PHED-2506EL Lecture Notes - Lecture 7: Skeletal Muscle, Motor Neuron, Motor Unit
14 Dec 2018
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Lecture 7: muscles and muscle tissue part 2. Skeletal muscle contracts with varying force and different periods of time in response to our needs: motor unit: nerve-muscle functional unit. Increase in frequency of stimulation: causes temporal summation: higher frequency=greater strength of contraction. Increase in strength of stimulation: causes recruitment: stronger stimulation=stronger contraction. Muscle response to changes in stimulus frequency: nervous system can achieve greater muscular force by increasing firing rate of motor neurons. If two identical stimuli are delivered to a muscle in rapid succession, the second twitch will be stronger than the first: called temporal summation, this occurs because: second contraction begins before muscle is completely relaxed. Isotonic and isometric contractions muscles: main difference is that one has change in muscles in length. Isotonic contractions: when muscle tension developed overcomes the load (muscle shortens: concentric contraction: muscle shortens, eccentric contractions: muscle generates force as it lengthens.
