20080929

20080929 - PnB 250 page #1 Lecture 14 Muscle Contraction:...

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PnB 250 page #1 Lecture 14 Muscle Contraction: muscle tension vs. load ( f o r c e ) ( f o r c e ) Types of contraction: Isometric contraction: same length - tension = load Crossbridges form and reform but sarcomeres remain the same length. Isotonic contraction: same tension - length (movement) Latent period: time required for generation of the active contractile state. From AP to beginning of shortening – last a few milliseconds. Relaxation time : peak of contraction to zero tension (10 – 100 msecs) Å depends on muscle type Tension Time (ms) latent period relaxation time 50 100 Isometric twitch (single AP)
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PnB 250 page #2 latent period Summation Caused by arrival of a new action potential while the muscle is still contracting (this results in additional force). Shortening Time (ms) 50 100 light load Isotonic twitch intermediate load heavy load AP AP AP AP AP AP AP fatigue tetanus AP AP twitch summation AP AP AP shortening time Æ
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PnB 250 page #3 Tetanus maximal summation. APs occur at a frequency which prevents relaxation Æ until fatigue .
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This note was uploaded on 11/16/2011 for the course PNB 2250 taught by Professor Renfro during the Spring '08 term at UConn.

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20080929 - PnB 250 page #1 Lecture 14 Muscle Contraction:...

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