BIOC32H3 Lecture 11: Lecture 11 - Comparative Skeletal Muscle Physiology

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periwinklerhinoceros137

29 Apr 2011

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Section insect asynchronous flight muscles p. 408 411. Section motor control in arthropods p. 413 414. aps are required to come in rapid succession and result in temporal summation (a single fibre with summation) Isometric: less than full production (a tetanic contraction (or tetanized state) occurs when a motor unit has been maximally stimulated by its motor neuron. This occurs when a muscle"s motor unit is stimulated at a sufficiently high frequency of multiple impulses. If stimuli is delivered slow enough, the tension in the muscle will relax between successive twitches. If stimuli are delivered at high frequency, then the twitches will add up, resulting in tetanic contraction. ) depends on units of muscle function activated at a time and how long they remain activated. vertebrate motor units contains 1000s of fibres that have 100s neurons innervating it.

Related Questions

1) Muscle tone is the result of:

a) asynchronous firing of motorunits

b) incomplete tetanus.

c) multiple muscle twitches.
d) multiple motor unit summation.

2) Under normal circumstances, at the level of single skeletalmuscle fibers, there are:

a) all-or-nonr responeses

b) graded contractions, depending onstimulus input

c) rapid spasmodic contractions, resulting in themain contraction

3) The muscles of the eye need to make precise small motormovements. Therefore, you would find large motor units in the eye,while you would find small motor units in postural muscle such asthe thigh.

a) True

b) False

The stimulus interval has a profound effect on the contractionforce of the muscle. In your own words explain what happened whenthe muscle was stimulated in rapid succession. What was the minimumtime required for the subject's muscle twitches to add together(summation)?

You use a short period electrical stimuli to observe musclefibers contracting continuously (tetanus). Chemical
agents can cause tetanus by interfering with the motor neurons.These agents include a toxin produced by
the soil bacterium Clostridium tetani. One of the symptoms of theseagents is called 'spastic paralysis'! Explain
in your own words why these agents would be a bad thing for you andyour muscles.

sapphirealpaca560

Short Essay: Explain how a maximal repetitivestimuli to a to a muscle's nerve produces a maximaltetanic force that is equal in amplitude to the muscle's activestate tension (force), but considerably greater than maximal singletwitch force that the organ produces with just one single maaximalstimulus.

Note: by maximal stimulus, I mean that each stimulus isstong enough to produce action potentials (one AP per stimulus) ineach and every motor unit in the muscle organ.

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BIOC32H3 Lecture 11: Lecture 11 - Comparative Skeletal Muscle Physiology

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