(nervous system) structure & function of neurons Flashcards
neurons
cells within nervous system that conduct nerve impulses
3 types of neurons
- sensory
- relay
- motor
components of a neuron
- nucleus
- dendrite
- cell body
- myelin sheath
- node of ranvier
- axon
- terminal buttons
structure of cell body
includes nucleus which contains genetic material of cell
where are dendrites found & function
found: branches off cell body on neurons
function: carry nerve impulses from neighbouring neurons towards cell body
where’s the myelin sheath found & function
found: covers the axon & segmented by nodes of ranvier
function: protects axon & speeds up electrical transmission of impulse
function of nodes of ranvier
speed up transmission of impulse by forcing it to ‘jump’ across gaps along axon
function of axon
carries impulses away from cell body down length of neuron
what’s the axon
joins cell body & terminal buttons
function of terminal buttons
communicate with next neuron in chain across gap (synapse)
function of sensory neurons
- send info to brain regarding senses
- aka afferent neurons as carry info from PNS to CNS
- keep brain informed on internal/external environments
- only transmit messages
structure of sensory neurons
- long dendrites & (relatively) short axons
- cell body usually to side of cell
function of motor neurons
- carry signals from CNS towards organs, muscles & glands
- efferent neurons as carry info away from CNS towards PNS
- transmit & receive messages
- if connected to muscle = motor end plate
structure of motor neurons
- short dendrites & (relatively) long axons
function of relay neurons
- aka interneurons (take on role of sensory & motor neurons)
- connect sensory neurons to motor neurons
- based in CNS & carry signals/messages
- transmit/receive messages
structure of relay neurons
- short axons & short dendrites
location of motor neurons
- cell bodies may be in CNS
- long axons which form part of PNS
location of relay neurons
- make up 97% of all neurons
- found in brain & visual system
location of sensory neurons
- outside of CNS
- in PNS in clusters = ganglia
describe process of electrical transmission (firing of a neuron)
- in resting state, inside of cell is negatively charged compared to outside
- when activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur
- creates electrical impulse which travels down axon towards end of neuron
