- University of South Carolina - All Campuses
- Exercise Science
- Exercise Science 224
- test 1
Last Modified: 2012-02-07
Related Textbooks:Human Anatomy & Physiology, 8th Edition
- Measure of potential energy generated by separated charge
- voltage measured between 2 pts.
- flow of electrical charge(ions) between 2 points.
- hindrance to charge flow(provided by the plasma membrane)
- substance with high electrical resistance
- substance with low electrical resistance
- Leakage(nongated) Channels: always open
- Gated Channels:
- Chemically gated (ligand Gated) channels: open when appropriate neurotransmitter binds to receptor allowing simultaneous movement of Na and K
- Votage-Gated channels: open due to change in membrane voltage
- Mechanically gated channels
- Ions diffuse quickly across the membrane along their electro-chemical gradients
- Along chemical concentration gradients form high to low concentration
- Along electrical gradients toward opposite electrical charge
- Difference in electrical Potential diff between interior and exterior of a resting cell
- Can be generated by diffs in ionic makeup or ICF and ECF. Also generated by differential permeability of the plasma membrane
- Graded Potentials: Incoming short-distance signals. Specific to input. Occur at dendrites, cell bodies
- Action Potentials: Long-distance signals of axons. Occur at axons only
- Short lived and localized changes in membrane potential that can be either depolarizations or hyperpolarizations.
- Spread as local currents and change the membrane potential of adjacent regions
- Occur when gated ion channels are open.
- Magnitude varies w/ stimulus strength
- Decrease in magnitude w/ distance. Short distances prodominantly
- Thousands of Sodium Potassium Pumps
- Membrane is depolarized by 15 to 20 mV
- Na permeability increases and Na influx exceeds K efflux
- Possitive feedback cycle
- Stronger Stimulus = More Action Potentials
- Absolute refractory period: Time from opening of Na channels until the reseting of the channels. This ensures that each AP is all-or-none event
- Relative Refractory Period: Repolarization
- Group A Fibers- Largest diameter, Myelinated, Fast(ex. somatic sensory and motor fibers)
- Group B Fibers- Intermediate diam. lightly myelinated, moderately fast.(ex. ANS fibers)
- Group C Gibers- Smallest diameter, Unmyelinated, slow(ex. ANS Fibers)
- Specialized for release and reception of neurotransmitters
- Composed of 2 parts:
- Axon Terminal- presynaptic neuron
- Receptor region- postsynaptic neuron
- amount of neurotransmitter released
- Time the neurotransmitter in the area
- Excitatory Postsynaptic Potentials(EPSP)
- Inhibitory Postsynaptic Potentials(IPSP)
- Ligan-gated channels
- Action is immediate and brief
- Receptors are channels. Na influx-depolarization
- Receptors allow Cl influx or K efflux(hyperpolarization)
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