3.2.2- Blood Vessels

Question 1

Define what the open circulatory system is.

Answer 1

One in which the blood is not held in vessels.

Question 2

In what type f animal is an open circulatory system often found?

Answer 2

Insects.

Question 3

Explain how blood transports around an animal with an open circulatory system.

Answer 3

The blood fluid circulates through the body cavity- the tissues are coated directly in blood.

Question 4

Explain the three different ways in which blood can be circulated around the body in an organism with an open circulatory system.

Answer 4

• Bodily movements help to circulate the blood.
• open ended tubes attached to the hear direct blood to active parts of the body
• heart like pumping tube lies under dorsal (upper) surface of the body. Blood enters the heart through Ostia (pores) and heart pumps blood to head by peristalsis. At top end of heart, blood pours out of the body cavity.

Question 5

Explain two disadvantages of the open circulatory system.

Answer 5

The blood is carried at low pressure- meaning there’s a slow blood flow. Circulation of blood may be controlled by bodily movements.

Question 6

Explain what the closed circulatory system is.

Answer 6

One in which the blood is held in vessels.

Question 7

In the closed circulatory system, what is it that bathes the tissues and cells?

Answer 7

Tissue fluid.

Question 8

Explain three advantages of the closed circulatory system over the open one.

Answer 8

• higher blood pressure so blood flows quicker.
• more rapid delivery of O2 and nutrients and removal of waste like CO2 and Urea.
• Transport is independent of bodily movements.

Question 9

All blood vessels have what in their walls?

Answer 9

A think later of lining tissue, made of a single layer of cells called the endothelium.

Question 10

There is a thin, single celled layer of lining tissue called _________ in the walls of every blood vessel.

Answer 10

Endothelium.

Question 11

Why is the endothelium that lines all blood vessels smooth?

Answer 11

So that it reduces friction with the flowing blood.

Question 12

What is an artery?

Answer 12

Vessels that carry blood away from the heart at high pressure.

Question 13

Why must the artery walls be particularly thick?

Answer 13

To withstand the high pressure created as the blood flows quickly and at high blood pressure.

Question 14

How is the high pressure maintained in the arteries?

Answer 14

It has a relatively small lumen to maintain the higher pressure. The outer layer of the artery is made of collagen and elastic tissue that recoils to maintain the pressure also.

Question 15

The inner walls of the arteries are folded so that…

Answer 15

The lumen can expand as the blood flow increases.

Question 16

Explain the three types of walls in the arteries, what their function is and what they’re made of.

Answer 16

• inner layer is a thin elastic tissue layer that allows the wall to stretch and recoil to help maintain BP.
• middle layer- thick smooth muscle
• outer layer- thick collagen and elastic tissue later. Provides strength to withstand high BP and recoils to maintain the pressure.

Question 17

What are the five typed is blood vessel within the mammalian body?

Answer 17

Arteries
Arteriolar
Capillaries
Venues
Veins

Question 18

What are the arterioles?

Answer 18

Small blood vessels that distribute blood from an artery to the capillaries?

Question 19

What is in the walls of the arterioles?

Answer 19

A thin layer of smooth muscle as well as the endothelium later.

Question 20

Explain the function of the smooth muscle in the walls of arterioles and why they may need to do this.

Answer 20

It contracts to constrict the lumens diameter to increase resistance to flow and reduce the rate of flow. This may be fine to divert the flow of blood to regions of the body that need more oxygen

Question 21

What are capillaries?

Answer 21

Blood vessels with very thin, leaky walls that allow the exchange of materials between blood and tissue fluid.

Question 22

Why are the walls of capillaries only made of one cell thick endothelial cells?

Answer 22

To reduce the diffusion distance of materials between the capillaries for faster and more efficient exchange.

Question 23

The walls of capillaries are leaky, meaning what?

Answer 23

They allow the blood plasma and dissolved substances to leave the blood.

Question 24

Explain why the lumen of capillaries are very small (7micrometers)- similar to the size of a red blood cell.

Answer 24

To squeeze the Rbc’s to the wall of the capillary as they pass through it. This will help with the transfer of oxygen as there will be a reduced diffusion path and resistance is increased to reduce the rate of flow.

Question 25

explain what venules are.

Answer 25

Small blood vessels that collect blood from the capillaries and take them to veins.

Question 26

What is the wall of venules made of?

Answer 26

Thin muscle and elastic tissue layers outside of the endothelium layer. Also a thin layer of collagen's present.

Question 27

What are veins?

Answer 27

Blood vessels that carry blood back to the heart at low pressure.

Question 28

Veins have a _______ lumen.

Answer 28

Large.

Question 29

Why are the walls of veins able to be thin?

Answer 29

Blood is carried at low pressure within the veins so the walls don't need to be thick.

Question 30

Why do veins have large lumen?

Answer 30

So that the flow of blood is eased.

Question 31

Explain what the walls of veins are comprised of.

Answer 31

Thin layers of collagen, smooth muscle and elastic tissue (thinner than in artery's).

Question 32

Veins contain _______ to help the blood flow back to the heart and prevent it flowing in the opposite direction.

Answer 32

VALVES.

Question 33

Explain how veins can be flattened and what this will cause and why.

Answer 33

They can be flattened by the action of the surrounding skeletal muscle. Contraction of the surrounding skeletal muscle will apply pressure to the blood and force blood to move along the veins in the direction determined by valves.