Circulation

Circulation

1. The circulatory System

   • Carries nutrients and oxygen to cells
   • Removes Carbon dioxide from the cells
   • transports other waste products to where they can be disposed of
   • distributes heat around body
   • heart
     • Engine room of circulatory system, pumps continuously to keep the blood moving through vessels
   • blood vessels
     • Motorways, main roads and side streets along which blood flows
   • blood

2. Blood vessels

   • Arteries
     • carry blood away from the heart
     • when the heart beats, it pumps blood through arteries under pressure
       • the walls of the arteries must be tough and elastic to withstand this pressure
     • If an artery is cut, then high pressure within it causes blood to spurt out very quickly
       • Arteries are protected deep in your body
   • capillaries
     • extend through the body, arteries branch into smaller and smaller blood vessels. The finest of these are capillaries
     • Capillaries walls are only one cell thick, this allows dissolved material to pass through them
   • veins
     • Veins carry blood back to the heart
     • Blood is pushed back to the heart by the contractiion of muscles pushiing against the veins
     • To make sure blood moves in one direction, there are valves along the veins
       • Valves open when blood is flowing to the heart and close when blood is flowing away from it

3. Bruises

   • Bruises form when capillaries near the skin burst and the blood leaks into the surrounding tissue

4. Heart

   • It is the size of your fist and situated in the middle of your chest
     • The circulatory system is known as a double system because there are two separate circuits
       • In the first circuit: Flood flows from the heart to the body and back to the heart, this circuit carries oxygen and nutrients to the heart
       • In the second circuit, blood flows from the heart to the lungs and back again

5. Blood

   • The only organ in the body that exists as a liquid
   • In blood, there are red blood cells, white blood cells, plasma and platelets

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