Movement Of 02& Co2

Question 1

Describe the factors that influence O2 movement into tissues

Answer 1

Heat
Partial pressures of gases
2,3 BPG
pH

Question 2

Describe co2 movement from tissues into blood and to lungs

Answer 2

The movement of O2 from RBC to tissues causes an increased affinity for Co2 (haldane effect)

5-10 binds to amino acids in HB

The rest combines with h20 and forms carbonic acid in plasma and then releases hydrogens and forms bicarbonate. (HH equation)

Transported to the lungs where the difference in partial pressure plus its solubility causes it to be expelled (Henry’s law)

Question 3

Describe 4 pathologies that affect influence the exchange of gases

Answer 3

Pneumonia: healthy respiratory membrane is very thin 0.5mm. Inflammatory exudate causes membrane thickening and fibrosis. This thickness reduces ease of gas exchange (ficks). RBC spend very little time in respiratory circulation, this leads to hypoxia.

Emphysema: the destruction of the airways when bullae are formed reduces the SA for gas exchange (ficks) leading to hypoxia

Emphysema: reduced volume of air entering alveoli, due to hyperinflation and fatigued diaphragm. This reduces the partial pressure gradient (ficks) and o2 is not very soluble (Henry’s)

PE: caused by atherosclerosis, if it ruptures and travels to pulmonary circulation. It will reduce the perfusion leading to a VQ mismatch and less gas exchange

Chronic bronchitis/ CF: the excess secretions will reduce the amount of air traveling to into the alevoli + reduce SA + thicken membrane

Question 4

Describe the movement of O2 from alveoli into the blood

Answer 4

Arrives at respiratory membrane
It diffuses rapidly into capillaries due to ficks law
Partial pressure is 104 compared to 40 in venous blood
The SA for gas exchange is enormous 300 million alveoli
The membrane is very thin 0.5 micrometers