The CNS consists of the brain and spinal cord.

The PNS consists of all the neurones in nerves that connect the CNS to the rest of the body.

These include the neurones in spinal nerves and in cranial nerves.

1. Somatic nervous system - controlled consciously, sometimes called the voluntary nervous system
2. Autonomic nervous system - controlled subconsciously, sometimes called the involuntary nervous system

1. Sympathetic nervous system
2. Parasympathetic nervous system

The neurotransmitters for the sympathetic nervous system are adrenaline and noradrenaline.

The main neurotransmitter for the parasympathetic nervous system is acetylcholine.

The two largest divisions of the mammalian nervous system are the central nervous system (CNS) and the peripheral nervous system (PNS).

The sympathetic nervous system stimulates effectors, generally increases activity, and helps us cope with stressful situations by heightening our awareness and preparing us for activity.

It tends to be involved in 'fight or flight' responses.

The parasympathetic nervous system typically inhibits effectors, generally decreases activity, and controls activities under normal resting conditions.

It is concerned with conserving energy and replenishing the body's reserves.