Nervous System

Brain + spinal cord (relay neurones)

All the nerve in the body (sensory and motor neurons)

Nerve cell that transmit nerve signal to and fro the brain

Branches that function as signal receivers

Spherical part of the neuron that contains the nucleus

Long extension part which takes info away from the cell body

Carry messages from the body sense receptors to the CNS

Carry messages from one part of the CNS to another

Carry signals from the CNS to the muscles and glands

Long Short Long

Short Short Short

Short Long Medium

Involuntary response to the stimulus Fast to avoid the pain or cause harm

Stimulus Pain receptor stimulated Signal sent along - sensory neuron Signal passed along relay neuron (message sent to brain) Signal sent along motor neuron Effector muscle contracts (response)

Junction that neuron forms with another cell for communication

Nervous system - uses both electrical and chemical signals

1) an electrical impulse travels along an axon (presynaptic neuron) 2) this triggers the nerve ending of a neuron to release chemical messengers called neurotransmitters 3) these chemical diffuse across the synaptic cleft and bind with receptor molecule on the membrane of the next neuron (postsynaptic neuron) 4) the receptor molecule on the postsynaptic neuron. This stimulates the postsynaptic neuron to transmit the electrical impulse