2.82 Communication

Key Points:
1. Responses can be controlled by nervous or hormonal communication. In the example, the motor nerve is shown and one side is embedded in the spine and the other end is in the effector, probably the muscle.
2. The electrical impulse is carried down inside the nerve from the cell body to the structure called the synaptic knob -> connects to muscle. These cells can be up to a meter long.
3. The long structure is known as an axon. In mammals the axon is surrounded by a lot of fat in globules - this is to increase the speed on impulses.
4. The second way is known as endocrine system. This involves an endocrine gland and this produces a hormone. Manufactured in the glands, the adrenal glands. The hormone is secreted into the blood, the hormone being adreneline. This will arrive at the target tissue/organ.
5. Contrasting with the nerve system, some hormones can have multiple targets and bring about multiple effects.

Nerves = Fast, electrical impulse, single effect, reflex, carried down the axon.
Hormones = Relatively slow, can have multiple effects, secreted into blood.