Blood–air barrier

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Blood–air barrier_table_infobox_0

Blood–air barrierBlood–air barrier_header_cell_0_0_0
DetailsBlood–air barrier_header_cell_0_1_0
SystemBlood–air barrier_header_cell_0_2_0 Respiratory systemBlood–air barrier_cell_0_2_1
LocationBlood–air barrier_header_cell_0_3_0 LungsBlood–air barrier_cell_0_3_1
IdentifiersBlood–air barrier_header_cell_0_4_0
MeSHBlood–air barrier_header_cell_0_5_0 Blood–air barrier_cell_0_5_1
THBlood–air barrier_header_cell_0_6_0 Blood–air barrier_cell_0_6_1

The blood–air barrier (alveolar–capillary barrier or membrane) exists in the gas exchanging region of the lungs. Blood–air barrier_sentence_0

It exists to prevent air bubbles from forming in the blood, and from blood entering the alveoli. Blood–air barrier_sentence_1

It is formed by the type 1 pneumocytes of the alveolar wall, the endothelial cells of the capillaries and the basement membrane between the two cells. Blood–air barrier_sentence_2

The barrier is permeable to molecular oxygen, carbon dioxide, carbon monoxide and many other gases. Blood–air barrier_sentence_3

Structure Blood–air barrier_section_0

This blood-air barrier is extremely thin (approximately 600 nm-2μm; in some places merely 200 nm) to allow sufficient oxygen diffusion, yet it is extremely strong. Blood–air barrier_sentence_4

This strength comes from the type IV collagen in between the endothelial and epithelial cells. Blood–air barrier_sentence_5

Damage can occur to this barrier at a pressure difference of around 40 millimetres of mercury (0.053 bar). Blood–air barrier_sentence_6

Clinical significance Blood–air barrier_section_1

Failure of the barrier may occur in a pulmonary barotrauma. Blood–air barrier_sentence_7

This can be a result of several possible causes, including blast injury, swimming-induced pulmonary edema, and breathing gas entrapment or retention in the lung during depressurization, which can occur during ascent from underwater diving or loss of pressure from a pressurized vehicle, habitat or pressure suit. Blood–air barrier_sentence_8

Possible consequences of rupture of the blood–air barrier include arterial gas embolism and hemoptysis. Blood–air barrier_sentence_9

See also Blood–air barrier_section_2

Blood–air barrier_unordered_list_0

  • Blood–brain barrier – Semipermeable capillary border that allows selective passage of blood constituents into the brainBlood–air barrier_item_0_0
  • Blood–ocular barrier – A physical barrier between the local blood vessels and most parts of the eye itselfBlood–air barrier_item_0_1
  • Blood–retinal barrier – Part of the blood–ocular barrier that prevents certain substances from entering the retinaBlood–air barrier_item_0_2
  • Blood–testis barrier – A physical barrier between the blood vessels and the seminiferous tubules of the animal testesBlood–air barrier_item_0_3
  • Blood–thymus barrier – A barrier formed by the continuous blood capillaries in the thymic cortexBlood–air barrier_item_0_4
  • Pulmonary vein – The veins that transfer oxygenated blood from the lungs to the heartBlood–air barrier_item_0_5

Credits to the contents of this page go to the authors of the corresponding Wikipedia page:–air barrier.