Circulatory System - Blood Vessels Flashcards
What do arteries do?
They carry blood away from the heart.
What do capillaries do?
They are involved in the exchange of materials at the tissues.
What do veins do?
They carry blood to the heart.
What are veins, capillaries and arteries all called?
Blood vessels.
Why are artery walls strong and elastic?
Because the heart pumps the blood out at a high pressure.
What is the hole in the middle of the artery?
The lumen.
Why do arteries contains thick layers of muscle and elastic fibres?
The thick layers of muscle are there to make them strong.
Elastic fibres are there to allow them to stretch and spring back.
What do arteries branch into?
Capillaries.
What is the size of capillaries?
They are tiny - so small you can’t see them
Where do capillaries carry blood to?
They carry blood very close to every cell in the body to exchange substances with them.
What is so good about the walls of a capillary?
They are permeable so substances can diffuse in and out. They are also one cell thick so it increases the rate of diffusion by decreasing the distance over which it occurs.
What do capillaries supply and take away?
They supply food and oxygen and take away waste like carbon dioxide.
What do capillaries join up to form?
Veins.
Why do veins have a bigger lumen than arteries?
To help the blood flow despite the lower pressure.
Why do veins have valves?
To keep the blood flowing in the right direction.
