All about respiratory system

1. Respiratory System - 3

4. O2 Transport
• 1 Hb can bind to 4 O2 molecules
• 1-3 O2 molecules bound to Hb – partially saturated Hb
• Hb binding depends on the partial pressure of the gases
• Co-operative binding of O2 to Hb – oxygenation of Hb and not oxidation
• Oxygen capacity – Max amt of O2 that combines chemically with Hb per unit volume of blood.
Arterial blood = 1.34 ml of O2 / gm of Hb = 19.5 ml of O2 /100 ml of blood
• Oxygen saturation – Measure of how much O2 blood is carrying as a % of the max carrying capacity

5. O2 dissociation curve
• Reveals amt of Hb saturation at different pO2
(x,y) = (10,10), (20,40), (40,75),
(60,90), (80, 95), (100, 98)

6. • At high pO2, the saturation is stable, ie, plateau.
• At low pO2, the saturation falls rapidly
• At tissue level, pO2 = 40, saturation of Hb = 75%
• At lung level, pO2 = 100, saturation of Hb = 98%
• So at rest, the saturation is still 75% - reserve for
exertion, ie, during exercise, pO2 at tissue level falls
less than 40 and so the O2 will dissociate more from
Hb
Decreased pCO2
increased pCO2

7. Hypoxia
• O2 deficiency at the tissue
level.

8. Types of Hypoxia Arterial pO2 Hb Levels Rate of blood flow to tissues
Hypoxic Hypoxia Decreases Normal Normal
Anemic Hypoxia Normal Decreases Normal
Stagnant Hypoxia Normal Normal Decreases
Histotoxic Hypoxia Normal Normal Normal