KIN 324K Chapter Notes - Chapter 3: Neuroglia, Myelin, Cell Membrane

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22 Dec 2016

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Returns to resting membrane potential and becomes less than resting membrane potential absolute refractory period - -no amount of stimulus is able to generate a second action potential. Na+ channels opened then closed in inactivated state. Remain closed until potential is almost to the resting potential. Ensures that action potential moves in one direction only. Occurs during depolarization/repolarization relative refractory period - -another action potential is possible if the stimulation of the membrane is greater than the initial stimulus. Occurs during hyperpolarization threshold - if summation is successful, _ can be met if _ is met, action potential occurs. Action potential only occurs at nodes of ranvier continuous conduction - -must go all the way through action potential. Both epsp or both ipsp work together to make a stronger signal. One epsp and one ipsp don"t work together. Stronger the close the synapses are together temporal summation - -rhythm/timing of release of neurotransmitters.

Related Questions

Which of the following statements is FALSE? (choose one)

A.	Voltage-gated sodium (Na+) channels open in the dendrites and cell body during a local, graded potential.

B.	During repolarization, potassium ions are leaving the cell (K+ is diffusing out of the cell), and the inside of the cell becomes more negative

C.	If someone damaged an efferent motor neuron, they could feel pain, but not respond to move away from the pain

D.	Myelin serves as electrical insulation and increases the speed at which an action potential travels along the axon

E.	Movement of ions can be excitatory (if sodium ligand-gated channels bind the neurotransmitter), or inhibitory (if potassium ligand-gated channels bind the neurotransmitter)

1.	Action Potentials
2.	Graded Potentials

Match the characteristic/descriptor in the left-hand column withthe correct type of change in membrane potential listed in theright-hand column.

Question 16 options:

12	propagate along the length of the axon with no decrease inmagnitude as they move away from their site of origin
12	are decremental changes in membrane potential - meaning they arethe type that decrease in magnitude as they spread further fromtheir sites of origin
12	cause an actual reversal of membrane potential during which theinside of the cell membrane temporarily becomes positive withrespect to the outside of the cell membrane
12	are non decremental changes in membrane potential - meaning theypropagate along the plasma membrane with no observable decrease inintensity as they move further and further from their sites oforigin
12	occur in the 'receptive' regions of the neuron - including thecell body and dendrites - in response to opening of ligand-gatedion channels
12	begin at the axon hillock and propagate to the axon terminal
12	occur along the length of the axon in response to opening ofvoltage-gated sodium and potassium ion channels
12	weaken as they spread further and further along the plasmamembrane and away from their site of origin
12	required no 'threshold' change in membrane voltage to occur.
12	occur in 'all or none' fashion

blushjellyfish481

Santiago Ramon y Cajalâs theory of dynamic polarization refers to the:

(a)membrane potential of a neuron at rest.

(b)membrane potential of a neuron firing action potentials.

(c)opening and closing of gated channels in the membrane.

(d)one way flow of information in neurons from dendrites to axon terminals.

(e)one way flow of information in neurons from axon terminals to dendrites.

Over the course of scientific history, there are many examples of scientists reaching the right conclusion for the wrong reasons. When Schwann first proposed that the nervous system was made of individual cells, he based it on observations of:

(a)synapses.

(b)dendrites

(c)axon terminals.

(d)astrocytes.

(e)Nodes of Ranvier.

The synaptic cleft was finally seen in the 1950s. What prevented scientists from seeing it earlier?

(a)The resolution of the light microscope.

(b)They were looking in the wrong place.

(c)Their tissue was not appropriately stained.

(d)Myelination of the axons.

(e)all of the above

The resting membrane potential of a neuron is approximately:

(a) +65 V

(b) +65 mV

(d) -65 mV

What is largely responsible for the resting membrane potential in a neuron?

(a)Axonal insulation by myelin

(b)Voltage-Gated Sodium Channels

(c)The Action Potential

(d)Potassium Leak Channels

Which of the following would DECREASE the propagation velocity of an action potential down an axon?

(a)Increase in axon diameter

(b)Increase myelination between nodes of Ranvier

(c)Remove myelination between nodes of Ranvier

(d)Decrease density of voltage-gated Na+ channels except at the Nodes of Ranvier

The resting membrane potential of a neuron can be estimated using the:

(a)Nernst equation

(b)Goldman equation

(c)Hodgkin and Huxley equation

(d)Ohmâs law

18. What would happen to the resting membrane potential of a neuron if you added K+ to the extracellular fluid?

(a)Resting membrane potential would increase (become more positive)

(b)Resting membrane potential would decrease (become more negative)

(c)Resting membrane potential would not change

(d)Resting membrane potential would be abolished

. Which of the following statements is FALSE for Graded Potentials

(a)Magnitude changes with magnitude of triggering stimulus

(b)Magnitude decreases with distance from initial site

(c)Cannot be summed

(d)No refractory period

In the nervous system, the strength of the stimulus is coded into:

(a)The frequency of action potentials generated

(b)The amplitude of action potentials generated

(c)Both the frequency and amplitude of action potentials generated

(d)The duration of individual action potentials generated

Ion movement during both the depolarization and repolarization phases of an action potential are the result of:

(a)active transport pumps along the neuron membrane.

(b)diffusion of ions down their electrochemical concentration gradients.

(c)negative feedback loops.

(d)All of the above

At the peak of the action potential, the membrane potential is:

(a)Exactly at the Na+ equilibrium potential

(b)Greater (more positive) than the Na+ equilibrium potential

(c)Above 0 mV but less positive than the Na+ equilibrium potential

(d)0 mV

KIN 324K Chapter Notes - Chapter 3: Neuroglia, Myelin, Cell Membrane

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