Neurons & synaptic transmission Flashcards
What is a neuron?
nerve cells that transfer information throughout the body (electrically & chemically)
Function of sensory neuron (afferent)
-located in the PNS
-Carry sensory information from PNS to the CNS
-long dendrites, short axons
Function of relay neuron (interneurons)
-located in the CNS(within brain)
-connect the sensory neuron to the motor neurons
-based in the CNS
-short axons, short dendrites
Function of motor neuron (efferent)
-located in the CNS
-Carry impulses from CNS towards effectors e.g. muscles/ glands
-short dendrites, long axons
function of dendrites
- branch-like structures
- carry nerve impulses from other neurons towards cell body
function of axon
-long slender structure
-carries nerve impulses (action potential) away from cell body towards axon terminal
- surrounded by myelin sheath which speeds up electrical transmission
function of axon terminal (buttons)
-Connects neurons to other neurons via synaptic transmission
Function of cell body(soma)
-contains nucleus with ‘genetic material’ of cell
Function of nodes of Ranvier
- gaps in myelin sheath
-re-charges action potential to help impulses travel faster
What are neurotransmitters?
chemical messengers, located in the synaptic vesicles of a neuron
What happens in the reflex arc?
- sense organs in PNS detects a stimulus e.g. change in temp
- sensory neuron sends the electrical impulse from PNS to relay neuron in brain/CNS
- Relay neurons connect sensory neurons to motor neurons (involved in analysis of sensations, what it means, how to respond etc)
4.Motor neurons send electrical impulses to an effector - effector produces a response e.g. muscle contracts
Firing of a neuron
neuron in resting state = cell negatively charged
activated by stimulus= cell positively charged = causing an action potential to occur
» electrical impulse travels down axon
Process of synaptic transmission
- electrical impulse arrives at the end of presynaptic neuron to the terminal buttons
- triggers release of neurotransmitters from synaptic vesicles of presynaptic neuron into the synapse
- neurotransmitters diffuse chemically across the synapse and bind to receptor sites on postsynaptic neuron
(any not picked up are broken down or reabsorbed through process of reuptake)
4.impulse converted back into electrical impulse
Role of inhibitory neurotransmitters
- Serotonin, GABA
-increases negative charge of postsynaptic neuron
-postsynaptic neuron is less likely to fire an impulse
Role of Excitatory neurotransmitters
- Adrenaline, dopamine
-increases positive charge in postsynaptic neuron
-postsynaptic neuron is more likely to fire an impulse