Neurones Flashcards
Describe parcinien corpuscle
Has stretch mediated sodium channels
- Pressure applied channels open, Na+ diffuse = generator potential
Action potential
At rest (-60mV) 3Na+ out for every 2K+ in
Some Na+ channels open causing more to open
-When generator potential surpasses threshold potential
-Membrane depolarises beyond threshold value of -50m
Positive feedback causes more channels to open
At +40mV Na+ channels close and K+ channels open (repolarisation)
Becomes hyperpolarised with ions on wrong side (refractory period)
3Na+ out for every 2K+ in potential back to -60mV
Motor neurone
Dendrites Cell body Axon hillock Myelin sheath Node of ranvier Axon
Sensory neurone
Sensory receptor Dendron Cell body Axon Synaptic ending (in CNS)
Relay neurone
Dendrites
Duell body
Axon
Synaptic endings
Structure of my myelin sheath
Schwann cells wrapped around the axon or dendron
Significance of motor neurone
Cell body in CNS
Long axon
Significance of Sensory neurone
Long dendron
Cell body outside CNS
Short axon to CNS
Advantage of myelination
Allows action potential transmission to be faster
Don’t allow ions to move across neurone membrane
Action potential jumps from one node of Ranvier to the other
(Saltatory conduction)
Structure of synapse
Presynaptic axon Axon terminal Presynaptic knob Synaptic cleft Postsynaptic membrane
Stages of synapse
Action potential arrives
Voltage-gates Calcium ion channels open and diffuse in
Calcium ions cause vesicles to fuse with ore-synaptic membrane
Acetylcholine released
Binds to post synaptic membrane
Na+ channels open producing a generator potential
If generator potential surpasses threshold value, action potential created
Acetylcholinesterase hydrolysis and makes ethanoic acid and choline
Temporal summation
Series of action potential in the pre-synaptic neurone to produce an action potential in the post-synaptic neurone
Spatial summation
Several pre-synaptic neurones cont using to produce an action potential in the post-synaptic neurone
