neurons and synaptic transmissions Flashcards
what are neurons also know as ?
nerve cells
what are neurons?
body’s communication system
they are all over the body (80% in brain)
how do neurons communicate?
- communicates with 1000s of other cells in huge network pathways —> these adapt as experience new things and neurons are formed when we learn something new (plasticity)
what are the 3 types of neurons and order of them?
sensory —> relay —> motor
what’s a motor neuron?
- connects CNS to muscles and glands (effectors)= they can move e.g. contraction/relaxation of muscles
- short dendrites and long axon
what’s a relay neuron?
- in CNS and carry signals, connects neuron to neurons
- relays info
- short dendrites and axon
what’s a sensory neuron?
- sends information from PNS to CNS
- keep brain informed about external and internal environment info coming from sense organs
- long dendrites, short axon
synaptic transmissions- what are the parts involved?
synaptic cleft
vesicle
neurotransmitters receptor molecules
pre and post synaptic neuron
function of synaptic cleft, vesicles and neurotransmitter receptor molecules?
synaptic cleft - where electrical signals turned to chemical messengers (neurotransmitters) which can be detected by next neuron
vesicles- contains neurotransmitters
neurotransmitters receptor molecules- each neurotransmitter has its own specific molecular structure that fits to receptor
function of pre synaptic neuron and post synaptic neuron?
pre synaptic neuron- where action potential starts (an electrical impulse which is triggered for neurons to ‘fire’ and conduct signals to stimulate synaptic transmission. Always travels from main cell body down axon to synaptic terminals
post synaptic neuron- where message travels to
explain the 6 stages of synaptic transmission.
- pre synaptic neuron- electrical impulse (action potential) travels down axon to synaptic terminal
- vesicles release neurotransmitters, electrical impulse binds, becomes chemical and diffuses across synaptic gap
- neurotransmitters binds to receptors to post synaptic neuron
- if summation (overall charge of impulse) is positive then post synaptic neuron will fire (excitatory) and impulse continues
- if summation is negative= post synaptic neuron won’t fire (inhibitory)
- neurotransmitters then either get: broken down by enzymes in synapse/get reabsorbed by pre synaptic neuron ready for next impulse/diffuse away
what’s an excitatory neurotransmitter?
- make it more likely next neuron will fire
- stimulate an action potential in post synaptic neuron, increase neurons positive charge= makes it more likely to ‘fire’
- e.g. adrenaline
what’s an inhibitory neurotransmitter?
- inhibit an action potential in post synaptic neuron
- increase neurons negative charge= less likely to ‘fire’
- e.g. serotonin
neuron structure: myelin sheath axon, nodes of ranvier
myelin sheath= fatty deposits that coats axon, provides electrical insulation and speeds up action potential
axon= long arm of neuron- electrical impulse passes through it to communicate to other neurons
nodes of ranvier= gaps between myelin sheath that also speed action potential
neuron structure: schwann cell, dendrites, nucleus, cell body
schwann cell= type of glial cell that holds nerve cells in place and helps them work together and holds myelin sheath together
dendrites= receives info from other neurons and carries electrical charges from one neuron to next
nucleus= stores DNA for neuron
cell body= location of key components of cell r.g. nucleus, mitochondria
neuron structure: axon hillock, synapse, synaptic terminals
axon hillock= connects all body to axon where never impulses are generated from
synapse= small gap between pre and post synaptic neuron (where neurotransmitters are released)
synaptic terminals= end of axon where nerve impulse becomes a chemical message (neurotransmitters) which can be passed to other cells/neurons
