Blood Vessels

Question 1

How is blood transported in a closed blood circulatory system?

Answer 1

In a continuous system of tubes

These tubes are called the blood vessels

Question 2

How much blood circulates in the blood vessels? (On average)

Answer 2

5 litres

Question 3

What are the three main types of blood vessels?

Answer 3

Arteries
Capillaries
Veins

Question 4

What does an artery do?

Answer 4

Transport blood away from the heart

Question 5

How many layers do the walls of arteries consist of?

Answer 5

Three

Question 6

What are the three layers in artery walls?

Answer 6

Outer
Middle
Inner

Question 7

What is the outer layer of artery walls like?

Answer 7

Fibrous connective tissue

Question 8

What is the middle layer of artery walls like?

Answer 8

Smooth muscle tissue and elastic fibres

Question 9

What is another name for the inner layer of artery walls?

Answer 9

Endothelium

Question 10

What is the endothelium made of?

Answer 10

Squamous epithelium

Question 11

What does the muscle layer in an artery wall do?

Answer 11

Allows the artery to stretch when blood under high pressure is pumped from the heart into the artery
It helps to resist the high pressure and avoid distortion
The elastic fibres also help with this

Question 12

What is a lumen?

Answer 12

The inner space of a tube-shaped structure

Question 13

What is the shape of the lumen of an artery like?

Answer 13

More regular and smaller than that of a vein

Question 14

What do arteries do as they get further away from the heart?

Answer 14

They branch and become smaller and smaller

The outer two layers become thinner

Question 15

What are arterioles?

Answer 15

These smaller, branched arteries

Question 16

Do arteries have valves?

Answer 16

Apart from the pulmonary artery and the aorta, no

Question 17

Why don’t arteries have valves?

Answer 17

Because of the high pressure present in arteries

Question 18

What are capillaries?

Answer 18

Arterioles that have become microscopically small tubes

Question 19

Where do capillaries occur?

Answer 19

As a branched network between cells in the tissue

Question 20

What do the walls of capillaries consist of?

Answer 20

A single thin layer of endothelium

Question 21

What do capillaries do?

Answer 21

Allow for gaseous exchange between blood and cells to happen

Question 22

How large is the lumen of a capillary?

Answer 22

So small that red blood corpuscles can only move through in single file

Question 23

Why is it useful for red blood corpuscles to move through capillaries in single file?

Answer 23

This slows the blood flow so that the exchange of gases into and out of cells can take place more effectively

Question 24

What do capillaries do as they move away from the arterioles?

Answer 24

They reunite

Question 25

What are venules?

Answer 25

The blood vessels formed from reunited capillaries

Question 26

What are veins?

Answer 26

Blood vessels formed from united venules

Question 27

What do veins do?

Answer 27

Transport blood back to the heart

Question 28

What do vein walls consist of?

Answer 28

The same three layers as artery walls

Question 29

How do vein walls differ from artery walls?

Answer 29

The outer two layers are thinner

Question 30

What is the lumen of a vein like?

Answer 30

Larger and more irregular than that of an artery

Question 31

What is the pressure under which the blood in veins flows?

Answer 31

Low

Question 32

Why are the walls of veins thinner than those of arteries?

Answer 32

They do not need to withstand as much pressure

Question 33

How does blood flow through veins?

Answer 33

The contraction of skeletal muscles close to the veins helps the blood to move in the direction of the heart

Question 34

Do veins have valves?

Answer 34

Apart from the pulmonary veins, yes

Question 35

Why do veins need valves?

Answer 35

Blood travels up from the legs to the heart
This goes against gravity
Gravity pulls the blood back down
The valves stop this backflow

Question 36

What kinds of valves exist in the valves?

Answer 36

Semilunar valves