Gas exchange + Gas transport

Question 1

What law explains gas exchange?

Answer 1

Ficks Law.

Question 2

What factors influence the gas exchange rate?

Answer 2

• Tissue area.
• Diffusion coeffcient.
• Partial pressure difference.

Question 3

What does diffusion coefficient mean?

Answer 3

Determined by the gas solubility + molecular weight.

Question 4

What is CO2’s diffusion coeffcient?

Answer 4

20x higher than oxygen.

Question 5

What structural aspects optimise gas exchange in the lungs?

Answer 5

• Large surface area.
• Thin alveolar membrane.
• Dense capillary bed.

Question 6

Explain the benefit of a thin alveolar membrane in the lungs with regard to gas exchange.

Answer 6

There is a reduced distance for gases to diffuse into the lungs.

Question 7

Explain the benefit of a dense capillary network in the lungs with regard to gas exchange.

Answer 7

• Capillaries are organised side by side to each other.
• This promotes gas and blood sheet flow.
• Enhancing gas exchange.

Question 8

Explain how gas exchange occurs in the alveoli.

Answer 8

• Alveolar oxygen pressure is greater than in the blood.
• So oxygen moves from the lungs to the blood.
• Blood CO2 pressure is greater than in the lungs.
• So CO2 moves from the blood to the lungs.

Question 9

What is systemic gas exchange?

Answer 9

• The movement of gases via diffusion.
• Between the blood and the cells of the body.

Question 10

Outline the methods of oxygen transportation.

Answer 10

• 99% of O2 is carried via oxyhaemoglobin.
• Myoglobin shuttles O2 from the sarcolemma to the mitochondria + has a greater binding affinity than haemoglobin.

Question 11

Outline the methods of carbon dioxide transportation.

Answer 11

• 10% of CO2 is dissolved in blood.
• 20% of CO2 is carried via carbominohaemoglobin.
• 70% of CO2 is carried via bicarbonate ions.

Question 12

How many oxygen molecules can bind to haemoglobin?

Answer 12

4.

Question 13

Explain the oxygen-haemoglobin dissociation curve.

Answer 13

• A greater pressure of O2 in the blood means there is a greater saturation of haemoglobin with oxygen.
• When leaving the lungs due to the greater partial pressure.
• There will be a near-complete binding of haemoglobin with O2.
• If it available this binding will occur to enable gas exchange.

Question 14

Explain how the oxygen-haemoglobin dissociation curve changes in exercise conditions.

Answer 14

• Accumulating CO2 + changes in pH will shift the curve.
• This impacts O2’s ability to bind to haemoglobin.
• And drives oxygen offloading into tissues.

Question 15

What can cause this negative change in the oxygen-haemoglobin dissociation curve?

Answer 15

• Increased hydrogen ions.
• Increased CO2.
• Increased temperature.