Mass transport in animals

Question 1

What is haemoglobin and its structure?

Answer 1

Protein with a quaternary structure (EA)
A quaternary structure is when it consists of more than 1 polypeptide chain. Haemoglobin contain a haem group where oxygen binds. Each haem group has an iron ion (Fe2+) that gives haemoglobin its red colour.

Question 2

Where does oxygen bind onto in haemoglobin?

Answer 2

Onto the haem group.

Question 3

What does affinity of haemoglobin for oxygen mean?

Answer 3

The ability of haemoglobin to attract or bind oxygen

Question 4

What does saturation of haemoglobin with oxygen mean?

Answer 4

When haemoglobin is holding the maximum amount of oxygen it can

Question 5

What does loading / association of haemoglobin mean?

Answer 5

The binding of oxygen to haemoglobin

Question 6

What does unloading/ disassociation of haemoglobin mean?

Answer 6

When oxygen unbinds from haemoglobin.

Question 7

What does the oxyhaemoglobin disassociation graph show?

Answer 7

It shows that at a high partial pressure of oxygen, haemoglobin will be almost completely saturated with oxygen. This means that oxygen is loaded in regions with a high partial pressure of oxygen e.g. lungs (alveoli). At lower partial pressures of oxygen, haemoglobin isn’t as saturated and therefore has a low affinity and will not attract oxygen efficiently. This means that oxygen is unloaded in regions with a low partial pressure of oxygen e.g. respiring tissues.

Question 8

Why is it an advantage if oxygen is unloaded into regions with a low partial pressure of oxygen?

Answer 8

The haemoglobin is unloading the oxygen at sites where it is needed such as respiring tissues.

Question 9

What is partial pressure?

Answer 9

The measure of the concentration of a particular gas in a mixture of gases or liquids.

Question 10

What is cooperative binding?

Answer 10

When each molecule of oxygen binds, it changes the shape of the haemoglobin in a way that makes it easier for further oxygen molecules to bind.

Question 11

Why is the oxyhaemoglobin disassociation graph an s-shape.

Answer 11

Because the increasing partial pressure of oxygen is not linear to the saturation of haemoglobin. This is because as the saturation of haemoglobin increases, it makes it harder for the final oxygen molecules to bind because there is already enough.

Question 12

What is the Bohr effect?

Answer 12

When carbon dioxide is released by respiring cells, the affinity of haemeoglobin for oxygen decreases. Carbon dioxide creates slightly acidic conditions which change the shape of the haemoglobin protein, thus making it easier for the oxygen to be released. This shifts the curve to the right.

Question 13

Describe the muscle the heart is made up of.

Answer 13

Cardiac muscle
- Thick muscular layer
- It is myogenic which means it can contract and relax without nervous or hormonal stimulation
- It never fatigues, as long as it has a supply of oxygen

Question 14

Describe the coronary arteries.

Answer 14

• Blood vessels that surround the heart and supply the cardiac muscle with oxygenated blood.
• They branch off from the aorta.

Question 15

What happens in coronary arteries become blocked?

Answer 15

The cardiac muscle will not receive any oxygen therefore the cells will not be able to respire and die. This results in a myocardial infraction (heart attack)

Question 16

What are features of the atria?

Answer 16

Thin muscular walls because they do not need to contract as hard since they are not pumping blood far.

Elastic walls to stretch when blood enters.

Question 17

What are the features of the ventricles?

Answer 17

Thicker muscular walls which creates a high blood pressure that allows blood to flow longer distances to the lungs and entire body

Question 18

Which ventricle out of the right and the left has thinner walls and why?

Answer 18

The right ventricle has thinner walls compared to the left ventricle because it pumps blood to the lungs which has to be at a low pressure to prevent damage to the capillaries in the lungs and so blood flows slowly to allow gas exchange to occur.

Question 19

What are the 4 major blood vessels in the heart?

Answer 19

• Right and left pulmonary artery
• Right and left pulmonary vein
• Aorta
• Vena cava

Question 20

Where do the 2 veins carry blood from and to?

Answer 20

Vena cava:
- Carries deoxygenated blood from the body into the right atrium

Pulmonary vein:
- Carries oxygenated blood from the lungs to the left atrium

Question 21

Where do the 2 arteries carry blood from and to?

Answer 21

Pulmonary artery:
- Carries deoxygenated blood from the right ventricle to the lungs to become oxygenated.

Aorta:
- Carries oxygenated blood from the left ventricle to the rest of the body.

Question 22

Name the valves in the heart and where they are found.

Answer 22

Semi-lunar valves:
- Between the ventricles and the arteries, found in the aorta and pulmonary vein.

Atrioventricular valves:
- Found between atria and ventricles.
- Bicuspid is left side, tricupsid is right

Question 23

What do valves do?

