1B Mammalian Transport

Question 1

What is a mass transport system?

Answer 1

arrangement of structures by which substances are transported with a fluid and a mechanism (e.g. pump) for moving it around the body

Question 2

Why is a mass transport system needed in larger organisms?

Answer 2

The surface area : volume ratio is too small to maintain effective diffusion.

Question 3

Describe a single circulatory system

Answer 3

The heart pumps blood to the organs of gas exchange (e.g. gills in fish) and then the blood travels to the rest of the body before returning to the heart

Question 4

Describe a double circulatory system

Answer 4

Circulation involves two separate circuits, one for deoxygenated blood moving from the heart to the gas exchange organs and one for oxygenated blood flowing around the body before returning to the heart.

Question 5

What are the 4 components of blood?

Answer 5

Red blood cells (erythrocytes), white blood cells (leucocytes), plasma and platelets

Question 6

What is the function of the red blood cells?

Answer 6

To transport oxygen from the lungs to the respiring cells.

Question 7

How are red blood cells adapted to their function?

Answer 7

No nucleus - more space for haemoglobin means more oxygen can be carried
Biconcave shape - large surface area : volume ratio for rapid diffusion of oxygen

Question 8

What is the function of plasma?

Answer 8

It transports blood cells and other dissolved substances, including waste products (e.g. glucose, urea, hormones, carbon dioxide).
It also helps to maintain steady body temperature and acts as a buffer to regulate pH changes.

Question 9

What is the function of the white blood cells?

Answer 9

To defend the body against infection

Question 10

How are white blood cells adapted to their function?

Answer 10

Can change their shape - they squeeze through the blood vessel walls to get to pathogens and the can engulf pathogens

Question 11

What is the function of the platelets?

Answer 11

Blood clotting - prevent blood loss and minimise risk of pathogens entering the body

Question 12

How is oxygen transport in the blood?

Answer 12

As oxyhaemoglobin, combined with haemoglobin in the red blood cells

Question 13

Describe and explain the shape of the oxygen dissociation curve for haemoglobin.

Answer 13

S-shaped curve. As partial pressure of oxygen increases, haemoglobin saturation increases. Each haemoglobin molecule can bind to 4 oxygen molecules - the first is relatively easy to bind, this changes the shape of the haemoglobin, making it easier for molecules 2 and 3 to bind, then molecule 4 is harder because the haemoglobin is “full”

Question 14

What are the 3 ways carbon dioxide can be transported in the blood?

Answer 14

Carried dissolved in the blood plasma, combined with haemoglobin as carbaminohaemoglobin and in the cytoplasm of red blood cells as hydrogencarbonate ions.

Question 15

What does the Bohr Effect relate to?

Answer 15

The that carbon dioxide concentration affects the affinity of haemoglobin for oxygen.

Question 16

Describe the Bohr Effect.

Answer 16

As the concentration of carbon dioxide rises (e.g. in respiring tissues), the affinity of haemoglobin for oxygen is reduced. This makes it easier for the haemoglobin to release oxygen, allowing it to move to the respiring tissues where it is needed.

Question 17

Outline the blood clotting process.

Answer 17

Damage to the blood vessel wall exposes the collagen. This stimulates the release of thromboplastin. Thromboplastin, with calcium ions, catalyses the conversion of prothrombin into thrombin. Thrombin stimulates the conversion of fibrinogen into fibrin. Fibrin creates a mesh that covers the wound, trapping other blood cells to strengthen the layer.

Question 18

Describe the structure of arteries.

Answer 18

Small lumen, smooth endothelium, thick wall with elastic fibres and muscle tissue.

Question 19

How is the structure of an artery related to its function?

Answer 19

Smooth endothelium for easy blood flow, thick elastic layer for stretch and recoil, muscle tissue contracts and relaxes to change the size of the lumen - the smaller the lumen, the higher the pressure.

Question 20

Describe the structure of a vein

Answer 20

Veins have valves, relatively large lumen, smooth endothelium lining, outer layer of collagen, thin layer of muscle and some elastic fibres.

Question 21

How is the structure of a vein related to its function?

Answer 21

Smooth endothelium lining for easy blood flow, the large lumen means blood is under low pressure, so valves prevent backflow of blood. Low pressure means less need for muscular and elastic layer.

Question 22

Describe the structure of a capillary

Answer 22

Very small lumen (just bigger than a red blood cell), very thin walls - just one epithelial cell thick.

Question 23

How is the structure of a capillary related to its function?

Answer 23

The thin walls allow for rapid diffusion of substances between the blood and cells. The small lumen means blood travels slowly for maximum diffusion opportunities and means they can fit between individual cells to provide substances all over the body.

Question 24

Which blood vessels supply the heart muscle with blood and oxygen?

Answer 24

The coronary arteries

Question 25

Outline the pathway that blood takes through the heart and lungs, starting with the vena cava.

Answer 25

Vena cava (deoxygenated), right atrium, tricuspid valve (atrioventricular), right ventricle, semilunar valve, pulmonary artery, lungs, pulmonary vein (oxygenated), left atrium, bicuspid valve (atrioventricular), right ventricle, semilunar valve, aorta, body.

Question 26

What are the three stages of the cardiac cycle?

Answer 26

Atrial systole, ventricular systole, diastole

Question 27

Describe what happens during atrial systole.

Answer 27

Atria contract, forcing blood down into the ventricles. Atrioventricular valves are open.

Question 28

Describe what happens during ventricular systole.

Answer 28

Ventricles contract, forcing blood up into the blood vessels. Atrioventricular valves are closed, semilunar valves are open.

Question 29

Describe what happens during diastole.

Answer 29

Atria and ventricles are relaxed, blood drains down into the heart to refill it. Atrioventricular valves are open, semilunar valves closed.

Question 30

Describe the formation of atherosclerosis.

Answer 30

Damage to the artery wall leads to inflammatory response and a build-up of cholesterol. The fatty deposits enlarge to form an atheroma. Calcium builds up around the atheroma, and hardens to form a plaque. This makes the artery less flexible and narrower.