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1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Human Biology Sylvia S. Mader Michael Windelspecht Chapter.

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Presentation on theme: "1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Human Biology Sylvia S. Mader Michael Windelspecht Chapter."— Presentation transcript:

1 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Human Biology Sylvia S. Mader Michael Windelspecht Chapter 12 Muscular System Lecture Outline Part 3

2 2 What role does ATP play in muscle contraction and rigor mortis? ATP is needed to attach and detach the myosin heads from actin. After death, muscle cells continue to produce ATP through ______________ and muscle cells can continue to contract. When ATP runs out, some myosin heads are still attached and cannot detach, causing rigor mortis. Rigor mortis and body ___________ may be used to estimate time of death Skeletal Muscle Fiber Contraction

3 3 Terms to describe whole muscle contraction _________ – a nerve fiber and all of the muscle fibers it stimulates ____________ – a single contraction lasting a fraction of a second ____________ – an increase in muscle contraction until the maximal sustained contraction is reached 12.3 Whole Muscle Contraction

4 4 _________ – maximal sustained contraction ___________ – a continuous, partial contraction of alternate muscle fibers causing the muscle to look firm 12.3 Whole Muscle Contraction Terms to describe whole muscle contraction

5 5 Physiology of skeletal muscle contraction Figure 12.9 The three phases of a single muscle twitch and how summation and tetanus increase the force of contraction Whole Muscle Contraction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Force relaxation period contraction period latent period Time fatigue tetanus summation Stimuli Time Force b. Stimulus a.

6 6 Where are the fuel sources for muscle contraction? Stored in the muscle –Glycogen –Fat In the blood –Glucose –Fatty acids Exercise time (hr) muscle triglycerides plasma fatty acids blood glucose muscle glycogen Percentage of energy expenditure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure The sources of energy for muscle contraction Whole Muscle Contraction

7 7 What are the sources of ATP for muscle contraction? Limited amounts of ATP are stored in muscle fibers. Creatine phosphate pathway (CP) – ________ way to acquire ATP but only sustains a cell for _______; builds up when a muscle is resting Fermentation – fast-acting but results in _______ build up Cellular respiration (aerobic) – not an immediate source of ATP but the best _________ source 12.3 Whole Muscle Contraction

8 8 Acquiring ATP for muscle contraction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anaerobic Aerobic creatine phosphate glycogen glycogen or fatty acids fermentation O2O2 creatine lactateCO 2 + H 2 O ATP a.b.c Figure The three pathways by which muscle cells produce the ATP energy needed for contraction Whole Muscle Contraction

9 9 Muscle fibers come in 2 forms Fast-twitch fibers Rely on CP and fermentation (anaerobic) Adapted for strength Light in color Few mitochondria Little or no myoglobin Fewer blood vessels than slow-twitch 12.3 Whole Muscle Contraction

10 10 Muscle fibers come in 2 forms Slow-twitch fibers Rely on aerobic respiration Adapted for endurance Dark in color Many mitochondria Myoglobin Many blood vessels 12.3 Whole Muscle Contraction


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