Chapter 10 Muscle Tissue Lecture Presentation by Lee

Chapter 10 Muscle Tissue Lecture Presentation by Lee Ann Frederick University of Texas at Arlington (heavily modified by GJC) © 2015 Pearson Education, Inc.

An Introduction to Muscle Tissue • Review (from Chapter 4): • What are the 3 types of muscle tissue and what are the differences among them?

10 -1 Functions of Skeletal Muscle Tissue • Functions of Skeletal Muscle Tissue

SKELETAL MUSCLE (organ) FASCICLE (bundle of fibers) MUSCLE FIBER (cell) 10 th Martini, Figure 10 -1 © 2015 Pearson Education, Inc.

Figure 10 -2 a The Formation of a Multinucleate Skeletal Muscle Fiber. Muscle fibers develop through the fusion of embryonic cells called myoblasts. Myoblast Myosatellite cell Immature muscle fiber Myosatellite cell Mature muscle fiber © 2015 Pearson Education, Inc.

Why (some) muscles look striated (striped) http: //en. wikipedia. org/wiki/Sarcomere

Figure 10 -5 Sarcomere Structure, Superficial and Cross-Sectional Views. Sarcomere © 2015 Pearson Education, Inc.

How muscles contract: a multi-step overview 1. A motor neuron transmits A-C-h; A-C-h opens sodium channels; 2. Sodium causes depolarization; Depolarization triggers the SR…. 3. And the SR releases calcium ions, And the calcium ions bind to troponin, 4. And troponin gives tropomyosin a tug, And tropomyosin accommodates myosin, 5. And myosin pulls on the actin, child -The myosin pulls on the actin.

http: //www. noteflight. com/scores/view/5 a 4 cd 6 a 620007 ba 4 b 24 b 5 e 15 d 5 c 58196 e 238927 a

The neuromuscular junction (Figure 10 -9) Arriving action potential Na+ 1 © 2015 Pearson Education, Inc. 2 Na+ ACh 3 receptor Na+

Figure 10 -10 Excitation-Contraction Coupling. © 2015 Pearson Education, Inc.

[Space to take notes on previous figure]

The contraction cycle (Figure 10 -11) 1 2 3 white ovals = ADP + Pi (breakdown products of ATP)

The contraction cycle (Figure 10 -11) 4 5 yellow ovals = ATP 6

Where in the contraction cycle will a “fresh” dead person’s muscles stop?

Figure 10 -12 Shortening during a Contraction. a When both ends are free to move, the ends of a contracting muscle fiber move toward the center of the muscle fiber. b When only one end of a myofibril is fixed in position, the free end is pulled toward the fixed end. © 2015 Pearson Education, Inc.

How does a muscle contraction END?

The effect of sarcomere length on muscle force (like Figure 10 -14) Figure: Principles of Physiology by Cindy L. Stanfield

Figure 10 -17 a The Arrangement and Activity of Motor Units in a Skeletal Muscle. Axons of motor neurons Motor nerve KEY Motor unit 1 Motor unit 2 Motor unit 3 © 2015 Pearson Education, Inc. SPINAL CORD Muscle fibers

How do we adjust a muscle’s level of force? (2 basic ways)

Figure 10 -18 Concentric, Eccentric, and Isometric Contractions. Tendon 2 kg 6 kg © 2015 Pearson Education, Inc.

Why are eccentric contractions clinically interesting?

Figure 10 -20 Muscle Metabolism. Fatty acids O 2 Glucose Glycogen ADP ATP Pyruvate ADP ATP CO 2 © 2015 Pearson Education, Inc. To myofibrils to support muscle contraction

3 key components of muscle Component Contractile proteins (actin/myosin) Sarcoplasmic Reticulum (SR) Mitochondria Function Effect of strength training endurance training

Changes in SR? Look at evolution… P. J. Schaeffer et al. , Journal of Experimental Biology (1996)