transport in the body 2

what are blood vessels

there are three main types of blood vessels

arteries

carry blood away from the body

As a result of carrying blood away from the heart, there is a strong flow of blood in arteries. we say that the blood in arteries is under high pressure

veins

Veins carry blood to the heart. the blood flow or pressure in the veins is low

capillaries

tiny blood vessels, they are between arteries and veins

walls are very thin. this allows material to pass into and out of capillaries.

the heart

the heart is the size of a clenched fist and located between the middle and the left hand side of the chest

the heart is made of a special type of muscle called cardiac muscle. cardiac muscle is very strong and does not tire easily

the heart contracts in order to pump blood around our body in blood vessels. the force of this blood causes a pulse

structure of the heart

chambers

the heart contains 4 chambers. the top two are the right and left atrium and the bottom two are the right and left ventricle

septum

the two sides of the heart are separated by a muscular wall called the septum

heart valves

valves in the heart make sure that the blood can flow only in one direction. in this way, they are simuilar to valves in a car tyre or football

the ventricles of the heart

the right ventricle pumps blood from the heart to the lungs. this is a reasonable short distance and so the muscular walls of the right ventricle are fairly thin

the left ventricle pumps blood from the heart all around the body. this is very long distance and so the muscular wall of the left ventricle are very thick

pulmonary artery and vein

Most of the arteries in the body carry oxygen-rich blood. however, the pulmonary artery is an exception to this rule as it carries blood low in oxygen

most of the veins in the body carry blood low in oxygen. however, the pulmonary vein is an exception to this rule as it carries oxygen-rich blood

The two blood circuits

in the lung circuit blood flows from the heart to the lungs and back to the heart

in the longer body circuit, blood flows from the heart to the rest of the body and back to the heart again

pulse

when blood is pumped through the arteries it causes a wave of pressure. this wave of pressure is called a pulse

a pulse can be felt in areas of the body where the arteries are close to the surface for example at the wrist and in the neck

average = 70 beats per min

exercise increases the pulse rate