Transport in Animals
- Created by: Eleanor Izzard
- Created on: 13-12-12 09:46
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- Transport in Animals
- Surfaces for Exchange
- Special surfaces are needed because all living cells need certain substances to keep them alive
- Proteins - growth and repair
- Fats - make membranes, energy store
- Glucose - energy source
- Water - involved in lots of reactions
- Oxygen - aerobic respiration
- Minerals - maintain water potential, help enzyme action and metabolism
- all living cells must be able to remove waste products from metabolic activities : CO2, O2, other wastes like urea/ammonia (excess nitrogen)
- Organisms can absorb these substances from the surrounding environment or make them in their cytoplasm ( as part of cell metabolism)
- Single celld/small organisms can exchange gases/nutrients/ wastes via diffusion accross the outer surfaces
- they have a large surface area to volume ratio, so the process is quick enough for the cells to survive
- Multicellular/Large Organisms have small surface area to volume ratios and need more supplies to maintain life
- they are unable to get all that they need from diffusion on the outer surface as they would die before enough got to their inner cells
- they therefore require a transport system to move substances around the body quickly
- they are unable to get all that they need from diffusion on the outer surface as they would die before enough got to their inner cells
- Good Exchange Surfaces
- Large Surface area - more space for molecules to pass through
- fresh supply of molecules on one side - concentration gradient maintained
- thin barrier - reduce diffusion distance
- Removal of required molecules on one side to keep concentration low - maintain concentration gradient
- EXAMPLES
- Walls of alveoli in lungs
- Small intestine - nutrients absorbed
- root hairs of plants - water + minerals
- Special surfaces are needed because all living cells need certain substances to keep them alive
- Transport Systems
- Good features
- exchange surfaces to enable O2 and nutrients to enter blood and leave where needed
- a pump for pressure to push fluid around body - HEART
- A fluid/medium to carry nutrients/O2 around the body - BLOOD
- Tubes/Vessels to carry blood
- 2 curcuits - one to pick up O2 and one to deliver O2
- Needed if they are large, with a small surface area to volume ration and have a high level of activity
- SA:V ratio is affected by shape - long and thin vs short and fat. Thick is necessary for organisms to be large - for strength need bones/range of tissues
- SA:V ratio must be small as V increases whilst SA doesn't
- Level of Activity - if an animal is very active it requires a good supply or nutrients and oxygen to supply the energy for movement/warmth
- SA:V ratio is affected by shape - long and thin vs short and fat. Thick is necessary for organisms to be large - for strength need bones/range of tissues
- Single Circulatory
- Blood flows from the heart to the oxygen supply and then to the body and heart again.
- .E.G. Fish - heart, gills, body, heart
- In fish, the blood pressure is reduced as blood passes through tiny capillaries in the gills so it will not flow as quickly to the rest of the body - thus limiting the rate that oxygen/nutrients can be delivered to respiring tissues
- Blood flows from the heart to the oxygen supply and then to the body and heart again.
- Double Circulatory
- 2 separate curcuits - one takes blood to lungs to pick up O2 (pulmonary circulation) and other carries oxygen filled blood/nutrients around the body (systemis circulation)
- Mammels: heart, body, heart, lungs, heart
- the systemic circulation can carry blood at a higher pressure than the pulmonary circulation
- the heart can increase the pressure of the blood after it has been through the lungs so blood flows more quickly through the body tissues
- the blood pressure must not be too high in the pulmonary circulation or it could damage delicate capillaries
- Mammels - active animals and need to maintain their body temperature
- both the energy for activity and the heat are needed require energy from food
- An efficient circulatory system is needed to deliver O2 and nutrients quickly to the parts of the body where they are needed - the blood can be made to flow more quickly by increasing the blood pressure created by the heart
- Good features
- Surfaces for Exchange
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