Carriage of oxygen and carbon dioxide

Question 1

Where are erythrocytes made?

Answer 1

In bone marrow to last 120 days

Question 2

What are adaptations of red blood cells?

Answer 2

No nucleus an biconcave shape

Question 3

What is the function of no nucleus?

Answer 3

Maximise space for haemoglobin

Question 4

What is the function of the biconcave shape?

Answer 4

Increases surface area for gas exchange and to pass through narrow capillaries

Question 5

What does the haem group have?

Answer 5

Affinity for oxygen

Question 6

What is loading?

Answer 6

Haemoglobin takes up the oxygen to form oxyhaemoglobin

Question 7

What is dissociation?

Answer 7

Oxyhaemoglobin giving up oxygen

Question 8

What release and uptake of oxygen?

Answer 8

Release and uptake of oxygen by haemoglobin which is not directly proportional to the % of oxygen in surroundings

Question 9

What is an oxygen dissociation curve?

Answer 9

Plotting how saturated with oxygen haemoglobin is against the oxygen partial pressure/tension in the surrounding blood

Question 10

What is the shape of an oxygen dissociation curve?

Answer 10

Sigmoidal (S)

Question 11

What is oxygen tension?

Answer 11

The relative pressure than oxygen is contributed to the pressure exerted by a mixture of gases

Question 12

What is oxygen tension measured in?

Answer 12

kPa

Question 13

What happens when oxygen tension raises?

Answer 13

The diffusion gradient improves so more oxygen combines with haemoglobin causing conformational change

Question 14

What is conformational change?

Answer 14

The haemoglobin molecule slightly changing shape

Question 15

What is the result of conformation change?

Answer 15

Positive coopererativity

Question 16

What is positive coopererativity?

Answer 16

Oxygen can more readily reach the insides of the haemoglobin and associate with the haem

Question 17

Why is it difficult to achieve 100% saturation?

Answer 17

Oxygen molecules become more difficult for oxygen to diffuse in and associate with last haem group

Question 18

How is mammalian haemoglobin adapted?

Answer 18

It is well adapted for becoming nearly 100% saturation in lungs when oxygen tension is high

Question 19

How are the tissues adapted for dissociation?

Answer 19

Relatively low pH

Question 20

What do active muscle cells contain?

Answer 20

Myoglobin

Question 21

How is myoglobin curve drawn?

Answer 21

It is on to the left of haemoglobin curve

Question 22

What does a more left curve symbolise?

Answer 22

A higher affinity for oxygen

Question 23

How is the foetal haemoglobin represented/

Answer 23

It is to left of mothers haemoglobin

Question 24

How is oxygen transferred from mum to foetus?

Answer 24

Foetal haemoglobin has higher oxygen affinity for oxygen than mothers

Question 25

What also effects oxygen dissociation?

Answer 25

pH and carbon dioxide

Question 26

What causes a left shift?

Answer 26

Lower carbon dioxide, higher pH and lower temperature

Question 27

What causes a right shift?

Answer 27

Higher carbon dioxide , lower pH and higher temperature

Question 28

What is the Bohr effect?

Answer 28

When partial pressure of carbon dioxide rises, haemoglobin gives oxygen up more readily

Question 29

How is carbon dioxide transported?

Answer 29

5% is dissolved in plasma, 10-20% is combined with amino groups of polypeptide chains and 75-85% is converted to hydrogen carbonate

Question 30

How is carbon dioxide combined with amino groups?

Answer 30

It is combined with amino groups of the polypeptide chains chains of the haemoglobin to make carbaminohaemoglobin

Question 31

How is carbon dioxide converted to hydrogen carbonate?

Answer 31

it is converted into ions in the cytoplasm of red blood cells and in the plasma which is then carried in plasma

Question 32

What does carbon dioxide form?

Answer 32

Carbonic acid

Question 33

How is carbonic acid formed?

Answer 33

Carbon dioxide reacts with water and carbonic amylase catalyses the reaction

Question 34

What happens to the carbonic acid inside red blood cells and plasma?

Answer 34

It dissociates to form hydrogen ions and hydrogencarbonate ions which move out red blood cell by diffusion

Question 35

What happens as a result of hydrogencarbonate ions diffusing out?

Answer 35

Chloride shift

Question 36

What is chloride shift?

Answer 36

Chloride ions move into red blood cells

Question 37

What happens to hydrogen ions?

Answer 37

Haemoglobin picks them up to prevent pH changing and forms haemoglobonic acid

Question 38

What is the purpose of haemoglobonic acid?

Answer 38

It helps oxygen to be released from the oxyhaemoglobin as the oxygen diffuses out of the red blood cells and into respiring tissue

Question 39

What happens to a small proportion of carbon dioxide?

Answer 39

It binds directly to the haemoglobin to form carbaminohaemoglobin

Question 40

What happens to carbonic acid in the lungs?

Answer 40

Carbonic anhydrase catalyses a reverse reaction to turn the carbonic acid back into water and carbon dioxide

Question 41

What happens to hydrogen carbonate ions at the lungs?

Answer 41

They diffuse back into the red blood cells reacting with hydrogen ions to form carbonic acid

Question 42

What happens to the chloride ions at the lungs?

Answer 42

They diffuse out of the red blood cells into plasma