KP222 Lecture Notes - Lecture 5: Exocytosis, Inhibitory Postsynaptic Potential, Second Messenger System
Lecture 5:
Larger Diameter Neurons and Myelinated Neurons Carry Signals Faster
Change in membrane because of the current
Travel down in both directions: further you get the more dispersed the charge will be
Membrane is not a good insulator: unmyelinated
Membrane potential will drop
The distance the current will travel before the neuron the drops down to 37% of the
original value is the length constant
- Membrane potential drops = length constant
- Cells that have a longer length constant they are carrying the current faster neuron
- Determines speed
Myelinated determinants
1. Resistance across the membrane (to flow)
- Add myelin to increase (more myelin more length constant)
2. Axial resistance
- Axoplasmic resistance: resistance to current flow
- Larger neurons have lower axial resistance
- Example: 401 to TO
- If has a lower resistance: longer length constant
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January 26, 2017
Excitatory postsynaptic potential: depolarizing
Inhibitory postsynaptic potential: hyperpolarizing
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Document Summary
Larger diameter neurons and myelinated neurons carry signals faster. Travel down in both directions: further you get the more dispersed the charge will be. Membrane is not a good insulator: unmyelinated. The distance the current will travel before the neuron the drops down to 37% of the original value is the length constant. Cells that have a longer length constant they are carrying the current faster neuron. Add myelin to increase (more myelin more length constant: resistance across the membrane (to flow, axial resistance. If has a lower resistance: longer length constant. Action potential depolarization voltage-gated ion channel calcium gated channel open up when depolarize calcium will move in (icf) Calcium will cause the synaptic vesicles to travel down to the active areas/zones of axon terminal. Bind to an enzyme which will breakdown the nt. Reuptake the nt but more commonly you can reuptake by breaking down the enzyme can recycle nt.
