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POWERPOINT ® LECTURE SLIDE PRESENTATION by LYNN CIALDELLA, MA, MBA, The University of Texas at Austin Additional Material by J. Padilla exclusively for.

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Presentation on theme: "POWERPOINT ® LECTURE SLIDE PRESENTATION by LYNN CIALDELLA, MA, MBA, The University of Texas at Austin Additional Material by J. Padilla exclusively for."— Presentation transcript:

1 POWERPOINT ® LECTURE SLIDE PRESENTATION by LYNN CIALDELLA, MA, MBA, The University of Texas at Austin Additional Material by J. Padilla exclusively for Physiology 31 at ECC Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings HUMAN PHYSIOLOGY AN INTEGRATED APPROACH FOURTH EDITION DEE UNGLAUB SILVERTHORN UNIT 2 PART A 12 Muscles

2 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Three Types of Muscle Figure 12-1a Cylindrical shaped, multinuclei, straited, voluntary, fibers of different speeds Branched, uni- /binuclei, involuntary, striated, rhythmic contractions Spindled shaped, one nucleus, involuntary, non-straited, internal organs Cylindrical shaped, multinuclei, straited, voluntary, fibers of different speeds Branched, uni- /binuclei, involuntary, striated, rhythmic contractions Spindled shaped, one nucleus, involuntary, non-straited, internal organs

3 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Muscles: Summary

4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Skeletal Muscle  Usually attached to bones by tendons- sometimes attached directly to bone (pectoralis major)  Origin: closest to the trunk- usually does not move a joint when contracts.  Insertion: more distal- moves joint when contracts  Flexor: brings bones together- decreases angle at joint  Extensor: bones move away- increases angle at joint  Antagonistic muscle groups: flexor-extensor pairs- antagonistic muscles are usually in opposite sides.

5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-3a (1 of 2) Anatomy Summary: Skeletal Muscle

6 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy Review: Muscle Fiber Structure

7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-3b Ultrastructure of Muscle

8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy Summary: Skeletal Muscle Figure 12-3a (2 of 2)

9 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-3e Ultrastructure of Muscle Myosin are motor proteins. 250 myosins join to form the thick filaments. The thin filament is made up of a string of actin with tropomyosin and tropnin attached. Titin and nebulin anchor and stabilize.

10 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Ultrastructure of Muscle Figure 12-3c–f Myofibril A band Z disk I band M line H zone Z disk Sarcomere Thin filaments Tropomyosin Troponin Actin chain G-actin molecule Myosin tail Myosin heads Myosin molecule (c) (d) (e) Thick filaments Hinge region (f) Titin Nebulin Titin M line Actin and myosin form crossbridges

11 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-7 Summary of Muscle Contraction Muscle tension: force created by muscle Load: weight that opposes contraction Contraction: creation of tension in muscle Relaxation: release of tension Muscle tension: force created by muscle Load: weight that opposes contraction Contraction: creation of tension in muscle Relaxation: release of tension

12 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Neuromuscular Junction: Overview  Terminal boutons- insulate the site of the neuromuscular juction and secrete supportive growth factors  Synaptic cleft- space between the axon terminal and the sarcolemma  Acetylcholine- neurotransmitter released involves calcium and binds to nicotinic receptors  Motor end plate- folds on the sarcolemma of the muscle  On muscle cell surface  Nicotinic receptors

13 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure (1 of 3) Anatomy of the Neuromuscular Junction

14 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Neuromuscular Junction Figure (2 of 3)

15 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Neuromuscular Junction Figure (3 of 3)

16 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Mechanism of Signal Conduction  Axon terminal (of presynaptic cell)  Action potential signals acetylcholine release  Motor end plate – series of folds in the plasma membrane of the postsynaptic cell  Two acetylcholine bind  Opens cation channel  Na + influx – K+ efflux  Membrane depolarized  Stimulates fiber contraction as a result in increased intracellular calcium concentration

17 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 11-13a Events at the Neuromuscular Junction

