Applied Lifecare - The Cardiovascular System

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   atria      away from      back to      clots      coronary      disease      high      low      oxygen      red      temperature      thick      thin      thinner      valves      ventricles      water      yellow   
Blood
You have between 5 and 7 litres of blood in your body.
It carries oxygen, carbon dioxide, urea and nutrients around your body. Blood also contains hormones, and it helps to regulate the body's and content.
Blood is made up of 4 main components.
1. Plasma - this is a pale liquid that contains hormones, nutrients and proteins.
2. Red blood cells - these contain the pigment haemoglobin which carries . Their special shape means they have a large surface area, and they have no nucleus - both these adaptations mean they are well suited for their job.
3. White blood cells - there are several different shapes of these. They fight against .
4. Platelets - these are small fragments of cells, and they stick together to make blood to stop bleeding after an injury.

Blood Vessels
1. Arteries - these carry blood the heart. They have muscular walls as the blood is at pressure. They divide into smaller vessels called capillaries.
2. Capillaries - these spread through the tissues to take blood to all the cells. They have very walls which allows plasma to leak out. Capillaries join up into veins.
3. Veins - these carry blood the heart. They have walls and are wider than arteries. Inside them, blood pressure is and the blood flows slowly. They have special which only allow the blood to flow in one direction.

Heart
The heart has four chambers. The top two are called . The bottom two are called . The heart has its own blood supply carried by the arteries. If this supply is blocked, a heart attack occurs.