Nervous System Flashcards
What does central nervous system consist
Brain + spinal cord (relay neurones)
What peripheral nervous system ?
All the nerve in the body (sensory and motor neurons)
Neurons
Nerve cell that transmit nerve signal to and fro the brain
Dendrites function
Branches that function as signal receivers
Cell body function
Spherical part of the neuron that contains the nucleus
Axon description
Long extension part which takes info away from the cell body
What is sensory neurons function (PNS)
Carry messages from the body sense receptors to the CNS
What is relay neurons (CNS)
Carry messages from one part of the CNS to another
What motor neurons (PNS)
Carry signals from the CNS to the muscles and glands
Sensory dendrites, axons and overall
Long
Short
Long
Relay dendrites, axons and overall
Short
Short
Short
Motor dendrites, axons and overall
Short
Long
Medium
Reflex action
Involuntary response to the stimulus
Fast to avoid the pain or cause harm
Reflex action
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)
Define synapse
Junction that neuron forms with another cell for communication
Function nervous
Nervous system - uses both electrical and chemical signals
The synapse process
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
