Lectures 6 & 7

Question 1

How much oxygen is dissolved in each litre of plasma?

Answer 1

3ml

Question 2

What does haemoglobin do to the oxygen carrying capacity?

Answer 2

Increase it from 3ml/L to 200ml/L

Question 3

How is CO2 mainly transported around the body?

Answer 3

As bicarbonate in red blood cells

Question 4

What is the difference between arterial partial pressure of oxygen and oxygen content?

Answer 4

Arterial partial pressure only deals with oxygen in solution whilst oxygen content also includes oxygen bound to haemoglobin

Question 5

What is arterial partial pressure of oxygen determined by?

Answer 5

Solubility of water and the partial pressure of the oxygen in the gaseous phase that is driving oxygen into solution

Question 6

How much of the arterial oxygen is extracted by peripheral tissue at rest?

Answer 6

25%

Question 7

How much oxygen is dissolved in plasma in the arterial blood?

Answer 7

Less than 2%

Question 8

What is the partial pressure of oxygen in the plasma determined by?

Answer 8

How much oxygen binds to haemoglobin

Question 9

What is the reserve capacity of PO2?

Answer 9

75% in normal venous blood

Question 10

What is foetal haemoglobin?

Answer 10

A type of haemoglobin that is produced at the foetal stage primarily but is still produced through adulthood. It has a higher affinity for oxygen than adult haemoglobin so that a foetus can take oxygen from its mother

Question 11

Where is myoglobin found?

Answer 11

In muscle cells

Question 12

What is anaemia?

Answer 12

A condition where the oxygen carrying capacity of the blood is compromised (e.g. iron deficiency, haemorrhage, vit B12 deficiency)

Question 13

What is the effect of anaemia on PO2?

Answer 13

No effect because it only effects oxygen uptake by haemoglobin not oxygen in solution

Question 14

What is the effect of increased pH, PCO2, temperature and DPG (diphosphoglycerate)?

Answer 14

Haemoglobin’s affinity for oxygen decreases so it releases oxygen more readily which is taken up by cells so they can get the oxygen they need

Question 15

what is the effect of carbon monoxide?

Answer 15

Binds to to form carboxyhaemoglobin with an affinity 250 times greater than O2 but dissociates very slowly so is a big problem as soon as it is dissolved in the circulation. It takes up oxygens place so less oxygen gets to cells

Question 16

What are the 5 main types of hypoxia?

Answer 16

Hypoxic hypoxia 
Anaemic hypoxia 
Ischaemic hypoxia 
Histotoxic hypoxia 
Metabolic hypoxia

Question 17

What type of hypoxia is the most common?

Answer 17

Hypoxic hypoxia

Question 18

What is the main way that carbon dioxide is transported in the blood?

Answer 18

By combining with water to form carbonic acid, dissociating into bicarbonate and hydrogen ions. The bicarbonate leaves the erythrocyte into the plasma in exchange for chlorine ions and the excess hydrogen ions bind to deoxyhaemoglobin

Question 19

What is the effect of hyper and hypoventilation?

Answer 19

Hypoventilation, causing CO2 retention, leads to increased [H+] bringing about respiratory acidosis.

Hyperventilation, blowing off more CO2, lead to decreased [H+] bringing about respiratory alkalosis

Question 20

What does an increased PCO2 do?

Answer 20

Increases hydrogen ion concentration