Arteries, Veins and Capillaries
Arteries transports oxygen rich blood away
from the heart to the body. Arteries have
thick elastic muscular walls. The fibres in the
walls of arteries can contract and relax to
control the diameter of the artery and thus
the follow rate of blood. Elastic fibres in the
walls expand and recoil with each heartbeat,
maintaining blood flow under high pressure.
Your pulse is a result of this rhythmic pattern.
Capillaries carry blood between arteries and
veins. Capillaries are only one cell thick and
surround all tissue cells. The very large
surface area of capillaries allows for the
exchange of oxygen, nutrients and waste
products between blood and body cells.
Veins return deoxygenated blood to the
heart. The wall of veins are thinner than
those in arteries, with less muscle and a
wider diameter; resulting in the blood being
transported under low pressure. To keep the
blood pulsing along, the veins have a series of
valves which prevent the blood from backflowing on its way back up to the heart.
Complete the table to compare the structure of arteries, capillaries and veins in relation to their function.
Arteries
Function
Structure
How
structure fits
function
Capillaries
Veins
Carry oxygenated blood away
from the heart
One cell think walls with very
large surface area.
No need for strong muscular
walls, as most of the blood
pressure has been lost.
Valves prevent back-flow of
blood under low pressure.