Gas Transport in the Blood

Question 1

What happens to O2 in the respiratory system?

Answer 1

O2 is picked up by blood at the lungs and must be transported in the blood to the tissues for cellular use.

Question 2

What happens to CO2 in the respiratory system?

Answer 2

CO2 is produced at tissues and must be transported in the blood to the lungs for removal from the body

Question 3

What happens to PaO2 in the body?

Answer 3

It decreases from the passage from the atmosphere to the tissues.

Question 4

What is Henrys law?

Answer 4

The amount of a given gas dissolve in a given type and volume of liquid at a constant temperature is proportional to the partial pressure of the gas in equilibrium.

Question 5

What does henrys law mean?

Answer 5

If the partial pressure in the gas phase is increased the concentration of the gas in the liquid phase would increase proportionally

Question 6

What is the partial pressure of a gas in solution?

Answer 6

The partial pressure in the gas mixture with which the solution is in equlibrium

Question 7

How much does O2 consumption increase during strenuous exercise?

Answer 7

It may increase up to 25 fold during strenuous exercise

Question 8

What transports O2 in the blood?

Answer 8

Haemolglobin

Question 9

What two forms is O2 present in the blood?

Answer 9

1. Bound to haemoglobin

2. Physically disosolved

Question 10

How many haem groups are present in a haemoglobin molecule?

Answer 10

4

Question 11

When is haemoglobin considered fully saturated?

Answer 11

When all of the haemoglobin molecules in the blood are carrying their maximum O2 load.

Question 12

What is a primary factor in determining the percentage saturation of Hb with O2?

Answer 12

The partial pressure of O2

Question 13

What are the two chains called in the haemoglobin molecule?

Answer 13

Alpha chain and Beta chain

Question 14

At what kPa value is haemoglobin fully saturated?

Answer 14

13.3 kPa

Question 15

What is the oxygen delivery index?

Answer 15

A function of oxygen content of arterial blood and cardiac output.

Question 16

What is the oxygen content for arterial blood determined by?

Answer 16

The haemoglobin concentration and the saturation of Hb with O2.

Question 17

What is the equation for the oxygen delivery index?

Answer 17

Oxygen delivery index = oxygen content of arterial blood x Cardiac index

Question 18

What is the equation for the oxygen content of arterial blood?

Answer 18

Oxygen content of arterial blood = 1.34 x [Hb] x SaO2

Question 19

Name three factors that can impair oxygen delivery to the tissues?

Answer 19

Respiratory disease
Heart failure
Anaemia

Question 20

What is the equation for the partial pressure of oxygen in the alveolar air?

Answer 20

Partial pressure of O2 in alveolar air = partial pressure of O2 in inspired air - (Partial pressure of CO2 in arterial blood / 0.8)

Question 21

What is the oxygen content of arterial blood? 🩸

Answer 21

Arterial oxygen content is the sum of oxygen bound to haemoglobin and oxygen carried in physical solution in the blood.

Question 22

How is oxygen delivery to the tissues impaired by respiratory disease?

Answer 22

This decreases arterial PO2 and hence decreases the hb saturation with O2 and the O2 content of the blood.

Question 23

How is oxygen delivery to the tissues impaired by anaemia?

Answer 23

This decreases haemoglobin concentration and hence decreases oxygen content of the blood.

Question 24

How is oxygen delivery to the tissues impaired by heart failure?

Answer 24

This decreases cardiac output.

Question 25

What happens when one molecule of oxygen is bound to the haemoglobin molecule?

Answer 25

This increases the affinity of haemoglobin for oxygenthe by other subunits.

Question 26

What do the flat upper portions of the sigmoid curve o harmoglobin saturation?

Answer 26

A moderate fall in alveolar partial oxygen pressure will not much affect oxygen loading because the affinity is already high due to co-operativity.

Question 27

What do the steep lower portions of the sigmoid curve o harmoglobin saturation?

Answer 27

The peripheral tissues get a lot of oxygen for a small drop in capillary partial oxygen pressure because the affinity is lower due to co-operativity

Question 28

What is the name of the effect that shifts the curve to the right?

Answer 28

Bohr effect

Question 29

How does foetal haemoglobin differ from adult haemoglobin?

Answer 29

Foetal haemoglobin has two alpha subunits and two gamma subunits. Adult haemoglobin has two alpha subunits and two beta subunits.

Question 30

How does the affinity for oxygen compare between foetal haemoglobin and adult haemoglobin?

Answer 30

The affinity of foetal is haemoglobin higher than adult haemoglobin meaning the sigmoidal curve shifts left. This would allow oxygen to transfer from mother to foetus even if partial oxygen pressure is low.

Question 31

Where is myoglobin present?

Answer 31

In skeletal and cardiac muscles.

Question 32

How many ham groups are present on a myoglobin molecule?

Answer 32

One

Question 33

What is the purpose of myoglobin?

Answer 33

To provide short-term storage oxygen of for anaerobic conditions. It's presence indicates muscle damage.

Question 34

What are the means of carbon dioxide transport in the blood?

Answer 34

10% is in solution. 60% is as bicarbonate. 30% is as carbamino compounds (mainly CO2 with amino groups)

Question 35

How much more soluble is carbon dioxide than oxygen?

Answer 35

20 times

Question 36

What enzyme forms bicarbonate in the blood?

Answer 36

Carbonic anhydrase

Question 37

How are carbamino compounds formed?

Answer 37

Combination of carbon dioxide with terminal aminein blood proteins. Especially to globin inhaemoglobin to give carbamino-haemoglobin. This is rapid, even without an enzyme.

Question 38

What is the haldane effect?

Answer 38

Removing oxygen from haemoglobin increases the ability of haemoglobin to pick up carbon dioxide and carbon dioxide generated H+

Question 39

What does the Boher effect facilitate?

Answer 39

Oxygen liberation.

Question 40

What does the haldane effect facilitate?

Answer 40

Uptake of carbon dioxide and carbon dioxide generated H+

Question 41

What does the pick up of oxygen by haemoglobin do to its ability to bind carbon dioxide and H+

Answer 41

It weakens its ability