India

Flint
 United States

Florence
 Italy

Florencia
 Colombia

Florianópolis
 Brazil

Floridablanca
 Colombia

Focşani
 Romania

Foggia
 Italy

Fontana
 United States

Forlì
 Italy

Formosa
 Argentina

Fort Collins
 United States

Fort Lauderdale
 United States

Fort Wayne
 United States

Fort Worth
 United States

Fortaleza
 Brazil

Fort-de-France
 Martinique

Foshan
 China

Foz do Iguaçu
 Brazil

Franca
 Brazil

Francisco Morato
 Brazil

Francistown
 Botswana

Franco da Rocha
 Brazil

Frankfurt am Main
 Germany

Freetown
 Sierra Leone

Freiburg im Breisgau
 Germany

Fremont
 United States

Fresno
 United States

Fu'an
 China

Fuchu
 Japan

Fuenlabrada
 Spain

Fuji
 Japan

Fujieda
 Japan

Fujimi
 Japan

Fujin City
 China

Fujinomiya
 Japan

Fujisawa
 Japan

Fukuya
 Japan

Fukui
 Japan

Fukuoka
 Japan

Fukushima
 Japan

Fukuyama
 Japan

Fuling
 China

Fullerton
 United States

Funabashi
 Japan

Funchal
 Portugal

Fushun
 China

Fuxin
 China

Fuyang
 China

Fuzhou, Fujian
 China

Fuzhou, Jiangxi
 China

Fürth
 Germany