KINE 2031 Lecture Notes - Lecture 11: Inhibitory Postsynaptic Potential, Ion, Synaptic Vesicle
2 Jul 2018
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Strength of Stimuli & Frequency of AP
-Stroger stimuli doesn’t produce larger AP, but frequency increases/sec. Stronger stimuli causes more
neurons to reach threshold, increasing total information sent to CNS
-Speed at which AP travels down axon depends on:
1. Whether fiber is myelinated
2. Diameter of Fibre
-Contiguous fibers are unmyelinated slow conduction
-Saltatory conduction in myelinated fibers faster conduction
Myelinated & Speed of Conduction
-Myelinated fibers are covered w/myelin at regular internals.
-Myelin composed of lipids, acts as insulator to prevent current leakage, saltatory conduction
-Myelin-forming cells are:
ooligodendrocytes in brain & spinal cord of CNS
oSchwann cells in nerves in PNS
-Nonmyelinated regions called nodes of Ranvier. Nodes of Ranvier have voltage gated Na+ channels
concentrated to produce AP.
-Urgent information transmitted quickly via myelinated fibres, conserves energy
Synapses & Neural Integration
-Neuron may terminate on three structures:
oMuscle
oGland
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Document Summary
Stroger stimuli doesn"t produce larger ap, but frequency increases/sec. Stronger stimuli causes more neurons to reach threshold, increasing total information sent to cns. Speed at which ap travels down axon depends on: whether fiber is myelinated, diameter of fibre. Saltatory conduction in myelinated fibers faster conduction. Myelinated fibers are covered w/myelin at regular internals. Myelin composed of lipids, acts as insulator to prevent current leakage, saltatory conduction. Myelin-forming cells are: oligodendrocytes in brain & spinal cord of cns, schwann cells in nerves in pns. Nodes of ranvier have voltage gated na+ channels concentrated to produce ap. Urgent information transmitted quickly via myelinated fibres, conserves energy. Neuron may terminate on three structures: muscle, gland, another neuron. Synapses is junction b/t two neurons (or b/t two excitable cells) Dendrites receive synaptic inputs from other axon terminals. Axon terminals of presynaptic neurons conducts ap towards synaptic knob. Synaptic knob contains synaptic vesicles, which stores chemical messengers- neurotransmitter.