18 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-4 T-tubules and the Sarcoplasmic Reticulum

19 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-11a, step 1 Excitation-Contraction Coupling Muscle fiber Motor end plate ACh Axon terminal of somatic motor neuron Sarcoplasmic reticulum Actin Troponin Tropomyosin Myosin head Z disk Myosin thick filament M line T-tubule DHP receptor Ca 2+ Somatic motor neuron releases ACh at neuro- muscular junction. (a) 1 1

20 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-11a, steps 1–2 Excitation-Contraction Coupling Muscle fiber Motor end plate ACh Axon terminal of somatic motor neuron Sarcoplasmic reticulum Actin Troponin Tropomyosin Myosin head Z disk Myosin thick filament M line T-tubule DHP receptor Ca 2+ Somatic motor neuron releases ACh at neuro- muscular junction. Net entry of Na + through ACh receptor-channel initiates a muscle action potential. Na + K+K+ (a) potential 1 Action Action potential

21 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-11b Excitation-Contraction Coupling Animation: Muscular System: The Neuromuscular Junction PLAY M line Ca 2+ Distance actin moves Ca 2+ released Myosin thick filament (b) Action potential in t-tubule alters conformation of DHP receptor. DHP receptor opens Ca 2+ release channels in sarcoplasmic reticulum and Ca 2+ enters cytoplasm. Ca 2+ binds to troponin, allowing strong actin- myosin binding. Myosin heads execute power stroke. Actin filament slides toward center of sarcomere

22 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-8 Changes in Sarcomere Length during Contraction Animation: Muscular System: Sliding Filament Theory PLAY

23 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-10a Regulatory Role of Tropomyosin and Troponin In the relaxed state the myosin head is at 90o but it is unbound to actin because the binding sites on actin are blocked.

24 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-10b Regulatory Role of Tropomyosin and Troponin** PiPi ADP G-actin moves Cytosolic Ca 2+ Tropomyosin shifts, exposing binding site on G-actin TN Power stroke Initiation of contraction Ca 2+ levels increase in cytosol. Ca 2+ binds to troponin. Troponin-Ca 2+ complex pulls tropomyosin away from G-actin binding site. Myosin binds to actin and completes power stroke. Actin filament moves. (b)

25 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-9, steps 1–2 The Molecular Basis of Contraction ATP binding site Myosin binding sites Tight binding in the rigor state. The crossbridge is at a 45° angle relative to the filaments. Myosin filament 45° G-actin molecule ATP binds to its binding site on the myosin. Myosin then dissociates from actin. ATP

26 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-9, steps 3–4 The Molecular Basis of Contraction The ATPase activity of myosin hydrolyzes the ATP. ADP and P i remain bound to myosin. The myosin head swings over and binds weakly to a new actin molecule. The cross- bridge is now at 90º relative to the filaments. PiPi PiPi ADP 90°

27 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-9, steps 5–6 The Molecular Basis of Contraction At the end of the power stroke, the myosin head releases ADP and resumes the tightly bound rigor state. ADP Release of P i initiates the power stroke. The myosin head rotates on its hinge, pushing the actin filament past it. PiPi Actin filament moves toward M line

28 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12-9 The Molecular Basis of Contraction At the end of the power stroke, the myosin head releases ADP and resumes the tightly bound rigor state. ATP binding site ADP Tight binding in the rigor state. The crossbridge is at a 45° angle relative to the filaments. Myosin filament 45° G-actin molecule ATP binds to its binding site on the myosin. Myosin then dissociates from actin. The ATPase activity of myosin hydrolyzes the ATP. ADP and P i remain bound to myosin. ATP The myosin head swings over and binds weakly to a new actin molecule. The crossbridge is now at 90º relative to the filaments. PiPi PiPi ADP 90° Release of P i initiates the power stroke. The myosin head rotates on its hinge, pushing the actin filament past it. PiPi Actin filament moves toward M line. Contraction- relaxation Sliding filament Myosin binding sites

