1. Chapter 10 Muscle Tissue and Organization 1

2. Skeletal muscles are voluntary muscles because they can be moved voluntarily Heart and digestive muscles contract on their own Muscles

3. Functions: –Body movement –Maintenance of posture –Temperature regulation (especially shivering when you are cold) –Storage and movement of materials control of openings (sphincters) to gastrointestinal and urinary tracts –Support abdominal cavity floor of pelvic cavity Muscles

4. Table 10.1a Copyright © McGraw-Hill Education. Permission required for reproduction or display. Muscle Fascicle Muscles made up of fascicles –groups of muscle cells

5. Table 10.1a Copyright © McGraw-Hill Education. Permission required for reproduction or display. Muscle Muscle fiber Fascicle Muscle cells are called muscle fibers Muscle fibers contain protein strands called myofibrils Myofibril

6. Table 10.1a Copyright © McGraw-Hill Education. Permission required for reproduction or display. Muscle fiber Fascicle Myofibrils made up of proteins called myofilaments Myofibril Thin filament Actin molecules Thick filament Heads of myosin molecules

7. Fig. 10.1 Tendon Deep fascia Skeletal muscle Tendons attach muscles to bones Deep fascia covers muscle –dense irregular connective tissue –separates individual muscles –binds muscles with similar function –helps distribute nerves and blood vessels –fills spaces between muscles –sits deep to superficial fascia (aka subcutaneous layer)

8. Fig. 10.1 Epimysium (a) Muscle Tendon Deep fascia Skeletal muscle Epimysium surrounds whole muscle (deep to deep fascia)

9. Fig. 10.1 Epimysium Perimysium Fascicle (a) Muscle Tendon Deep fascia Skeletal muscle Perimysium surrounds each fascicle –dense irregular connective tissue –contains neurovascular bundles (b) Fascicle Nuclei Artery Perimysium Muscle fiber Nerve Vein

10. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig. 10.1 Endomysium Fascicle Muscle fiber (a) Muscle Endomysium surrounds each muscle fiber –areolar connective tissue –insulates each fiber from electrical charge of other fibers (each can contract individually) –contains reticular fibers that bind neighboring muscle fibers together

11. Table 10.1c Endomysium Myofibril NucleiStriations Muscle fiber (c) Muscle fiber Sarcoplasm Sarcolemma (plasma membrane) Satellite cell

12. Fig. 10.4 Satellite cell Myoblasts Myoblasts fuse to form a skeletal muscle fiber Muscle fiber Satellite cell Muscle fibers derive from myoblasts in embryo Multiple myoblasts fuse into single cell with multiple nuclei Satellite cells are myoblasts that didn’t fuse –assist in repair if muscle injured

13. Fig. 10.3 Sarcolemma Sarcoplasm Mitochondria Myofilaments Myofibrils Nucleus Sarcoplasmic reticulum Transverse (T) tubule Terminal cisternae Plasma membrane of muscle cell = sarcolemma (sarco = flesh) Cytoplasm = sarcoplasm Sarcoplasmic reticulum stores calcium ions needed for muscle contraction –Parts of SR extend deeper across cell, called transverse tubules

14. Table 10.1d Sarcomere Myofibril Myofilaments Muscles move when myofilaments “walk” past each other Myofibril shortens, contracting muscles Muscles don’t “push”; They always pull Thin filament Actin molecules Thick filament Heads of myosin molecules

15. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig. 10.6 A bandI band Z disc (a) Z disc M line Z disc Thin filaments Connectin and accessory proteins I band Thin filaments Connectin A band Thick filaments Thin filaments M line Thick filaments and accessory proteins H zone Thick filaments (b) I band A band I band H zone Z disc Sarcomere (c) I band A band I band Connectin Z disc Thick filament M line Thin filament Z disc Sarcomere TEM 400x (d) Transverse sectional plane Sarcomere M line Myofilaments Myofibril Muscle fiber Sarcomeres I band Z disc H zone d: © James Dennis/Phototake Thin filament Sections of fibers create striations (stripes) in muscle tissue

