Gas Transport

Question 0

When hb is 100% saturated how does 1g of hb carry ?

Answer 0

1.34 ml

Question 1

Describe the structure of haemoglobin

Answer 1

Protein in rbcs
Has 4 subunits each with a haem group each containing an iron ion that can bind 1 oxygen molecule
Adult hb= 2 alpha and 2 beta subunits
Feral hb= 2 alpha and 2 gamma

Question 2

What is the normal concentration of hb in blood ?

Answer 2

120-170g/L

So oxygen carry capacity of hb in blood is 200ml

Question 3

If CO is 5l/mins how much oxygen is delivered around the blood in 1 min ?

Answer 3

1L

- resting oxygen consumption is 250ml so remaining 750ml returns to lungs - large reserve of oxygen bound

Question 4

What shaped is the hb-oxygen dissociation curve and why ?

Answer 4

Sigmoidal
Binding of 1 oxygen molecule changes the conformation of hb and increases the affinity of the other oxygen binding so it is easily to bind another molecule

Question 5

If a factor decreases hbs affinity for oxygen which way does the curve shift ?

Answer 5

Right

Question 6

Anything that increases hb affinity for oxygen shifts curve to the ..,

Answer 6

Left

Question 7

How does temperature affect hb affinity for oxygen ?

Answer 7

Increase in temperature decreases oxygen affinity
Good because during metabolism heat is produced so increasing the temperature will favour oxygen unloading which is what the tissue needs

Question 8

How does pH affect hb affinity for oxygen ?

Answer 8

Decrease in pH decreases affinity for oxygen

Good because during metabolism proton concentration. Increases so increasing oxygen unloading is favourable

Question 9

How does carbon dioxide (carbamino effect) effect hb affinity for oxygen ?

Answer 9

Increases in carbon dioxide decreases oxygen affinity

Carbon dioxide binds to amino acids in hb and creates caraminohaemoglobin which has a lower affinity for oxygen

Question 10

How does 2,3-DPG affect hb affinity for oxygen ?

Answer 10

Oxyhemoglobin inhibits enzyme that produces 2,3-DPG
When oxygen levels are reduced 2,3-DPG levels rise and decrease affinity of hb for oxygen which is good because 2.3-DPG is produced during high metabolism so the tissue will be requiring oxygen

Question 11

What is the difference between fetal and maternal hb ?

Answer 11

Fetal has a higher affinity for oxygen because it has 2 gamma subunits instead of beta

Question 12

What is the purpose of myoglobin ?

Answer 12

Short term store of oxygen in skeletal muscle
Much higher affinity for oxygen than hb
Releases its stores when intracellular oxygen is low - used in short intense muscle contraction

Question 13

What are the 3 transport mechanisms for carbon dioxide in blood ?

Answer 13

Dissolved in plasma
Dissolved in the form of bicarbonate ions
Bound to hb

Question 14

What enzyme catalyses the reaction converting carbon dioxide to bicarbonate ions ?

Answer 14

Carbonic anhydrase

Question 15

What is the chloride shift ?

Answer 15

When bicarbonate ions are produced protons are also produced in the rbcs
To maintain the concentration gradient so more carbon dioxide is converted to bicarbonate ions the bicarbonate ions are exchanged for a chloride ions

Question 16

What is the haldane effect ?

Answer 16

Binding of oxygen to hb reduces affinity of hb for carbon dioxide
The greater the partial pressure of oxygen the more carbon dioxide is unloaded so therefore this effect increases elimination of carbon dioxide at the lungs
Effect is beneficial at respiring tissues because oxygen is low which promotes carbon dioxide binding helping to remove carbon dioxide

Question 17

What is anaemia ?

Answer 17

Decrease in oxygen carrying capacity of the blood

Question 18

What is nutritional anaemia ?

Answer 18

Dietary deficiency - iron or folic acid
Causes a decrease in hb synthesis - iron
Inhibits DNA synthesis and cell division- folic acid

Question 19

What is pernicious anaemia?

Answer 19

Deficiency of intrinsic factor needed to absorb bit b12 - inhibits DNa synthesis

Question 20

What is aplastic anaemia?

Answer 20

Defect in bone marrow

Question 21

What is renal anaemia ?

Answer 21

Decreased EPO resulting in decreased red blood cell synthesis

Question 22

What is haemorrhagic anaemia ?

Answer 22

Rapid loss of blood - takes weeks to restore red blood cell levels

Question 23

What is haemolytic anaemia ?

Answer 23

Caused by rupture of red blood cells - malaria or sickle cell anaemia