Nervous Coordination
- Created by: tash_c1ark
- Created on: 09-02-22 10:34
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- Nervous Coordination
- Nerve Impulses
- Neurones
- Structure
- Adapted to carry rapid nerve impulses
- Shwann Cells
- wraparound axons
- Cell body
- Dendrites - carry nerve impulses towards cell body
- Axon - single fibre that carries impulses away from cell body
- axons can be myelinated
- Myelin sheath and nodes of ranvier between
- axons can be myelinated
- Structure
- Action Potential
- Stimulus opens voltage - gated sodium channels
- Influx of sodium ions cause depolarisation of axon which reaches a threshold
- Action poential - wave of depolarisation
- at +40mV, sodium channels close and potassium channels open
- Repolarisation
- hyperpolarisation - tempory overshoot of outward potassium ions
- Sodium -potassium channel returns membrane potential to -65mV
- Refractory Period
- Discrete impulses
- Limits of number of impulses
- unidirectionality
- Refractory Period
- Sodium -potassium channel returns membrane potential to -65mV
- hyperpolarisation - tempory overshoot of outward potassium ions
- Repolarisation
- at +40mV, sodium channels close and potassium channels open
- All-or-nothing response
- Action poential - wave of depolarisation
- Influx of sodium ions cause depolarisation of axon which reaches a threshold
- Stimulus opens voltage - gated sodium channels
- Resting Membrane potential
- around -65mV, in a polarised state
- Sodium potassium pump in axon membrane
- 3 sodium ions out, 2 potassium ions in
- Protein chnalles allow ions to diffuse in and out
- Membrane is more permeable to k+ ions, so some K+ ions diffuse back out
- Neurones
- Synaptic Transmission
- Synapse
- unidirectionality
- always from presynaptic neurone to postsynaptic neurone
- inhibitory synapses
- chloride ions enter postsynaptic neurone
- hyperpolarisation
- chloride ions enter postsynaptic neurone
- junction between 2 neurones
- neuromuscular junction - between motor neurone and muscle end plate
- unidirectionality
- Synapse
- Nerve Impulses
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