16. Fig. 10.7 Copyright © McGraw-Hill Education. Permission required for reproduction or display. I band H zone Thin filament M line Connectin Z disc H zone Z disc H zone Z disc H zone I bandA band M line I band M line A band Sarcomere Thick filament (a) Relaxed muscle Sarcomere, I band, and H zone at a relaxed length. A band Sarcomere Z disc M line Z disc H zone Z disc H zone Z disc (b) Partially contracted muscle Thick and thin filaments start to slide past one another. The sarcomere, I band, and H zone are narrower and shorter. I bandA band M line Sarcomere I band Sarcomere M line A band I band Sarcomere M line Z disc (c) Fully contracted muscle The H zone and I band disappear, and the sarcomere is at its shortest length. Remember the lengths of the thick and thin filaments do not change. Z disc A band Z discA band M line Sarcomere M line A band Sarcomere a-c: © Dr. H.E. Huxley I band Z disc I band A band Z disc I band As muscles contract, striations change size https://www.youtube.co m/watch?v=Cjx3vSm54 N8

17. Fig. 10.10 Spinal cord Motor neuron 1 Muscle fibers innervated by motor neuron 1 Neuromuscular junctions Motor neuron 2 Motor unit is a motor neuron and all the muscle fibers it controls One motor unit controls some fibers in a muscle Smaller motor units provide finer control (ex. eye muscles)

18. Fig. 10.10 Spinal cord Motor neuron 1 Muscle fibers innervated by motor neuron 1 Neuromuscular junctions Motor neuron 2 all-or-none principle means fibers contract completely or not at all –Force exerted depends on number of motor units activated

19. Fig. 10.8 Neuromuscular junction Axon of a motor neuron Synaptic knob Skeletal muscle fiber LM 500x

20. Fig. 10.8 Path of nerve impulse Synaptic knob Endomysium Synaptic cleft Synaptic knob Motor end plate Synaptic vesicles Sarcolemma Sarcoplasm Acetylcholine (ACh) ACh receptor Sarcolemma Acetylcholinesterase (AChE) Neuromuscular junction Axon of a motor neuron Synaptic knob Skeletal muscle fiber

21. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig. 10.2 Tendon At end of muscle, connective tissue layers merge to form tendon –attaches muscle to bone, skin, or another muscle thin, flattened sheet of tendon is called aponeurosis Muscle attachment

22. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig. 10.2 Less mobile point of attachment of muscle is origin More mobile point of attachment is insertion Insertion usually moves toward origin In limbs, origin is proximal to insertion Muscle attachment Relaxed muscle Origin Contracted muscle Movement of insertion of muscle Insertion Tendon

23. Actions of Skeletal Muscles Agonist is a muscle that contracts to produce a particular movement Antagonist is a muscle whose actions oppose agonist –ex. agonist extends; antagonist flexes Synergist assists the agonist –stabilizes point of origin or contributes to tension at point of insertion –ex. biceps brachii and brachialis muscles

24. Naming of Skeletal Muscles Muscle action –Some names reflect function or movement of muscle -flexor -extensor -pronator Specific body region –anterior, posterior –superficialis or externus are visible from body surface –profundus or internus are deeper or more internal

25. Naming of Skeletal Muscles Muscle attachment –Named for origin, insertion, or prominent attachment –first part of name indicates origin and second part indicates insertion –ex. sternocleidomastoid originates on sternum and clavicle and inserts on mastoid Orientation of muscle fibers –rectus = straight –oblique = oblique angle to longitudinal axis of body

26. Naming of Skeletal Muscles Shape and size –deltoid = shaped like a triangle (delta, Δ) –orbicularis = shaped like a circle (orbit) –trapezius = shaped like a trapezoid –brevis = short –longus or longissimus = long –teres = long and round

27. Naming of Skeletal Muscles Shape and size –magnus = large, big –major = bigger –maximus = biggest –minor = small –minimus = smallest

28. Naming of Skeletal Muscles Heads/tendons of origin –biceps = two tendons of origin –triceps = three tendons of origin –quadriceps = four tendons of origin ex. quadriceps femoris = thigh muscle with four heads/tendons of origin

29. Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig. 10.15 Intercalated discs Endomysium Gap junctions Desmosomes (b) MitochondrionSarcolemmaNucleus Cardiac muscle cell A band I band Intercalated disc Centrally located nucleus Cardiac muscle cell (cardiocyte) Endomysium Z discs (a) Cardiac muscle Striated; bands visible under microscope One nucleus per cell Autorhythmic: individual cells can generate contractions by themselves

30. Cardiac Muscle Intercalated discs

31. Fig. 10.16 Smooth muscle Not striated; each cell tapered at each end Contractions slow, resistant to fatigue Present in gut, blood vessel walls, etc.; under involuntary control