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3.2 TRANSPORT IN ANIMALS - Coggle Diagram
3.2 TRANSPORT IN ANIMALS
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3.2.2 Blood vessels
Some animals, including insects, have an open circulatory system meaning blood is not held within blood vessels
(in insects) Blood from the heart through pores called ostia and the heart then pumps the blood towards the head via peristalsis
Disadvantages of open circulatory systems:
- low blood pressure and slow blood flow
- circulation may be affected by body movements
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Advantages of closed circulatory systems:
- Higher pressure meaning faster blood flow
- More rapid delivery of oxygen and nutrients
- More rapid removal of waste
- Transport independent of movements
Structure of the arteries...
- Small lumen
- Inner wall (tunica intima) consisting of a thin layer of elastic tissue
- Middle wall (tunica media) consisting a thick layer of smooth muscle
- Outer wall (tunica adventitia) consisting of a thick layer of collagen and elastic tissue
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Structure of the capillaries...
- Narrow lumen
- Walls consisting of a single layer of flattened endothelial cell
- Leaky walls
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Structure of veins...
- Large lumen
- Valves to prevent backflow
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