10.1 Co-ordination

Hormonal System

Nervous System

Communication via chemical hormones

Communication via nerve impulses

Transmitted in the blood

Transmitted through neurones

Transmission is slow

Transmission is quick

The hormones involved travel all over the body but only the targeted organs react

The impulse only reaches specific parts of the body

Response is widespread

Response is localised

Response is slow and long lasting

Response is quick and short term

Effect may be permanent and irreversible

Effect is temporary and may be reversible

• Chemical Mediators

Histamines: They are stored in white blood cells and are released in response to an allergen or an injury. They cause dilation of small arteries and arterioles and they increase the permiability of capillaries. This has the…