Structure & Function of Circulatory System

Question 1

What are arteries?

Answer 1

A blood vessel that carries blood away from the heart

Question 2

Under what pressure does blood move in an artery?

Answer 2

Deoxygenated blood moves under high pressure.

Question 3

Describe the structure of the artery wall

Answer 3

The walls of an artery contain smooth muscle and elastic fibres.

Question 4

What does the structure of the artery wall allow it to do?

Answer 4

The walls of an artery can stretch to accommodate the extra blood when ventricles contract.

When they relax, the elastic walls recoil, allowing the blood to flow under high pressure.

Question 5

Describe the structure of the arterioles

Answer 5

The arterioles in large arteries contain smooth muscle important for regulating blood frow through the capillaries

Question 6

Describe the lumen found in arteries?

Answer 6

The smooth microscopic lumen allows for efficient blood flow.

Question 7

What are capillaries?

Answer 7

The link between the arteries and veins

Question 8

Describe the structure of a capillary

Answer 8

They are microscopic blood vessels that form a network to carry blood to nearly every cell, enabling cells to get requirements from the blood and pass waste into the blood

Question 9

Describe the structure of the capillary wall

Answer 9

The walls of capillaries are only one cells thick

Question 10

What does the structure of the capillary wall allow it to do?

Answer 10

Allows diffusion, movement and transport of substances to and from the plasma

Question 11

What are veins?

Answer 11

Carry blood towards the heart

Question 12

Describe the structure of veins

Answer 12

Veins are made up of capillaries that joint into small veins known as venules, which join to make larger veins

Question 13

Under what pressure is blood carried in veins?

Answer 13

Veins carry de/oxygenated blood to the heart at a low pressure, so the lumen is large

Question 14

Compare the structure of veins to arteries

Answer 14

Veins are less muscular compared to arteries with less elastic fibres.

Question 15

Why are veins less muscular compared to arteries?

Answer 15

This is because the blood pressure is relatively low because the blood losses most pressure as it flows through the capillaries.

Question 16

Why do veins have valves?

Answer 16

The pressure is constant, so the walls aren’t elastic.

Because of this pressure, veins have valves that prevent the backflow of blood.

Question 17

What is the heart?

Answer 17

The heart is the pump that pushes the blood around the body.

Question 18

Where is the heart located?

Answer 18

It is located between the two lungs in the mediastinum, behind and slightly to the left of the sternum.

Question 19

Describe the size of the heart

Answer 19

The heart is a conical shape approx. 12cm long, 9cm at its widest point and 6cm thick, making it about the size of an adult human fist

Question 20

What is the pericardium?

Answer 20

A membrane that completely encloses the heart, holds it in place but also allows the heart to move as it beats and prevents overstretching

Question 21

Describe the structure of the heart wall

Answer 21

The wall of the heart itself is made up of a cardiac muscle

Question 22

What is the septum?

Answer 22

A muscle that separates the left and right sides of the heart.

Question 23

What is the function of the right side of the heart?

Answer 23

The ride side of the heart collects blood from the body and pumps it to the lungs

Question 24

What is the function of the left side of the heart?

Answer 24

The left side receives blood from the lungs and pumps it to the rest of the body.

Question 25

What side of the heart forms the pulmonary circuit?

Answer 25

The right side of the heart forms the pulmonary circuit, from the lungs and back.

Question 26

Describe what happens at the pulmonary circuit

Answer 26

It carries deoxygenated blood from the heart to the lungs. Blood picks up oxygen from the air and releases carbon dioxide to the air. Oxygenated blood returns to the heart to be pumped around the body.

Question 27

What side of the heart forms the systemic circuit?

Answer 27

The left side of the heart forms the systemic circuit, from the heart to the body and back

Question 28

Describe what happens at the systemic circuit

Answer 28

It carries oxygenated blood from the heart to the rest of the body. Blood releases oxygen to the cells and picks up carbon dioxide from the cells. Deoxygenated blood returns to the heart to be pumped to the lungs.

Question 29

Where are the atrioventricular valves located?

Answer 29

Between the atria and the ventricles there is a flap of thin tissue with the edges held by tendons called chordae tendineae which attach to the heart on papillary muscles.

Question 30

What happens to the atrioventricular when the ventricles contract?

Answer 30

Blood catches behind the flaps and they billow out like a parachute, sealing off the opening between the atria and ventricles. Blood leaves through the arteries and doesn’t flow back into the atria

Question 31

Where are the semilunar valves located?

Answer 31

When the arteries leave the heart is a second set of valves that stop blood from flowing back into the ventricles when the ventricles relax known as the semilunar valves.

Question 32

Describe the structure of the semilunar valves?

Answer 32

It has three cusps.

Question 33

What happens to the valves when blood flows into the artery?

Answer 33

When blood flows into the artery, the cusps are pressed flat against the artery wall.

Question 34

What happens to the valves when blood flows back into the ventricles?

Answer 34

When blood tries to flow back into the ventricles, the cusps fill out and seal off the artery, ensuring that blood only flows in one direction.

Question 35

Where does the "lub dub" sound come from?

Answer 35

The “lub dub” sound comes from the closing of the atrioventricular and then the semilunar laves.