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Neurone - highly specialized cell. c. d. e. dendron. Cell body. axon. f. Myelinated Nerve. Node of Ranvier. White fat from Schwann cell. axon. Myelin sheath: Faster nerve impulse, Protection, Insulation. Sensory neurone. Types of Neurones. Relay neurone. Motor neurone. 1. 3.
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Neurone - highly specialized cell c d e
dendron Cell body axon
Myelinated Nerve Node of Ranvier White fat from Schwann cell
axon Myelin sheath: Faster nerve impulse, Protection, Insulation
Sensory neurone Types of Neurones Relay neurone Motor neurone 1 3 CNS 2
1 3 2
Facilitated diffusion Na-K pump
Resting Membrane Potential d b -ve c
Action Potential: change of membrane permeability to Na & K channel opens = permeability increases
Action Potential (-70 to +40mV) K Na (Na influx) K Na=0 (K outflux) K Na=0 (too much K outflux) K Na=0 (K outflux) K Na=0 (K outflux)
K Na K Na=0 repolarization depolarization K ,Na=0 hyperpolarization polarization K Na=0 K Na=0
Na per>>K per K per >>Na per potential difference K per>Na per K per> Na per K per Na per
All-or-nothing Law • freq. only
Propagation of Nerve Impulse Wave of negativity along axon surface
polarization repolarization p.d depolarization Pump out Na & prepare for next impulse
Non-myelinated Myelinated
Factors affect Transmission rate • Axon Diameter (thicker > faster) • Myelin Sheath (faster) • Temperature (higher > faster)
Synaptic Transmission presynaptic postsynaptic presynaptic
Nucleus of cell body Cell body Synaptic knob axon
Synaptic vesicle Synaptic knob mitochondria Presynaptic membrane Synaptic cleft Postsynaptic membrane
Synaptic Transmission depolarization a presynaptic b c postsynaptic d) Na influx, depolarizarion
a b Changes in synaptic transmission c d e f
Function of Synapses • Ensure impulse to pass in one direction • Prevent damage of effectors due to over stimulation • Act as junctions for dividing up and merging of neurones