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Essentials of Anatomy & Physiology, 4th Edition Martini / Bartholomew PowerPoint ® Lecture Outlines prepared by Alan Magid, Duke University The Muscular.

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Presentation on theme: "Essentials of Anatomy & Physiology, 4th Edition Martini / Bartholomew PowerPoint ® Lecture Outlines prepared by Alan Magid, Duke University The Muscular."— Presentation transcript:

1 Essentials of Anatomy & Physiology, 4th Edition Martini / Bartholomew PowerPoint ® Lecture Outlines prepared by Alan Magid, Duke University The Muscular System The Muscular System 7 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Slides 1 to 110 A

2 Overview of Muscular System Types of Muscle Tissue Under voluntary control Skeletal muscles Attach to the skeleton The muscular system Under involuntary control Cardiac muscle Heart wall Smooth muscle Visceral organs Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

3 Overview of Muscular System Skeletal muscles Perform four functions Produce movement of skeleton (“dynamic”) Maintain posture, balance & body position (“static”) Guard “entrances” (mouth) and “exits” (anus) oral sphincter & anal sphincter Maintain body temperature (ex: shivering) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

4 Anatomy of Skeletal Muscles Gross (can see with “naked eye”) Anatomy Connective tissue organization Epimysium Fibrous covering of whole muscle Perimysium Fibrous covering of fascicle Endomysium Fibrous covering of a single cell (a muscle fiber) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

5 Anatomy of Skeletal Muscles The Organization of a Skeletal Muscle Figure 7-1 Quiz on all of these!

6 Skeletal muscles attach to bones… directly by way of tendons (thick dense regular connective tissue “ropes” indirectly by way of aponeuroses (thin connective tissue (sheets”)

7 Stop Here! Your first quiz will cover only the material on the first 5 slides that precede this one.

8 Anatomy of Skeletal Muscles Microanatomy of a Muscle Fiber Sarcolemma Muscle cell membrane Sarcoplasm Muscle cell cytoplasm Sarcoplasmic reticulum (SR) Like smooth ER Transverse tubules (T tubules) Myofibrils (contraction organelle) Sarcomeres Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

9 Anatomy of Skeletal Muscles Sarcomere—Repeating structural unit of the myofibril Components of a sarcomere Myofilaments Thin filaments (mostly actin) Thick filaments (mostly myosin) Z lines at each end Anchor for thin filaments Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

10 Anatomy of Skeletal Muscles The Organization of a Single Muscle Fiber Figure 7-2(a)

11 Anatomy of Skeletal Muscles The Organization of a Single Muscle Fiber Figure 7-2(b)

12 Anatomy of Skeletal Muscles The Organization of a Single Muscle Fiber Figure 7-2(cde) Anatomy of Skeletal Muscles PLAY

13 Anatomy of Skeletal Muscles Changes in the Appearance of a Sarcomere During Contraction of a Skeletal Muscle Fiber Figure 7-3 (1 of 2)

14 Anatomy of Skeletal Muscles Changes in the Appearance of a Sarcomere During Contraction of a Skeletal Muscle Fiber Figure 7-3 (2 of 2)

15 Control of Muscle Contraction Steps in Neuromuscular Transmission Motor neuron action potential Acetylcholine release and binding Action potential in sarcolemma T tubule action potential Calcium release from SR Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

16 Control of Muscle Contraction The Neuromuscular Junction Synaptic terminal Acetylcholine release Synaptic cleft Motor end plate Acetylcholine receptors Acetylcholine binding Acetylcholinesterase Acetylcholine removal Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

17 Control of Muscle Contraction The Structure and Function of the Neuromuscular Junction Figure 7-4(a)

18 Figure 7-4(b-c) 1 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Synaptic cleft Vesicles in the synaptic terminal fuse with the neuronal membrane and dump their contents into the synaptic cleft. The binding of ACh to the receptors increases the membrane permeability to sodium ions. Sodium ions then rush into the cell. An action potential spreads across the surface of the sarcolemma. While this occurs, AChE removes the ACh. Appearance of an action potential in the sarcolemma ACh binding at the motor and plate Release of acetylcholine Arrival of an action potential at the synaptic terminal Sarcolemma of motor end plate Arriving action potential Vesicles ACh AChE molecules ACh receptor site Action potential Synaptic terminal Axon Sarcolemma Muscle fiber Action potential Na +

19 Anatomy of Skeletal Muscles The Contraction Process Actin active sites and myosin cross-bridges interact Thin filaments slide past thick filaments Cross-bridges undergo a cycle of movement Attach, pivot, detach, return Troponin-tropomyosin control interaction Prevent interaction at rest Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

20 Figure of 7 Resting sarcomere Myosin head Myosin reactivation Active-site exposure Cross bridge detachment Cross-bridge formation Pivoting of myosin head Troponin Actin Tropomyosin ADP P + P + P + Active site Sarcoplasm Ca 2+ ADP P + + P Ca 2+ ADP + P Ca 2+ ADP + P Ca 2+ ADP + P Ca 2+ ATP Ca 2+ ADP P + + P

21 Control of Muscle Contraction Table 7-1 Summary of Contraction Process

22 Control of Muscle Contraction Key Note Skeletal muscle fibers shorten as thin filaments interact with thick filaments and sliding occurs. The trigger for contraction is the calcium ions released by the SR when the muscle fiber is stimulated by its motor neuron. Contraction is an active process; relaxation and the return to resting length is entirely passive. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings


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