Action Potential-A Narration

HAPS Learning Goals and Objectives; A&P Module H

LO1-01: Describe the general functions of the nervous system.

LO 5-01: Identify and describe the major components of a typical neuron (e.g., cell body, nucleus, nucleolus, chromatophilic substance [Nissl bodies], axon hillock, dendrites, and axon) and indicate which parts receive input signals and which parts transmit output signals.

LO7-01: List the major ion channels of neurons and describe them as leak (leakage or passive) or voltage-gated channels, mechanically gated channels, or ligand-gated (chemically-gated) channels, and identify where they typically are located on a neuron.

LO7-02: Describe the physiological basis of the resting membrane potential (RMP) in a neuron including the ion channels involved, the relative ion concentrations, and the electrochemical gradient.

LO7-04: Define and describe depolarization, repolarization, hyperpolarization, and threshold.

LO7-05: Compare and contrast graded potentials and action potentials, with particular attention to their locations in the neuron and the ions and ion channels involved in each.

LO7-06:Label a voltage-versus-time diagram of an action potential with the ions involved in each phase, the direction of their movement across the membrane, and the terms depolarize, repolarize, and hyperpolarize.

LO7-07: Describe the physiological process involved in the conduction (propagation) 2 of an action potential, including the types and locations of the ion channels involved.

LO7-08:Describe the importance of voltage-gated channels in the conduction (propagation) of an action potential.

Learning Objectives for the Activity:

Describe the function of the neuron in the overall function of the nervous system.
Describe the process of propagating an action potential along the axon of the neuron.
Differentiate between the process of propagation for a myelinated axon and an unmyelinated axon.

Key Terms and Background

Key Terms:

Depolarization: change in the membrane potential that is more positive than the resting potential

Hyperpolarization: change in the membrane potential that is more negative than the resting potential

Action Potential: change in membrane potential that results in a change in the cellular function (typically with neurons).

Threshold Potential: the minimum change in the membrane potential that is necessary to reach an action potential

Latency Period: time between stimulus being received, threshold being reached, and action potential being conducted.

Refractory Period: time between one action potential and the next

Open Channel: state where ion channels allow the specific ion to flow across the membrane.

Inactive Channel: state where the channel is between being open and closed, it is associated with the refractory period.

Inhibitory Potential: a change in the membrane potential that makes it harder for the cell to reach an action potential (hyperpolarizing areas of the membrane).

Excitatory Potential: a change in the membrane potential that makes it easier for the cell to reach an action potential (depolarizing areas of the membrane).

Background information:

The neuron is a specialized cell that passes a chemo-electrical signal from the cell body of one neuron to another neurons cell body through the opening and closing of “voltage-gated channels” within the membrane of the dendrite and axon of the neuron. To allow the signal to remain constant, the voltage-gated channels must coordinate their oping and closing in such a way that once threshold potential has been reached, the signal will only move in one direction. From the cell body (axon hillock) along the axon to the axon terminals and synaptic membranes. The actions of the ion channels function at speeds that allow those involved with the action potential to establish the resting potential, quickly change to the action potential, and then regain the resting membrane potential fast enough to allow the next action potential to be sent along the neuron or at the axon hillock to initiate a new action potential.

Activity

Part 1:

1. Watch the video with your group. Don’t play with the audio level (there is none).

2. While you are watching the video:

a. Develop a script that describes the events that are being presented in the video as it relates to the overall function of the neuron and relate it to the overall function of neurons for the nervous system.

i. Make sure to provide the necessary details:

1. The actions of the voltage gated channels

2. The movement of ions and the changes of the membrane potentials that occur as the ions move.

b. Using the program of your choice and your script, re-record the video but provide the narrations that were missing from the video to give the necessary details to other students for how neurons are able to conduct an action potential along the membrane of the axon.

Part 2:

1. Peer Review:

a. Based on the group you have been paired with and using the rubric, provide corrective feedback to the group’s script and narrated video

2. Corrections:

a. Using the corrective feedback provided to you, edit your script and your narrated video

neuron-action-potential.mp4

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