Mass Transport

Question 1

Structure of haemoglobin

Answer 1

Globular,water soluble. Consists of a polypeptide chains , each carrying a haem group (quaternary structure)

Question 2

Role of haemoglobin

Answer 2

Present in red blood cells. O2 binds to the haem groups and are carried around the body to where they are needed in respiring tissues.

Question 3

3 types of haemoglobin

Answer 3

Myoglobin
Adult haemoglobin
Fetal haemogobin

Question 5

3 factors affecting oxygen-haemoglobin binding

Answer 5

1. Partial pressure/concentration of O2
2. Partial pressure/concentration of CO2
3. Saturation of haemoglobin with oxygen

Question 6

How does partial pressure of oxygen affect oxygen-haemoglobin binding?

Answer 6

As partial pressure of O2 also increases, so oxygen binds tightly to haemoglobin.

When partial pressure is low oxygen is released from haemoglobin

Question 7

How does partial pressure of oxygen affect oxygen-haemoglobin binding?

Answer 7

As partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin.

When partial pressure is low oxygen is released from haemoglobin

Question 8

How does partial pressure of carbon dioxide affect oxygen-haemoglobin binding?

Answer 8

As partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape.

The affinity of haemoglobin for O2 therefore decreases , so oxygen is released from haemoglobin. This is known as the Bohr effect.

Question 9

How does saturation of haemoglobin with oxygen affect oxygen-haemoglobin binding?

Answer 9

It is hard for the first oxygen molecule to bind.

Once it does, it changes the shape to make it easier for the second and third molecules to bind, known as positive cooperativity.

It is then slightly harder for the fourth oxygen molecule to bind because there is a low chance of finding a binding site

Question 10

Explain why o2 binds to haemoglobin in the lungs

Answer 10

1. Partial pressure of O2 is high
2. Low concentration of CO2 in the lungs, so affinity is high
3. Positive cooperativity (bidnign becomes easier after the first O2 binds)

Question 11

Explain why O2 is released from haemoglobin in respiring tissues

Answer 11

1. Partial pressure of O2 is low
2. High conc. of CO2 in respiring tissues, so affinity decreases.

Question 12

What does it mean if the oxyhaemoglobin curve shifts to the right

Answer 12

High partial pressure of CO2 at respiring tissues

Decrease of affinity and there unloads more O2

Question 13

What does it mean if the oxyhaemoglobin curve shifts to the left

Answer 13

Low partial pressure of CO2 in the alveoli

Increase in affinity and therefore uploads more O2

Question 14

Why do animals have different types of haemoglobins

Answer 14

Different types of haemoglobins have different affinities for O2 which is an adaptation to their environment.

Question 15

What is tissue fluid?

Answer 15

Fluid containing water, glucose , amino acids and fatty acids which bathes the tissue

Question 16

How is tissue formed?

Answer 16

As blood enters the capillaries from the ARTERIOLES, the smaller diameter results in a HIGH HYDROSTATIC PRESSURE, so water, glucose, amino acids, fatty acids, ions, and oxygen are forced out. This is known as ultrafiltration.

Question 17

What remains in the capillary after tissue fluid is pushed out

Answer 17

Red blood cells
Platelets
Large proteins

Question 18

How is tissue fluid reabsorbed ?

Answer 18

Large molecules that remain in the capillaries and lower water potential. Towards the venule end of the capillaries, the hydrostatic pressure is lowered due to the loss of liquid. So water re-enter the capillaries by osmosis