The body system responsible for carrying blood, nutrients, and waste throughout the body
Related to the heart
The structure of an artery, a vein and a capillary
Related to the lungs
This is known as the pulse.
In some places in the body the arteries are relatively near the surface.
In these places you can feel the bulge as blood is forced out of the heart into the arteries followed by the return to normal shape.
Diagram of pulse points on the body
Valves prevent a backflow of blood in the veins
It is in the capillaries that the exchange of substances takes place between the blood and the cells. The capillaries provide a massive surface area and thin walls for easy diffusion.
Dissolved food and oxygen move out of the blood into the cells down a concentration gradient by diffusion. Carbon dioxide and urea move out of the cells into the blood in the same way.
Blood moves from the arteries into the capillary network and then into the veins
The blood pumped out of the heart is carried around the body in a 75000 mile long transport network of blood vessels. There are three main types of blood vessels
the arteries, the veins and the capillaries.
Arteries and veins of the body
- carry blood away from the heart
- in most arteries blood is bright red and oxygenated
- stretch as the blood is forced through them and go back into shape afterwards (have a pulse)
- have thick walls to withstand the pressure of the blood
- carry blood towards the heart
- in most veins the blood is deep purple red and deoxygenated
- no pulse
- often have valves to prevent backflow of blood
- much thinner walls as much lower pressure
- huge network of tiny vessels linking arteries with veins
- narrow - often one red blood cell wide
- very thin walls one cell thick to allow diffusion of substances into and out of the blood
The main artery of the systemic circuit is
the aorta which branches out into other arteries, carrying blood to different parts of the body.