Answer 23

The open when the pressure is higher behind the valves and close when the pressure is lower in front of the valves to prevent the backflow of blood

Question 24

What are the 3 stages the cardiac cycle is split into?

Answer 24

Diastole
Atrial systole
Ventricular systole

Question 25

Explain diastole.

Answer 25

• The atria and ventricular muscles are relaxed.
• The blood will enter into the atria via the vena cava and pulmonary vein.
• The blood flowing into the atria will cause the pressure in the atria to increase

Question 26

Explain atrial systole.

Answer 26

• The ventricular walls are still relaxed.
• The atria muscular walls will contract which further increases the pressure in the atria.
• This causes the atrioventricular valves to open to allow blood to flow into the ventricles.

Question 27

Explain ventricular systole.

Answer 27

• After a short delay, the ventricle muscular walls will contract which creates a very high pressure in the ventricles.
• This high pressure forces the atrioventricular valves to close and the semi-lunar valves to open.
• Blood is pushed out of the ventricles and into the aorta and pulmonary artery.

Question 28

What causes atrioventricular valves to open and close?

Answer 28

Open - If pressure is higher in atria compared to ventricles.
Close - If pressure is higher in the ventricles compared to the atria

Question 29

What causes semi-lunar valves to open and close?

Answer 29

Open - If pressure is higher in ventricles compared to arteries
Close - If pressure is higher in arteries compared to ventricles

Question 30

Describe what the circulatory system is in mammals.

Answer 30

Mammals have a closed, double circulatory system.
Closed - blood remains within the blood vessels.
Double circulatory - blood passes through the heart twice, once to deliver blood to the lungs and another to deliver blood to the body.

Question 31

Why do mammals have a double circulatory system?

Answer 31

To manage the pressure of the blood flow since the lungs and the body both require different pressure and to ensure that oxygenated and deoxygenated blood do not mix.

Question 32

What pressure of blood does the lungs require and why?

Answer 32

The blood flows through the lungs at low pressure to prevent damage to the capillaries and also flows slowly to allow more time for gas exchange to occur between the blood and capillaries.

Question 33

What pressure of blood does the body require and why?

Answer 33

Blood flows around the body at high pressure to ensure all the blood reaches the respiring cells.

Question 34

Describe the route that blood takes in the double circulatory system.

Answer 34

Blood flows through the lungs at a lower pressure. The oxygenated blood then goes from the lungs back to the heart to be pumped to the rest of the body.

Question 35

Name the key blood vessels associated with the circulatory system.

Answer 35

Heart - vena cava, pulmonary vein, pulmonary artery, aorta

Lungs - pulmonary artery and pulmonary vein

Kidney - renal artery and renal vein

Question 36

Explain the 2 circulations in the body.

Answer 36

Pulmonary circulation - transports blood to the lungs.

Systemic circulation - transports blood to the body tissues.

Question 37

Whats the function of arteries?

Answer 37

Carry blood away from the heart and into arterioles

Question 38

Whats the function of arterioles?

Answer 38

Arteries branch off into arterioles which are smaller than arteries and connect the arteries to the capillaries.

Question 39

Whats the function of capillaries?

Answer 39

Connect arterioles to veins

Question 40

Whats the function of veins?

Answer 40

Carry blood back into the heart.

Question 41

Compare the structure of arteries and veins.

Answer 41

Veins: Bigger lumen that has an irregular shape
Arteries: Smaller lumen, circular

Arteries: Thicker muscular layer to allow for constriction and dilation which controls the volume and pressure of blood flow
Veins: Thinner muscular layer which means no control over blood flow

Arteries: Thicker elastic layer which maintains the blood pressure and allows stretch and recoil into its original shape in response to a heartbeat. Prevents arteries from breaking under high pressure
Veins: Thinner elastic layer since they carry blood at a low pressure

Arteries: Thicker walls to help prevent the arteries from bursting due to blood flowing at high pressure
Veins: Thinner walls since the pressure of blood flow is low hence risk of bursting is low

Arteries: No valves
Veins: Valves

Question 42

Describe the structure of the capillaries

Answer 42

• One cell thick
• No muscle or elastic layer
• A red blood cell can only just fit through the diameter of the lumen which is an advantage because it slows the blood flow which maximises gas exchange in the capillaries and gives it more time to occur.

Question 43

Describe the structure of arterioles compared to arteries

Answer 43

• Has a thicker muscular layer than arteries to help restrict the blood flow into the capillaries. (too much blood=high pressure in capillaries)
• Thinner elastic layer than arteries since the pressure is lower
• Thinner walls than arteries since the pressure is lower
• No valves

Question 44

Explain how an arteriole can reduce the blood flow into capillaries.

Answer 44

The muscle will contract which narrows the lumen of the arteriole.