cva a&p - chapter 6b: muscle contraction

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PowerPoint ® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PART B 6 The Muscular System

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Page 1: CVA A&P - Chapter 6b: Muscle Contraction

PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

PART B6

The Muscular System

Page 2: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

The Nerve Stimulus and Action Potential

Skeletal muscles must be stimulated by a motor neuron (nerve cell) to contract

Motor unit—one motor neuron and all the skeletal muscle cells stimulated by that neuron

Page 3: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

The Nerve Stimulus and Action Potential

Neuromuscular junction

Association site of axon terminal of the motor neuron and muscle

Page 4: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

The Nerve Stimulus and Action Potential

Figure 6.5a

Page 5: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

The Nerve Stimulus and Action Potential

Synaptic cleft

Gap between nerve and muscle

Nerve and muscle do not make contact

Area between nerve and muscle is filled with interstitial fluid

Page 6: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

The Nerve Stimulus and Action Potential

Figure 6.5b

Page 7: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Transmission of Nerve Impulse to Muscle

Neurotransmitter—chemical released by nerve upon arrival of nerve impulse

The neurotransmitter for skeletal muscle is acetylcholine (ACh)

Acetylcholine attaches to receptors on the sarcolemma

Sarcolemma becomes permeable to sodium (Na+)

Page 8: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Transmission of Nerve Impulse to Muscle

Sodium rushes into the cell generating an action potential

Once started, muscle contraction cannot be stopped

Page 9: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

The Sliding Filament Theory of Muscle Contraction

Activation by nerve causes myosin heads (cross bridges) to attach to binding sites on the thin filament

Myosin heads then bind to the next site of the thin filament and pull them toward the center of the sarcomere

This continued action causes a sliding of the myosin along the actin

The result is that the muscle is shortened (contracted)

Page 10: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

The Sliding Filament Theory of Muscle Contraction

Figure 6.7a–b

Page 11: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Effect of Exercise on Muscles

Exercise increases muscle size (by increasing muscle fiber size, NOT increasing # of muscle fibers), strength, and endurance

Aerobic (endurance) exercise (biking, jogging) results in stronger, more flexible muscles with greater resistance to fatigue

Makes body metabolism more efficient

Improves digestion, coordination

Resistance (isometric) exercise (weight lifting) increases muscle size and strength

Page 12: CVA A&P - Chapter 6b: Muscle Contraction

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Effect of Exercise on Muscles

Figure 6.11