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Why do organisms have a transport system:

Features of Transport Systems:

Diffusion is fast enough for transport over short •
distances
...

Specialist exchange surfaces are required to absorb nutrients and excretory products
...
A transport system is required
to take materials from cells to exchange surfac•
es and from exchange surfaces to cells
...


A suitable medium in which to carry materials (like
blood)
...


A form of mass transport in which the transport
medium is moved around in bulk over large distances = more rapid diffusion
...


As organisms have evolved into larger and more
•
A mechanism for moving the transport medium
complex structures, the tissues and organs of
within vessels
...

ised and dependant upon one another
...

body muscles or of a specialised pumping organ,
need for a specialised transport system with a
such as the heart
...


Circulatory system
of a mammal

2
...


•

A mechanism for the mass flow of water or gases
(like the diaphragm and intercostal muscles
...

This is because when blood is passed through the lungs, its
pressure is reduced
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Blood is therefore returned to the heart to boost its pressure before being circulated to the rest of the tissues
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The vessels that make up the circulatory system of a mammal are divided into three types: arteries, veins and capillaries
...
The final exchange from blood vessels into cells is
rapid because it takes place over a large surface area,
across short distances and there is a steep diffusion gradient

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