Mass transport in humans
- Created by: emma
- Created on: 17-04-14 16:11
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- Mass Transport
- Mass flow
- Bulk movement of liquid and gases due to a pressure difference
- Arteries
- Endothelial layer- one cell thick, reduce friction as smooth
- Elastic layer- Large amount of elastic to stretch and recoil as blood pulses through at high pressure, evens out pressure
- Muscle layer- contractions restrict vessel to reduce volume of blood passing through
- Arterioles
- Smaller vessels than arteries and connect arteries to capillaries
- Elastic layer is thinner as blood pressure lower and less need for elasticity as blood pulses through
- Muscle layer is thicker as contract to constrict vessel and reduce blood flow or relax and dilate vessel to allow more blood flow to the organ
- Veins
- Thin muscle layer- no need for vaso-constriction as blood going back to heart
- Valves- stop back flow of blood
- Thin muscle layer- no need for stretch and recoil as low blood pressure
- Capillaries
- Only endothelial layer- very thin, short diffusion distance
- Numerous and branched- increase surface area
- Narrow- ensures RBC always in contact with wall, reduce diffusion distance and increase surface area
- Tissue fluid
- At beggining of capillary high hydrostatic pressure forces water out
- Large proteins remain in capillary
- At end a capillary, low water potential in capillary due to plasma proteins
- Water enters capillary via osmosis
- 10% returns via the lymph system
- Water enters capillary via osmosis
- At end a capillary, low water potential in capillary due to plasma proteins
- Large proteins remain in capillary
- At beggining of capillary high hydrostatic pressure forces water out
- Mass flow
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