Course Content
TRANSPORT IN PLANTS AND ANIMALS
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EXCRETION AND HOMEOSTASIS
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Biology Form 2
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Open circulatory system

The blood circulates in a general body cavity known as haemocoel.

The blood flowing through the haemocoel is also known as haemolymph.

The blood comes into direct contact with body tissues.

The blood lacks haemoglobin and hence does not transport oxygen; instead, it transports food nutrients and waste products.

This is common in arthropods.

 

Insect circulatory system

A typical insect like a cockroach has a haemocoel through which haemolymph flows in contact with body cells.

It has an open circulatory system composed of a tubular heart above the alimentary canal. The heart has thirteen chambers three of which are in the thoracic region and the remaining in the abdominal region. The anterior opening of the tubular heart is the aorta. The aorta empties the haemolymph into the haemocoel. The haemolymph bathes the body tissues. The tissues absorb useful substances from it and release waste products into it by diffusion.

 

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