29 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Fatigue: Multiple Causes  Extended submaximal exercise  Depletion of glycogen stores  Short-duration maximal exertion  Increased levels of inorganic phosphate  May slow P i release from myosin  Decrease calcium release  Potassium is another factor in fatigue

30 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Length-Tension Relationships in Contracting Muscle Figure The strength of the contraction is related to the length before the muscle contracts. Very short fibers do not produce much tension because there is a lot of overlap not allowing for much sliding and not many new crossbridges. At optimum lenght there is an optimum number of cross-bridges to there is optimum tension. At a longer length there is less overlap and less ability to produce optimal force

31 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure Electrical and Mechanical Events in Muscle Contraction A twitch is a single contraction-relaxation cycle

32 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Summation of Contractions Figure 12-17a Stimuli is too far apart and allows the muscle to relax and lose tension If action potentials come in at a closer time they recruit more fibers and the additive effect results in increased muscle tension Stimuli is too far apart and allows the muscle to relax and lose tension If action potentials come in at a closer time they recruit more fibers and the additive effect results in increased muscle tension

33 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Summation of Contractions Figure 12-17c The more stimulus the more fibers recruited until there is a maximum tension but is there is alot of time between the stimulus the muscle relaxes resulting in an unfused tetanus

34 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Summation of Contractions Figure 12-17d Complete tetanus results when action potentials arrive close enough to not allow the muscle to relax. Maximum tension can only be sustained for a limited time because fatigue

35 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Motor Units: Fine motor movements have more innervations

36 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Mechanics of Body Movement  Isotonic contractions create force and move load- creates force and moves a load.  Concentric action is a shortening action- contraction that flexes the joint while working against a load  Eccentric action is a lengthening action- contraction that extends the joint while resisting a load  Isometric contractions create force without moving a load- the muscle produces tension and contracts but does not move the joint.

37 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure Isotonic and Isometric Contractions

38 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure Muscle Contraction Duration of muscle contraction of the three types of muscle- in smooth muscle contraction and relaxation happen slower and can be sustained for a longer time.

39 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle: Properties  Uses less energy- can maintain maximum tension while using only a small percentage of the total maximum cross bridge  Maintain force for long periods- allows organs to be tonically contracted and maintain tension for a long time (sphincter muscles)  Low oxygen consumption- allows for to maintain tension for a long time without fatiguing (bladder).

40 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle  Smooth muscle is not studied as much as skeletal muscle because  It has more variety- impossible to come up with a single muscle function model- special types for vascular, gastrointestinal, urinary, respiratory, reproductive, and ocular  Anatomy makes functional studies difficult- fibers within cells and muscle layers within organs run indifferent directions.  It is controlled by hormones, paracrines, and neurotransmitters  It has variable electrical properties- contraction is not triggered only action potential  Multiple pathways influence contraction and relaxation- acts as an integrating center to interpret mutiple excitatory and inhibitory signals that may arrive at the same time

41 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings  IV. Smooth Muscle- A tissue formed by uninucleated spindle shaped cells found in six areas of the body: blood vessel walls, respiratory tract, digestive tubes, urinary organs, reproductive organs, and the eye. Smooth Muscle Locations

42 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle layer orientations

43 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Cellular details of smooth muscle

44 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Disorders  Muscle cramp: sustained painful contraction – hyperexcitability of the motor unit, countered with stretching  Overuse – excessive use that causes tearing in the muscle structures (fibers, sheaths, tendon connection)  Disuse- loss of muscle activity causes muscle atrophy because of loss of blood flow, can recover is disuse is less than a year  Acquired disorders – infectious diseases and toxin poisoning that lead to muscle weakness or paralysis  Inherited disorders -  Duchenne’s muscular dystrophy – muscle degenrates from pelvis up, happens most often in women, people live to be , die of respiratory failure  Dystrophin –links actin to proteins in cell membrane  McArdle’s disease – limited exercise tolerance  Glycogen to glucose-6-phosphate – enzyme missing thus muscles do not have the energy source available.


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