The Circulatory System - Blood Vessels Flashcards
What is the function of the arteries?
To carry blood away from the heart.
What is the function of the capillaries?
They exchange nutrients and oxygens with the tissues.
What is the function of the veins?
Carry the blood back to the heart.
True or False?
In the arteries, the blood will be at high pressure.
True
This is because the blood has just been pumped out of the ventricles.
How do the arteries adapt to high pressure?
They need to be strong and elastic, so they have a thick layer of muscle tissue to keep them strong, and a thick layer of elastic tissue so they can stretch and recoil.
This makes the wall of the artery quite thick compared to its lumen, which is the hole or space in the middle of the vessel.
Are the capillaries very small or very large?
They are very small.
What do the capillaries do with our cells?
Exchange substances
Giving them useful nutrients and oxygen and taking away waste products, like carbon dioxide.
How are capillaries adapted for their function?
Their walls are only a single cell thick. They are also permeable, meaning substances can easily diffuse through them. It doesn’t need to be super strong like an artery because blood flows much slower.
Which blood vessel has the largest lumen?
Veins
How are veins adapted for their function?
They have a large lumen, and a wall made up of only small layers of elastic fibres and smooth muscle. The blood they carry is at a very low pressure.
They also contain valves.
What are the function of valves?
They prevent blood from flowing backwards, ensuring that it always flows towards the heart.
How do you calculate the rate of blood flow?
The Rate of Blood Flow = Amount of Blood / Time
