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Transport of gases in body Respiration ( Breathing )

Transport of gases in body Respiration ( Breathing ). Respiration. = transport of oxygen from air into cells and carbon dioxide from cells to air Ventilation means inhaling air into alveoli and exhaling out of them Gas exchange between air blood  tissues

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Transport of gases in body Respiration ( Breathing )

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  1. Transport of gases in body Respiration (Breathing)

  2. Respiration = transport of oxygenfrom air into cells and carbondioxidefromcells to air • Ventilationmeansinhaling air into alveoli and exhaling out of them • Gasexchangebetweenairblood tissues • Cellularrespirationmeansintake of oxygenbycellsfromblood and releasingcarbondioxide into blood

  3. VENTILATION • Active inspiration by inspiration muscles,passive expiration by elasticity of rib cage • In intensive work also exhaling by muscles

  4. Gasexchangebetween air and blood Alveoli • Diameter appr. 0.3 mm • Morethan 300 milj. (→50-100 m2) • Mostdensenetwork of capillaries in body • Gasesaretransportedthrough 0.3 mm thickmembranes • Capillarydiameter appr. 8 mm, contain 100 ml of blood→ a cup of coffee on a tennis field !

  5. Exchange of gases air  blood tissues Atmospheric air: (partialpressure = concentration-% x air pressure) Alveolar air: (air is saturatedwithwater in respiratorytract)

  6. Exchange of gases air  blood tissues P = partial pressure - Gasesalwaysmovefromhigherpartialpressures to lowerthroughalveolar and capillarywalls - Bloodstaysonly 0.4 -0.8 secs, enoughtime for exchange.

  7. Transport of oxygen in body: • 99% of bloodoxygen in Hb and the restdissolved in plasma and redcellfluids • 1 g of redcellHbbinds 1.34 ml oxygen • Oxygensaturation of arterialblood in systemiccirculation is appr. 97 %. • Venousblood appr. 75 % (at rest) • Oxygensaturationdepends on partialpressure of oxygen in plasma (oxyhemoglobindissociationcurve)

  8. HB4 + 4O2  Hb4O8 (worksbothways)

  9. Transport of carbondioxide in body: • - Mostlybound in water (≤ 80%) • CO2 + H2O  H2CO3 • onepart (≤ 20%) bound in Hb (differentsitefromoxygen) • smallpartdissolved (5%)

  10. MB4 + O2  MbO2 (toimii molempiin suuntiin) • Myoglobin: • O2 storage in muscles and heart • protein with iron as Hb • binds one molecule of O2 • releases O2 only after PO2 decreases very low

  11. RESPIRATORY REGULATION • Respiratory center (in medulla)regulatesventilationsothatpartialpressures of O2 and CO2 in alveoli and arterial/venousbloodstayroughlyunchanged

  12. Neuralregulation(informationfromreceptors in muscles,joints and lungs): • Moreimportant in ventilatoryregulationthanhumoralfactors • Powerfulduringexercise • Bothvoluntary and autonomous Humoralregulation(informationfromchemoreceptors): • PCO2, PO2 and hydrogenions (H+) • Mostimportantregulatorymechanism at rest

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