B4.2 The Blood Vessels

Question 1

What are the three main types of blood vessels?

Answer 1

Artery/ies
Vein/s
Capillary/ies

Question 2

Explain the function and adaptations of the arteries.

Answer 2

The arteries carry blood away from the heart to the organs. They have thick walls containing muscles and elastic fibres. Since the blood is under pressure, being pushed around the body, if an artery is cut, blood will spurt out rapidly every time the heart beats.

Question 3

Explain the function and adaptations of the veins.

Answer 3

The veins carry blood away from the organs towards the heart. They have much thinner walls than arteries, and often have valves to prevent the backflow of blood. This blood is squeezed back towards the heart by the action of the skeletal muscles, which relax and contract.

Question 4

Explain the function and adaptations of the capillaries.

Answer 4

The capillaries form a network of tiny vessels linking arteries and veins. They are narrow with very thin walls, allowing substances like oxygen and glucose to diffuse out of the blood easily. Substances produced by the cells pass easily into the blood through the walls of the capillaries.

Question 5

Explain the double circulatory system.

Answer 5

One transport system carries blood away from the heart to the lungs.
Another system carries blood from the heart to all other organs in the body and back again.
It is very efficient in warm-blooded animals as there is constantly oxygenated blood arriving from the lungs and being sent to the organs.