Topic 1 - Transport around the Body
- Created by: James Till
- Created on: 06-03-13 17:28
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- Transport around the body
- Transport in simple organisms
- One of the main ways molecules move in and out of a cell is by diffusion
- Diffusion is the movement of molecules down a concentration gradient from an area of high concentration to an area of low concentration
- For unicellular organisms, such as amoeba, nutrients and oxygen can diffuse directly into the cell and waste substances can diffuse directly out
- Transport in large organisms
- Substances have to travel longer distances to reach every cell in the body and they also can't move into the cells fast enough via simple diffusion to sustain life.
- Therefore, they have evolved specialized systems to get them into and around their bodies
- In humans, this is the heart and circulatory system and the blood that flows through it
- This is an example of a mass transport system - when substances are transported in the flow of fluid with a mechanism for moving it around the body
- In humans, this is the heart and circulatory system and the blood that flows through it
- Therefore, they have evolved specialized systems to get them into and around their bodies
- Substances have to travel longer distances to reach every cell in the body and they also can't move into the cells fast enough via simple diffusion to sustain life.
- Features of mass transport systems
- They have a system of vessels that carry substances - these are usually tubes that carry it via a specific course
- They have a way of making sure that substances move the correct way (i.e. nutrients in and waste out)
- They have a means of moving the substances around the body fast enough to meet the needs of the organism (i.e. the pumping of the heart)
- Transport in simple organisms
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