Physiology 2 - Gas Exchange & Transport

Question 1

Tidal volume x Respiratory Rate = ~6L of what?

Answer 1

Pulmonary Ventilation

Question 2

(Tidal volume - anatomical dead space) x Respiratory rate = ~ 4.2L of what?

Answer 2

Alveolar Ventilation

Question 3

Name the number: ~ 0.15 ml

Answer 3

Anatomical Dead Space Volume

Question 4

Name the number: ~ 4.5L

Answer 4

Alveolar Ventilation

Question 5

Name the number: ~ 5L

Answer 5

Pulmonary Ventilation

Question 6

Which 4 factors influence rate of gas exchange across alveolar membrane?

Answer 6

Partial Pressure Gradients of O2 and CO2

Diffusion coefficient of O2 and CO2

Surface Area of Alveolar Membrane

Thickness of Alveolar Membrane

Question 7

Why is Dalton’s Law of Partial Pressures relevant to alveolar gas exchange?

Answer 7

Gaseous diffusion relies on pressure gradients, and the partial pressure of gas determines its pressure gradient.

Question 8

What does Fick’s Law of Diffusion tell us about O2 & Co2 alveolar diffusion?

hint: think of surface area and thickness

Answer 8

Lungs have a large surface area to allow more gas exchange (diffusion proportional to surface area)

and alveoli are thin walled structures (diffusion inversely proportional to membrane thickness)

Question 9

Which cell type lines the walls of the alveoli?

Answer 9

Type 1 alveoli

Question 10

Which law states that at constant temperature, a gas solubility is proportional to gas partial pressure?

Answer 10

Henry’s Law

Question 11

When the O2 Dissociation Curve shifts to the right, what is the name of this effect?

Answer 11

Bohr Effect

Question 12

What is the significance of the sigmoid shape of the O2 dissociation curve?

Answer 12

The sigmoid shows that a small drop in PO2 makes little difference to O2 saturation in pulmonary capillaries

BUT

A small drop in PO2 in tissues has a large effect on O2 saturation.

Question 13

How does foetal haemoglobin (HbF) differ in structure from adult Hb?

What is the consequence?

Answer 13

Foetal Hb has 2 alpha and 2 gamma subunits, so it interacts less with 2,3 - Biphosphoglycerate in RBCs, and has a higher affinity for O2.

This allows for O2 to transfer from mum to baby, even if PO2 is low.

Question 14

The myoglobin dissociation curve is hyperbolic, with 1:1 binding. Why is that useful?

Answer 14

Myoglobin releases O2 at very low PO2, and provides a short term storage of O2 in anaerobic conditions.

Question 15

Name 3 ways in which CO2 is transported in the blood?

Answer 15

60% Bicarbonate

30% Carbamino compounds

10% Solution

Question 16

What enzyme assists rapid inter-conversion of carbon dioxide and water into carbonic acid, protons and bicarbonate ions in RBCs?

Answer 16

Carbonic anhydrase

Question 17

What is the term which refers to the exchange of bicarbonate (HCO3−) and chloride (Cl−) across the membrane of red blood cells (RBCs)?

Answer 17

Chloride Shift

Question 18

What is the significance of a carbaminohaemoglobin?

Answer 18

Carbon dioxide binds to amino groups, creating carbaminohaemoglobin.

Increased carbaminohaemoglobin decreases O2 binding to Hb.

Question 19

Explain the Haldane Effect?

Answer 19

Removing O2 from Hb increases the ability of Hb to bind to CO2 and H+