Human circulatory system
- Created by: elen roberts
- Created on: 22-05-13 14:41
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- Human circulatory system
- Double circulatory system - first goes through the lungs, then the heart
- Liver - Hepatic Kidney - Renal
- Aorta -> Arteries -> Arterioles -> Capillaries -> Venules -> Veins -> Vena Cava
- Arteries
- Carry oxygenated blood around the body
- Small lumen
- Maintain high pressure
- Thick muscle
- To control and distribute blood flow
- Thick elastic
- Expand during systole and relax during distil to even the flow
- Capillaries
- Allow gass exchange
- One cell thick squamerous endothelium
- Short diffusion distance
- Thin, pourus walls
- Allows exchange of materials
- Very small lumen
- Veins
- Carry deoxygenated blood back to the heart
- Thin walls, mostly collagen
- Large lumen
- Reduces friction
- Many valves
- Prevents back-flow
- Body relies on constant contractions of muscles around veins to get the blood back to the heart
- Tissue fluid
- Arteriole end - high pressure gradient, substances are forced out
- RBC and plasma proteinsremain in blood as they are too large
- Venule end - water moves in by osmosis, larger WP due to tissue fluid and plasma in the blood, osmosis is slower, so tissue fluid forms
- Excess fluid is drained into lymphatic system
- Lymphatic system
- Runs alongside the veins, towards the heart
- Drain back into the blood system near the Vena Cava
- No pump, contains valves and helped along by contraction of muscles.
- Drain excess fluid, absorbs fat from small intestine and is part of the immune system
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