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