10 Gas Exchange Transport.pptx - Anatomy Physiology Gas...

Anatomy & Physiology :
Gas Exchange:Transport
Dr. Heather Jones
[email protected]
866-8133

Diffusion of Gases
Gas exchange between alveoli and
blood
•
Oxygen diffuses into the blood
•
Carbon dioxide diffuses into the
alveoli
Diffusion across the alveolar membrane
•
Thickness
•
Surface area

Diffusion of Gases
Partial pressures: what are the gradients?

Diffusion of Gases
Henry’s law: at an air water interface, the amount
of gas which will dissolve is determined by the
partial pressure of the gases in the air and the
solubility in water
•
O
2
not very soluble in water
•
CO
2
more soluble in water
O
2
= 100 mm Hg * 0.03 mL O
2
/L/
mm Hg
O
2
= 0.3 mL O
2
/ 100 ml blood

Oxygen
Oxygen content in blood
•
Plasma alone vs. Plasma with
hemoglobin
•
P
O2
vs. O
2
Content
Hemoglobin
• Binds four O
2
molecules

Cooperative binding
•
Deoxyhemoglobin (Hb)
•
Oxyhemoglobin (HbO)

Oxygen
Oxygen transport:
1. Dissolved
2. Bound to Hb

Oxygen
Hemoglobin saturation =
O
2
bound to Hb
Maximal binding capacity of Hb to O
2
PO
2
determines binding affinity
•
High at lungs

Safety net in Hb situation