Concept explainers
To review:
The following:
Explanation of all-or-none law of action potentials.
Effects of raised stimulus strength on action potential production.
Ways in which refractory periods exerts effect on the frequency of action potential production.
Introduction:
When a part of axon membrane gets depolarized, the positive feedback on sodium ion channel permeability makes the membrane potential increase above +30 millivolt. This slight increase does not move more than +30 millivolt as sodium ion channels tend to close quickly when the potassium ion channels open up. Hence, the size or amplitude of action potential becomes all-or-none. Moreover, action potentials are produced when stimulus of a prescribed intensity is steadily maintained at a particular point of axon.
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Human Physiology
- Explain how stimulus intensity can be coded by action potentials if all action potentials are identical.arrow_forwardFigure Ql shows the typical electrical recording of movement artifacts during the resting potential and also the action potential when an adequate stimulus is delivered. Potential overshoot (, > 0) Movement artifact Action potential -80 Stimulus artifact Resting potential Figure Ql In your own words, discuss the phenomena occur during the resting state and active state until the equilibrium potential is established. (a) Membrane potential (m), mVarrow_forwardBased on the graph, how soon could another action potential be easily initiated (at the end of the relative refractory period) after the first stimulus? (Base your answer to this question on the graph below depicting an action potential.) less than 0.5 msec 1 msec 2 msec 3 msec 4 msecarrow_forward
- Identify the important physiological structures involved in action potential; then, explain in detail how one nerve action potential causes one muscle action potential.arrow_forwardDescribe the following terms: specificity, stimulus, receptor potential, synapse, neurotransmitter, graded potential, an action potential?arrow_forwardDescribe the direction of action potential propagation relative to the CNS in the spinal nerves, dorsal roots, and ventral roots. List some of the responses stimulated by the autonomic nervous system in (a) a person who is extremely angry and (b) a person who has just finished eating and is now relaxing.arrow_forward
- MC: Which of the following changes to an action potential indicates a larger stimulus? Increased frequency Increased wavelength Increased amplitude Increased speedarrow_forwardWhich of the following is true regarding the difference between graded and action potentials? a.) Action potential occur only when the surface of the neuron is myelinated, but graded potentials occur in both in both myelinated and non-myelinated neurons. b.) The magnitude of action potential depends on the magnitude of the stimulus, whereas graded potentials are all or none. c.) The magnitude of graded potential depends on the magnitude of the stimulus, whereas action potentials are all or none.arrow_forwardThe action potential is fired by: a- Opening K+ channels by subthreshold response b- Opening Na Channels by threshold response c- Opening K+ channels by threshold response d- Opening Na by subthreshold responsearrow_forward
- Human Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning