Question

3. A motor unit is said to be all or none. In your own words, explain how this is different that whole muscle contraction. Explain the difference between a large and small motor unit examples of each (not the ones from the reading or PowerPoint) (2pts) 4. Unfortunately, we cannot change the type of muscle fibers we are born with, but we can still train all of the fibers we do havet Since most of us aren't superstar athletes, we can b from a good exercise routine that contains a bit of both types of exercise. For those that naturally have more slow twitch fibers, which type of exercise suits them best? Why? (2pts) Which type of exercise suits people that naturally have more fast twitch fibers? Why? (2pts)

Answer 1

According to the all or none law , the nerve or the muscle shows response against a stimulus in a positive or negative way . Either the muscle and nerve respond to the the maximum value or do not respond at all . The given stimulus should be greater than the threshold stimulus . In a single unit muscle fibre , the single unit muscle fibre respond to the stimulus which is threshold for suprathreshold in intensity . Single unit motor fibres do not respond to the subthreshold stimulus . In the whole muscle contraction , it is made up of more than one single motor neurone fibre , hence , with the increase in the intensity of stimulus more and more motor unit is stimulated resulting in the higher and higher contraction. A certain point is achieved when all the muscle fibre are contracted , this is known as the the threshold stimulus for the muscle . The small motor unit innervate very few number of muscle fibres and the large motor unit innervate high number of muscle fibres . The conduction velocity of the large motor unit fibres are very high as compared to the small motor unit fibre . Resting membrane potential is high in case of small motor unit . The large motor neurone fibres supplies the thigh and the back region muscles . Whereas , the small motor unit supplies the muscle of the face.

Plye NA Date Interveyson laying Isyn Sufalt O large diameter motor neuron. diameter mootor newlon conduction Rm is tow & Louduction velocity is high a slow twitch type 1 fibre - Action Potential Vm1 Theehold of Rest EPSE Theashold O

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