Topic 3: Mass Transport In Animals

Question 1

Describe the structure haemoglobin

Answer 1

Haemoglobin is a protein with a quaternary structure.
It has 4 haem groups, containing iron

Question 2

Describe the oxyhaemoglobin dissociation curve

Answer 2

Oxygen is loaded in regions with high partial pressure of oxygen (eg.alveoli) and is unloaded in regions of low partial pressure of oxygen (eg.respiring tissues).
This is shown in the oxyhaemoglobin dissociation curve

Question 3

Explain cooperative binding

Answer 3

The affinity haemoglobin has for oxygen changes depending on how many oxygen molecules are already associated with it.
Haemoglobin can associate with four oxygen molecules and as each molecule binds, the shape of haemoglobin changes making the binding on further oxygen molecules easier.
Therefore, in areas with high pariah pressure of oxygen meaning a high concentration, the affinity of haemoglobin for oxygen is high and it loads more oxygen.
In humans, the alveoli have a high partial pressure of oxygen and therefore haemoglobin will readily load with oxygen here

Question 4

What is the Bohr effect?

Answer 4

The Bohr effect is when a high carbon dioxide concentration causes the oxyhaemoglobin curve to shift to the right.
The affinity for oxygen decreases because the acidic carbon dioxide changes the shape of haemoglobin slightly.
When carbon dioxide dissolves in liquid, carbonic acid forms and this decrease in pH changes the shape of haemoglobin slightly, which is why the affinity for oxygen decreases.
In respiring tissues, this is advantageous, as the haemoglobin delivers the oxygen to the site of respiring cells so that aerobic respiration can continue

Question 5

Explain why mammals require a double circulatory system

Answer 5

To manage the pressure of blood flow.
The blood flows through the lungs at a lower pressure.
This prevents damage to the capillaries in the alveoli and also reduces the speed at which the blood flows, enabling more time for gas exchange.
The oxygenated blood from the lung then goes back through thr heart to be pumped out at a higher pressure to the rest of the body.
This is important to ensure that the blood reaches all the respiring cells in the body

Question 6

Name the major blood vessel attached to the following organs

Answer 6

1. Heart (vena cava,aorta,pulmonary artery and pulmonary vein)
   2.Lungs (pulmonary artery and pulmonary vein)
   3.kidneys (renal artery and renal vein

Question 7

Tissue fluid is the liquid that surrounds cells. What does it contain ?

Answer 7

1.water
2.glucose
3.amino acids
4.fatty acids
5.ions
6.oxygen

Question 8

Describe the arteries

Answer 8

Muscle layer: thicker than veins so that constriction and dilation can occur to control volume of blood
Elastic layer: thicker than veins to help maintain blood pressure. The walls can stretch and recoil in response to the heart beat
Wall thickness: thicker wall than veins to help prevent the vessels bursting fur to the high pressure
Valves: no

Question 9

Describe the arterioles

Answer 9

Muscle layer: thicker than in the arteries to help restrict blood flow into the capillaries
Elastic layer: thinner than in arteries as the pressure is lower
Wall thickness: thinner as pressure is slightly lower
Valves: no

Question 10

Describe the veins

Answer 10

Muscle layer: relatively thin so it can’t control the blood flow
Elastic layer: relatively thin ad the pressure is much lower
Wall thickness: thinner as the pressure is much lower so there is low risk of bursting. The thinness means the vessels are easily flattened, which helps the flow of blood up to the heart
Valves : yes

Question 11

Describe the capillaries

Answer 11

Muscle layer: no muscle later
Elastic layer: no elastic layer
Wall thickness: one cell thick consisting of only a lining layer. This provides a short diffusion distance for exchanging materials between the blood and cells
Valves: no