Blood Vessels
- Created by: Jasmin
- Created on: 06-05-13 11:52
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- Blood Vessels
- ARTERIES
- Carry blood away from the heart to the organs
- Carry blood under pressure
- Contain thick layers of muscle to make strong walls
- Elastic fibres allow walls to stretch and spring back
- Walls are thicker than lumen
- Blood is usually bright red and oxygenated
- VEINS
- Carry blood to the heart
- Capillaries eventually join up to form veins
- Blood is at lower pressure in veins so walls do not have to be as thick
- Bigger lumen to help blood flow despite low pressure
- Blood is low in oxygen - deep purperly - red colour
- Do not have a pulse
- Have valves to prevent the blood flowing in the wrong direction
- CAPILLARIES
- Form a huge network of tiny vessels linking arteries and veins
- Arteries branch into capillaries
- Really tiny
- Involved in exchange of materials at the tissues
- Really close to every cell
- Permeable walls so substances like glucose and oxygen can diffuse in and out
- Supply food and oxygen and take away waste like CO2
- Walls are only one cell thick. Increases rate of diffusion by decreasing distance over which it occurs
- ARTERIES
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