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structure/function of neurons - Coggle Diagram
structure/function of neurons
motor
short dendrites long axons
connect CNS to effectors such as muscles and glands
carry information FROM the brain TO muscles and glands
sensory
long dendrites short axons
carry messages from the PNS to the CNS
carry information from sense organs TOWARDS brain
receptors found in eyes, ears, tongue, skin
relay
short dendrites short axons, no myelin sheath
connect sensory neurons to the motor or other relay neurone
carry information TO AND FROM the brain
involved in analysing information from neurons and deciding how to respond
found in brain/visual system/spinal cord
reflex arc
allows a quick response to a dangerous situation
function
provide nervous system with primary means of communication
transmit signals electrically and chemically
structure
consist of cell body, dendrites and axons
dendrites at one end of the neutron receive signals from other neurons or sensory receptors. dendrites are connected to the cell body, the control centre of the neuron. from the cell body the impulse is carried along the axon, where it terminates at the axon terminal
synaptic transmission
neurotransmitters
chemical messengers within the brain
role to transmit information from one neuron to another so person performs an action
synapse
gap between two neuron endings (dendrites) that allows neurotransmitters to diffuse across to carry on a message
process
1) electrical impulse (action potential) reaches the presynaptic terminal
2) causes vesicles in the presynaptic neuron to fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft
3) neurotransmitters cross the synaptic cleft
4) neurotransmitters combine with receptors on the postsynaptic membrane
5) neurotransmitters will cause a stimulation of postsynaptic receptors either: excitory effect or inhibitory effect
action potential
an explosion of electrical activity
occurs when a neuron sends information down an axon, away from the cell body
excitation or inhibition
excitatory neurotransmitter
chemical messenger that makes it more likely the next neuron will fire so an impulse will travel down its axon
increases brain activity in CNS
noradrenaline
inhibitory neurotransmitter
chemical messenger that prevents or reduces the likelihood the next neuron will fire
decreases brain activity in CNS
GABA
summation
when two neurons synapse at the same post synaptic neuron
summation occurs when the excretory and inhibitory influences are added together
if overall effect is mainly inhibitory it reduces the likelihood the neuron will fire an impulse down next neuron
if mainly excitory impulse will fire an impulse down the next neuron
neurons can only transmit information in one direction at the synapse because
receptors for neurotransmitters only present on postsynaptic membrane
is the binding of the neurotransmitter to receptors which enables info to be passed to next neuron
synaptic vesicles containing neurotransmitter only released from presynaptic membrane