Gas Exchange

Question 1

What is gas exchange mediated by?

Answer 1

• thickness and surface of the respiratory membrane
• amount of gas available (partial pressures)
• the match between ventilation and perfusion (availability of gases and haemoglobin)

Question 2

What is flicks law?

Answer 2

The rate of diffusion of one material in another is proportional to the negative of the gradient of the concentration of the first material.

Question 3

What is Dalton’s law?

Answer 3

In a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

Question 4

How does oxygen travel through the blood stream?

Answer 4

1. Dissolved in plasma (blood gas)

2. Bound to haemoglobin

Question 5

What affects haemoglobins affinity for oxygen?

Answer 5

• temperature
• hydrogen concentration
• blood glucose level
• serum CO2 levels

Question 6

What happens when the dissociation curve shifts to the left?

Answer 6

At any given partial pressure of oxygen, the saturation will be higher. HB binds to oxygen more keenly but releases it at the tissue level less readily.

Question 7

What happens when the dissociation curve shifts to the right?

Answer 7

The saturation will be lower HB doesn’t bind to oxygen as well, but will release it at the tissue level more readily.

Question 8

What happens when there is a high PO2 and PCO2 in the lungs?

Answer 8

HB happily will shed its load of CO2 and picks up O2

Question 9

What is the Bohr effect?

Answer 9

The loss of affinity for oxygen with decreased PH as occurs in the micro circulation as oxygen is consumed and CO2 is released by tissues.

Question 10

What determines oxygenation at the tissues?

Answer 10

• 02 affinity Of HB
• 02 carrying capacity of the blood
• cardiac output
• distribution of blood flow