B2 - The Circulatory System
- Created by: Friesia
- Created on: 26-10-15 10:53
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- B2 - The circulatory system
- Oxygen and nutrients are carried in blood to the body cells
- Waste substances, eg. CO2 are carried away from the cells
- The heart has a double pump
- the right side pumps de-oxygenated blood to the lungs to collect oxygen and remove carbon dioxide
- The left side pumps oxygenated blood around the body
- There are three major types of blood vessel
- Arteries
- carry blood away from the heart to the body cells
- comes out of the heart at high pressure
- so the artery walls have to be strong and elastic
- thicker than veins
- so the artery walls have to be strong and elastic
- Veins
- carry blood back to the heart
- Blood is at lower pressure so the walls dont have to be as thick
- Have a bigger lumen to help the blood flow through more easily
- Have valves to help blood flow in the right direction
- Capillaries
- branches of arteries that are really tiny
- carry the blood really close to each individual cell in the body to exchange substances with them
- permeable walls so substances can diffuse in and out
- supply nutrients and oxygen and take away wastes like CO2.
- walls are only one cell thick
- increases the rate of diffusion
- Arteries
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