transport of resp gases Reeshma

1. • Transport of
Respiratory gases
(O2 & CO2)

2. Contents
• Introduction
• Diffusion of gases
• Transport of Oxygen
• Transport of Carbon Dioxide
• Respiratory exchange Ratio

3. Diffusion of Respiratory Gases
• Respiratory Membrane
• Diffusion of O2 across respiratory membrane
• Diffusion of O2 from peripheral capillaries
into tissue fluid
• Diffusion of CO2 from tissue fluid into
peripheral capillaries
• Diffusion of CO2 across respiratory
membrane

4. Diffusion
• B/W alveoli &
Pul. Capillaries
• B/W Syst.
Capillaries &
Tissues

5. Factors Affecting Diffusion
1. Thickness of membrane
2. Surface area of membrane
3. Diffusion coefficient of gas in the
substance of membrane
4. Partial pressure difference

7. Respiratory Membrane

8. • Alveolar capillary obstruction syndrome
• Seen in( a) thickening of alveolar capillary
membrane , (b) increased distance b/w
alveolar & capillary membrane
• Here O2 diffusion decreased, but not CO2

9. Diffusing capacity of respiratory
membrane is defined as the volume
of gas that will diffuse through the
membrane each minute for a partial
pressure difference of 1 mmHg
O2 : 21ml/min/mmHg
CO2 : 400ml/min/mmHg

10. Uptake of O2 by pulmonary
capillary blood

11. Diffusion of O2 from tissue
capillary to cells

12. Diffusion of CO2 from tissue fluid
into peripheral capillaries

13. Diffusion of CO2 across
respiratory membrane

14. Ventilation Perfusion Ratio
• Ratio of alveolar ventilation to pulmonary
blood flow 4L/min/5L/min = 0.8
• Facors affecting V/P ratio :
• Effect of Gravity
• Bronchial asthma, pneumothorax,
emphysema , pulmonary fibrosis , Congestive
heart failure, anatomical shunts, emphysema,
pulmonary embolism

15. • High V/P ratio in apices predisposes , to TB,
because high alveolar pO2 provides favourable
environment for growth of TB bacteria

16. Transport of Oxygen
• 97 % : By combining with Hb
• 3% : In the dissolved state
• Amount transported: 5ml/100ml

17. Distribution of O2 in body
pO2 O2content
Inspired air 158 21ml/dl
Expired air 116 16ml/dl
Alveolar air 100-104 13-14ml/dl
Arterial blood 98-100 19ml
Venous blood 40 14ml

18. Oxygen – Hemoglobin dissociation
Curve

19. The relationship between PO2, oxygen
saturation, and oxygen content is by the
oxyhemoglobin equilibrium curve, an
S-shaped curve over a range of arterial
oxygen tensions, from 0 to 100 mm Hg.
The shape of the curve results because
the hemoglobin affinity for oxygen
increases, progressively as blood PO2
increases.

20. The maximum amount of oxygen that
can be carried by hemoglobin is called
the oxygen carrying capacity—about 20
mL O2/dL blood in a healthy young
adult.
• Oxygen content is the amount of oxygen
actually bound to hemoglobin (whereas
capacity is the amount that can
potentially be bound).

21. • Sigmoid shape
• P50
• Bohr effect
• Maximum amount of O2 that
can combine with Hb & O2
released to tissues
• Utilization coefficient

22. Factors that shift oxygen
Haemoglobin Dissociation curve
• H+ ions
• CO2
• Temperature
• BPG
• pH
• Exercise
• Myoglobin
• HbF

25. Transport of O2 in Dissolved state
• 0.29ml/100ml at 95mmHg (3%)
• Exercise :1.5%
• Oxygen poisoning

26. CO poisoning

27. Transport of Carbon Dioxide
• As bicarbonate ions : 70%
(3ml/dl)
• As carbaminocompounds : 23%
(0.7ml/dl)
• Dissolved state : 7% (0.3ml/dl)

28. As bicarbonate ions : 70% (3ml)

29. Carbaminocompounds : 23%
• Carbaminoprotein : 0.1ml/dl
• Carbaminohemoglobin : 0.6ml/dl

30. Dissolved state
• 0.3ml/100ml (7%)

31. Carbon Dioxide Dissociation Curve

32. Haldane Effect
• Binding of oxygen with Hb tend to displaces
CO2 from blood

33. Respiratory exchange Ratio
• R = Rate of CO2 output
rate of O2 uptake