1. Transport of gases in body Respiration (Breathing)

2. 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
Cellular respiration means intake of oxygen by cells from blood and releasing carbon dioxide into blood

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

4. Gas exchange between air and blood
Alveoli
Diameter appr. 0.3 mm
More than 300 milj. (→ m2)
Most dense network of capillaries in body
Gases are transported through 0.3 mm thick membranes
Capillary diameter 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:
(partial pressure =
concentration-% x air pressure)
Alveolar air:
(air is saturated with water in respiratory tract)

6. Exchange of gases air  blood  tissues
P = partial pressure
- Gases always move from higher partial pressures to lower through alveolar and capillary walls
- Blood stays only secs, enough time for exchange.

7. Transport of oxygen in body:
99% of blood oxygen in Hb and the rest dissolved in plasma and red cell fluids
1 g of red cell Hb binds 1.34 ml oxygen
Oxygen saturation of arterial blood in systemic circulation is appr. 97 %.
Venous blood appr. 75 % (at rest)
Oxygen saturation depends on partial pressure of oxygen in plasma (oxyhemoglobin dissociation curve)

8. HB4 + 4O2  Hb4O8 (works both ways)

9. Transport of carbon dioxide in body:
- Mostly bound in water (≤ 80%)
CO2 + H2O  H2CO3
one part (≤ 20%) bound in Hb (different site from oxygen)
small part dissolved (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) regulates ventilation so that partial pressures of O2 and CO2 in alveoli and arterial/venous blood stay roughly unchanged

12. Neural regulation (information from receptors in muscles,joints and lungs):
More important in ventilatory regulation than humoral factors
Powerful during exercise
Both voluntary and autonomous
Humoral regulation (information from chemoreceptors):
PCO2, PO2 and hydrogen ions (H+)
Most important regulatory mechanism at rest