Mammalian Circulatory System

Question 1

What type of circulatory system does a mammal have?

Answer 1

Closed and double circulatory.

Question 1

What is meant by a closed circulatory system?

Answer 1

Blood remains within the blood vessels.

Question 2

What is meant by a double circulatory system?

Answer 2

Blood passes through the heart twice in each circuit. There is 1 circuit that delivers blood to the lungs and another which delivers blood to the rest of the body.

Question 3

What moves blood from the lungs to the heart?

Answer 3

Pulmonary vein

Question 4

What moves blood from the heart to the body?

Answer 4

Aorta

Question 5

What moves blood from the body to the heart?

Answer 5

Vena cava

Question 6

What moves blood from the heart to the lungs?

Answer 6

Pulmonary artery

Question 7

Which 2 blood vessels carry oxygenated blood?

Answer 7

Pulmonary vein and aorta

Question 8

Which 2 blood vessels carry deoxygenated blood?

Answer 8

Pulmonary artery and vena cava

Question 9

Why do mammals need the double circulatory system?

Answer 9

To manage the pressure of blood.

Question 10

How does blood flow through the lungs?

Answer 10

At lower pressures to prevent damage to the capillaries in the alveoli and reduce the speed which blood flows to enable more time for gas exchange.

Question 11

What happens to the blood after the lungs?

Answer 11

The oxygenated blood from the lungs goes back through the heart to be pumped out at a higher pressure to the rest of the body.

Question 12

Why does blood need to be pumped at high pressure to the rest of the body?

Answer 12

To ensure the blood reaches all the respiring cells in the body.

Question 13

What are the two blood vessels in the kidneys?

Answer 13

Renal artery and renal veins.

Question 14

How are the major blood vessels connected within the circulatory system?

Answer 14

Via the arteries, atrioles, capillaries and veins.

Question 15

Describe the walls of the heart.

Answer 15

Thick muscular layer called the cardiac muscle.

Question 16

Describe the properties of the cardiac muscle.

Answer 16

It is myogenic (it can contract/relax without nervous or hormonal stimulation).
It never fatigues (as long as it has a supply of oxygen).

Question 17

What do coronary arteries do?

Answer 17

Supply the cardiac muscle with oxygenated blood.

Question 18

Where are the coronary arteries?

Answer 18

On the surface of the heart, they branch off the aorta.

Question 19

What would happen if the coronary arteries became blocked?

Answer 19

The cardiac muscle wouldn’t receive enough oxygen and therefore wouldn’t respire and the cells would die. This results in a myocardial infarction.

Question 20

What is a myocardial infarction?

Answer 20

Heart attack.

Question 21

Describe the atria.

Answer 21

Thinner muscular walls. Don’t need to contract as hard as it is not pumping blood far (only to ventricles). It has elastic walls to stretch when blood enters.

Question 22

Describe the ventricles.

Answer 22

Thicker muscular walls. This creates a higher blood pressure to flow longer distances (to the lungs and the rest of the body). Ventricles pump blood around the body or to lungs.

Question 23

Describe the right ventricle.

Answer 23

Pumps blood to the lungs.

Question 24

Describe the left ventricle.

Answer 24

Pumps blood to the body. Thus it needs to be at a higher pressure to ensure blood reaches all the cells in the body. Thus it has thicker muscular walls compared to the right ventricle to enable larger contractions of the muscle to create higher pressure.

Question 25

What are the 2 major veins?

Answer 25

Vena cava and pulmonary vein.

Question 26

What do veins do?

Answer 26

Carry blood to the heart.

Question 27

What does the vena cava do?

Answer 27

Carries deoxygenated blood from the respiring body tissues to the right atrium.

Question 28

What does the pulmonary vein do?

Answer 28

Carries oxygenated blood from the lungs into the left atrium.

Question 29

What are the 2 major arteries?

Answer 29

Pulmonary artery and aorta.

Question 30

What does the pulmonary artery do?

Answer 30

Carries deoxygenated blood from the right ventricle to the lungs to become oxygenated.

Question 31

What does the aorta do?

Answer 31

Carries oxygenated blood from the left ventricle to the rest of the respiring body tissues.

Question 32

Where are semi lunar valves found?

Answer 32

In the aorta and pulmonary artery.

Question 33

Where are the atrioventricular valves found?

Answer 33

Between the atrium and the ventricles.

Question 34

What is the left atrioventricular valve also known as?

Answer 34

Bicupsid valves

Question 35

What is the right atrioventricular valve also known as?

Answer 35

Tricupside valves.

Question 36

What do valves do?

Answer 36

Prevent the backflow of blood.

Question 37

When do valves open?

Answer 37

When pressure is higher behind the valve.

Question 38

When do valves close?

Answer 38

When pressure is higher in front of the valve.

Question 39

What is the septum?

Answer 39

A piece of cardiac muscle that runs down the middle of the heart that separates the left and right side of the heart and the deoxygenated and oxygenated blood.

Question 40

Why is the septum important?

Answer 40

It maintains a high concentration of oxygen in oxygenated blood to maintain the concentration gradient to enable diffusion at respiring cells.

Question 41

Where does deoxygenated and oxygenated blood go?

Answer 41

Deoxygenated blood in the right side of heart is pumped to the lungs. The oxygenated blood in the left side of the heart is pumped to the rest of the body.

Question 42

What blood vessel enters the kidneys?

Answer 42

Renal arteries. They carry oxygenated blood from the heart to the kidneys.

Question 43

What blood vessels leaves the kidneys?

Answer 43

Renal veins. They carry deoxygenated blood to the vena cava from the kidneys.

Question 44

Suggest why the wall of the left ventricle is thicker than that of the right.

Answer 44

Thicker muscle to contract with greater force. To generate higher pressure to pump blood around the entire body.

Question 45

Explain how the structure of the arteries relates to their funcion.

Answer 45

- Narrow lumen - increases/maintains high pressure. - Smooth/folded endothelium - reduces friction/can stretch. - Thick wall - withstand high pressure/prevent bursting. - Thick elastic tissue - can stretch as ventricles contract and recoil as ventricles relax to maintain high pressure. - Thick smooth muscle tissue - can contract and control blood flow.

Question 46

What is the function of the arterioles?

Answer 46

Division of arteries to small vessels which can direct blood to different capillaries/tissues.

Question 47

Explain how the structure of the arterioles relates to their function.

Answer 47

Thicker smooth muscle layer in comparison to arteries: - Contracts - narrows lumen (vasoconstriction) - reduces blood flow to capillaries. - Relaxes - widens lumen (vasodilation) - increases blood flow to capillaries. Thinner elastic layer - pressure surges are lower.

Question 48

Explain how the structure of veins relates to their function.

Answer 48

Wider lumen than arteries - less resistance to blood flow. Very little elastic and muscle tissue - blood pressure is lower. Valves - prevent the backflow of blood

Question 49

Explain how the structure of capillaries relates to their function.

Answer 49

Wall is thin (one cell) layer of endothelial cells - reduces diffusion distance. Capillary bed is a large network of branched capillaries - increases surface area for diffusion. Narrow lumen - Reduces blood flow rate so more time for diffusion. Pores in walls between cells - allows larger substances through.

Question 50

What is the function of a capillary?

Answer 50

Allow efficient exchange of substances between blood and tissue fluid.