Muscles, Part 2 - Organismal Level: Crash Course A&P #22

2015-06-15

[public] 2.03M views, 27.7K likes, 282 dislikes audio only

Hank calls in a friend to do his push-ups for him today to explain how skeletal muscles work together to create and reverse movements. Hank and Claire also demonstrate the role size plays in motor units, the three-phase cycle of muscle twitches, and how the strength and frequency of an impulse affect the strength and duration of a contraction. This episode also explains twitch summation, tetanus, and isotonic vs. isometric movements.

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Chapters:

Introduction: Heavy Lifting 00:00

How Muscles Push & Pull 1:13

Functional Muscle Groups: Prime Movers, Antagonists, and Synergists 2:27

Motor Units 3:49

3 Phases of Muscle Twitches: Latent, Contraction, Relaxation 4:41

Graded Muscle Responses 5:22

Temporal Summation vs Tetanus 6:19

Multiple Motor Unit Summation (Recruitment) 7:07

The Size Principle of Recruitment 7:52

Isotonic vs Isometric Movements 8:50

Review 9:28

Credits 9:59

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