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Exercise Science 224 with Thompson at University of South Carolina - All Campuses

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By: robert macbain
Created: 2012-02-05
Size: 35 flashcards
Views: 35

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Define Voltage, Potential Difference, Current

Measure of potential energy generated by separated charge
voltage measured between 2 pts.
flow of electrical charge(ions) between 2 points.

Define Resistance, Insulator, Conductor

hindrance to charge flow(provided by the plasma membrane)
substance with high electrical resistance
substance with low electrical resistance

What are the 2 types of Ion Channels?

Leakage(nongated) Channels: always open
Gated Channels:

What are the 3 types of Gated Channels? Explain the 2 main types

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

What happens when gated channels are open? What does this create

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

What is Resting Membrane Potential? What 2 ways can it be generated?

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

What are the two types of Membrane Potentials that act as Signals? How are they different?

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

What are the 2 types of changes in membrane potential?

1.) Depolarization- membrane potential moves towards zero

2.)Hyperpolarization- membrane potential decreases, inside becomes more negative

What are Graded Potentials? How do they spread? When do they occur? What effects magnitude?

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

WHy does membrane potential decay with distance?

B/c current is lost through the leaky plasma membrane. The voltage is decremental

The role of ______________________ is Ionic redistribution back to resting conditions?

Thousands of Sodium Potassium Pumps

What step restores the resting electrical conditions of the neuron but doesn't restore the resting ionic conditions?

Repolarization

WHat is occurring at threshold? WHat type of cycle is this? What is the result of a stronger stimulus?

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

How does the CNS determine stimulus intensity?

By frequency of impulses

What are the 2 refractory periods?

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

In which refractory period can you have another Action Potential(depolarize again)?

Relative Refractory Period if there is a very large stimulus

What is occuring during Relative Refractory period? (4)

1.) most NA channels have returned to resting state

2.) Some K channels are still open

3.) Repolarization

4.) Threshold for AP generation is elevated

What two things effect conduction velocity?

Axon Diameter(larger= Faster) and Myelination (myelination= faster)

How are nerve fibers classified?(3)

Diameter

Degree of myelination

Speed of conduction

Explain the 3 Nerve Fiber Classification?

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)

WHat is a synapse?

A junction that mediates info transfer from one neuron to another neuron or an effector cell

Whats the diff. betwee presynaptic neuron and postsynaptic neuron?

Presynaptic conducts impulses toward the synapse and postsynaptic neuron transmits impulses away from synapse

How fast are electrical synapses? What direction do they travel?

Very Rapid

Unidirectional or Bidirectional

Ex. Embryonic nervous tissue, brain regions, and heart

What are chemical synapses specialized for? What are there 2 parts

Specialized for release and reception of neurotransmitters
Composed of 2 parts:

Axon Terminal- presynaptic neuron
Receptor region- postsynaptic neuron

how does one neuron communicate with another neuron

via neurotransmitters

What is synaptic delay?

rate limiting step of neural transmission(.3-5ms)

What kind of Potentials are postsynaptic potentials? How are their strengths determined? What are the 2 types?

Graded Potentials

amount of neurotransmitter released
Time the neurotransmitter in the area

Excitatory Postsynaptic Potentials(EPSP)
Inhibitory Postsynaptic Potentials(IPSP)

What does binding of neurotransmitter do for EPSP? This causes? What does EPSP help trigger?

•Neurotransmitterbinds to and opens chemically gated channels that allow simultaneous flow of Na+ and K+ in opposite directions

•Na+ influx is greater that K+ efflux, causing a net depolarization

•EPSPhelps trigger AP at axon hillock if EPSP is of threshold strength and opens thevoltage-gated channels

What does neurotransmitter open channels for IPSP? This causes? Reduces the postsynaptic neuron's ability to?

•Neurotransmitterbinds to and opens channels for K+ or Cl–

•Causesa hyperpolarization (the inner surface of membrane becomesmore negative)

•Reducesthe postsynaptic neuron’s ability to produce an action potential

2 types of Neurotransmitter Receptors

1.Channel-linked receptors (Direct)

•Examples:ACh and amino acids

2.G protein-linked receptors (Indirect)

•Examples:biogenic amines, neuropeptides, and dissolved gases

Channel linked receptors a.k.a? WHat is there action like? What occurs at receptors for Excitatory? Inhibitory?

Ligan-gated channels
Action is immediate and brief
Receptors are channels. Na influx-depolarization
Receptors allow Cl influx or K efflux(hyperpolarization)

Neuronal Pools

•Functional groups of neurons that:

–Integrate incoming information

–Forward the processed information to other destinations

About this deck

By: robert macbain
Created: 2012-02-05
Size: 35 flashcards
Views: 35

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj