Oxygen and CO2 transport I

Question 1

In what two forms is oxygen carried in the blood?

Answer 1

Bound to Hemoglobin

Dissolved in plasma - this is what contributes to the partial pressure of oxygen in blood

Question 2

Describe the equilibrium relationship between dissolved oxygen and bound oxygen.

Answer 2

Dissolved oxygen and bound oxygen are in equilibrium with each other

Increasing the PO2 increases the amount of oxygen dissolved in blood, and shifts the equilibrium towards bound oxygen

Decreasing the PO2 lowers the amount of dissolved oxygen and shifts the the equilibrium towards dissolved oxygen

Question 3

How is oxygen delivered from the blood to the tissue?

Answer 3

Oxygen moves down is partial pressure gradient from the vascular compartment to the tissues as dissolved gas

This lowers the partial pressure in plasma and causes more oxygen to dissociate from Hb

Question 4

How does Hb act as a buffer for oxygen?

Answer 4

For a fall of PO2 from 100 to 60mmHg the buffering effects of Hb makes sure that tissue PO2 only changes by 5mmHg

Question 5

What are the two mechanisms that CO poisoning can kill you?

Answer 5

Reduces transport by occupying O2 binding sites

Raises the affinity of the remaining O2 binding sites for O2. This means taht the unloading of O2 can only happen when PO2 is lowered to very low levels

Question 6

What is oxygen capacity?

Answer 6

Maximal amount of oxygen Hb is capable of carrying

Does not include dissolved oxygen

Hb saturation = O2 bound/capacity x 100

Question 7

What is respiratory acidosis?

Answer 7

Condition that occurs when the lungs cannot remove all of the carbon dioxide the body produces

Hypercapnia causes the blood to become too acidic

Question 8

What is respiratory alkalosis?

Answer 8

Condition that occurs when the carbon dioxide is removed too quickly from the lungs (due to hyperventilation)