Action potential and strength of muscle contraction?

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Discussion Overview

The discussion revolves around the relationship between action potentials, motor units, and muscle contraction strength, focusing on the anatomical and physiological aspects of the nervous system, particularly the distinction between nerves and neurons. It includes questions about the control of muscle contraction strength and the implications of nerve branching in the central and peripheral nervous systems.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether organs supplied by a single motor neuron can control contraction strength.
  • Another participant asserts that the response of a motor unit is all-or-none, but the overall muscle strength depends on the number of motor units activated.
  • Concerns are raised about the action potential traveling through nerve branches and affecting unnecessary structures, prompting a clarification about the distinction between the central nervous system and peripheral nervous system.
  • One participant emphasizes the difference between nerves (bundles of axons) and neurons, suggesting that a single nerve can innervate an organ with multiple neurons.
  • A later reply acknowledges the clarification about nerves and neurons, indicating a resolution of confusion on that point.

Areas of Agreement / Disagreement

Participants express differing views on the implications of having a single motor neuron for muscle contraction strength, and there is some confusion regarding the terminology of nerves versus neurons. While one participant acknowledges the clarification provided, the discussion remains unresolved regarding the broader implications of nerve branching and muscle control.

Contextual Notes

There are limitations in the discussion regarding assumptions about the nervous system's structure and function, particularly concerning the definitions of nerves and neurons and their roles in muscle contraction.

sameeralord
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Hello guys,

Although the response of a motor unit is all-or-none, the strength of the response of the entire muscle is determined by the number of motor units activated. Nerve impulses passing down a single motor neuron will thus trigger contraction in all the muscle fibers at which the branches of that neuron terminate. and this is a motor unit.

1.My question is some organs are supplied only with one motor neuron, is it impossible for them to control the strength of their contraction?
2.Also this is just about the central nervous system. Since CVS has many nerves which are branches of other nerves, when an action potential is sent how come this action potential doesn't travel through the branches and innervate unnessecary structures?

Thanks for anyone who is going to help :smile:
 
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1/ No.
2/ idem.
 
I think you're confusing the terms nerve and neuron.

A nerve is a bundle of neuron axons (surrounded by endoneurium, perineurium and epineurium, which are connective tissue layers that hold them together). You don't have a single NEURON innervating an organ, but you may have a single NERVE innervating it, with MANY neurons.

Also, as soon as you're talking about nerves, by definition, you're talking about the peripheral nervous system, not the central nervous system, so your second question doesn't make sense to me.
 
Moonbear said:
I think you're confusing the terms nerve and neuron.

A nerve is a bundle of neuron axons (surrounded by endoneurium, perineurium and epineurium, which are connective tissue layers that hold them together). You don't have a single NEURON innervating an organ, but you may have a single NERVE innervating it, with MANY neurons.

Also, as soon as you're talking about nerves, by definition, you're talking about the peripheral nervous system, not the central nervous system, so your second question doesn't make sense to me.

Yes you are absolutely correct. I went back and read from scratch about nerves,neurones and connective tissue you talked about and worked it out. Thanks for the help :smile:
 

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