Haemoglobin and gas transport

Question 1

what is blood’s oxygen carrying capacity without haemoglobin?

Answer 1

3ml/L

Question 2

what is blood’s oxygen carrying capacity with haemoglobin?

Answer 2

200ml/L

Question 3

what is partial pressure?

Answer 3

the pressure of a substance in solution, this pressure is equal to the pressure in the gaseous phase that results in the concentration in the liquid phase

Question 4

what oxygen saturation is deoxygenated venous blood?

Answer 4

75%

Question 5

does oxygen bind loosely or tightly to haem groups?

Answer 5

loosely

Question 6

what are the 4 types of haemoglobin

Answer 6

-HbA most abundant
-HbA2
-HbF
glycosylated Hb

Question 7

what is the major determinant for the degree of haemoglobin saturation?

Answer 7

partial pressure of oxygen in arterial blood (this is determined by alveolar partial pressure so this indirectly determines saturation)

Question 8

how is the partial pressure gradient maintained at the alveoli?

Answer 8

the oxygen moves into the arterial blood then binds to haemoglobin, removing it from solution and maintaining a low PP in solution

Question 9

what shape is the oxygen-haemoglobin dissociation curve?

Answer 9

sigmoidal

Question 10

what does the sigmoidal oxygen-haemoglobin dissociation curve tell us about the Hg saturation at PP of oxygen of 100 to 60 mmHg?

Answer 10

when the PP is high a small decrease in PP doesn’t cause a large decrease in saturation, as there is a plateau it stays relatively constant

Question 11

why does feotal haemoglobin have a higher affinity than HgA ?

Answer 11

it means that a feotus is able to strip oxygen from the mother’s haemoglobin in utero

Question 12

why does myomoglobin have a higher affinity than HgA ?

Answer 12

so that it can strip oxygen from HgA in the blood when the skeletal muscle it is contained in is working hard.

Question 13

what is anaemia?

Answer 13

any condition where the oxygen carrying capacity of the blood is compromised

Question 14

what are some examples of anaemia causing conditions?

Answer 14

iron deficiency, haemorrhage, vit B12 deficiency

Question 15

what would the partial pressure of oxygen be in arterial blood in someone with anaemia?

Answer 15

normal (40mmHg).

so anaemics have normal PP of oxygen but lowered total blood oxygen content

Question 16

what would the sturation of haemoglobin be in an anaemic?

Answer 16

normal (100%)

Question 17

what does acidosis do to haemoglobin’s affinity for oxygen/

Answer 17

it decreases it, dissociation curve shifts to right

Question 18

what does alkalosis do to haemoglobin’s haemoglobin’s affinity for oxygen?

Answer 18

increases it, dissociation curve shifts to left

Question 19

what does an increase in partial pressure of carbon dioxide do to haemoglobin’s affinity for oxygen?

Answer 19

It causes it to decrease

Question 20

what does a decrease in partial pressure of carbon dioxide do to haemoglobin’s affinity for oxygen?

Answer 20

it increases it

Question 21

what does an increase in temperature do to haemoglobin’s affinity for oxygen

Answer 21

causes it to decrease

Question 22

what does a decrease in temperature do to haemoglobin’s affinity for oxygen

Answer 22

causes it to increase

Question 23

what is 2, 3-DPG?

Answer 23

2, 3-diphosphoglycerate, it is produced by RBCs when the metabolise in hypoxic condions

Question 24

what does an increase in 2, 3-DPG do to Hg’s affinity for oxygen?

Answer 24

it causes it to decrease

Question 25

what does a decrease in 2, 3-DPG do to Hg’s affinity for oxygen?

Answer 25

it causes it to increase

Question 26

why is carbon monoxide a poison?

Answer 26

it has a much higher affinity for Hg than oxygen so it binds and doesn’t unbind this means oxygen cant be transported round the body

Question 27

what are the symptoms of carbon dioxide poisoning?

Answer 27

Hypoxia and anaemia, nausea and headaches, cherry red skin and mucous membranes. Respiration rate unaffected due to normal arterial PCO2. Potential brain damage and death.

Question 28

what are the 5 main types of hypoxia?

Answer 28

• Hypoxaemic Hypoxia
• Anaemic Hypoxia
• Stagnant Hypoxia
• Histotoxic Hypoxia
• Metabolic Hypoxia

Question 29

what is hypoxaemic hypoxia?

Answer 29

Reduction in O2 diffusion at lungs either due to decreased PO2atmos or tissue pathology. (most common type of hypoxia)

Question 30

what is anaemic hypoxia?

Answer 30

Reduction in O2 carrying capacity of blood due to anaemia (red blood cell loss/iron deficiency).

Question 31

what is stagnant hypoxia?

Answer 31

Heart disease results in inefficient pumping of blood to lungs/around the body

Question 32

what is histotoxic hypoxia?

Answer 32

poisoning prevents cells utilising oxygen delivered to them e.g. carbon monoxide/cyanide

Question 33

what is metabolic hypoxia?

Answer 33

oxygen delivery to the tissues does not meet increased oxygen demand by cells.

Question 34

what is the treatment for CO poisoning?

Answer 34

give 100% oxygen to increase PP of oxygen in arteries

Question 35

how is carbon dioxide absorbed into the blood?

Answer 35

7% remains dissolved in plasma and erythrocytes,
23% combines in the erythrocytes with deoxyhemoglobin to form carbamino compounds
70% combines in the erythrocytes with water to form carbonic acid, which then dissociates to yield bicarbonate and H+ ions

Question 36

what is the main way in which carbon dioxide is transported?

Answer 36

it combines in the erythrocytes with water to form carbonic acid, which then dissociates to yield bicarbonate and H+ ions. Most of the bicarbonate then moves out of the erythrocytes into the plasma in exchange for Cl- ions (chloride shift) & the excess H+ ions bind to deoxyhemoglobin

Question 37

what causes respiratory acidosis?

Answer 37

hypoventilation

Question 38

what causes respiratory alkalosis?

Answer 38

hyperventilation