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2  Over 600 muscles  45% of adult body weight  Bundles of muscle fibers held together by connective tissue  Nerve stimulation allows contraction  become short and thick  Contraction depends on myofilaments  actin and myosin

3 Allows the body to move walking Blinking, smiling Also aids in blood pressure regulation Posture Heat Generator Stabilization of joints Protection of some organs Control of peristaltic contractions used in the digestive system to move food

4 Excitability - receive and respond to a stimulus Contractibility- ability to become short and thick Extensibility- ability to be stretched Elasticity- ability to resume resting length after stretch Automaticity- can contract involuntarily

5 Three types 1.skeletal 2.smooth 3.cardiac Found throughout the body Functions vary based on type

6 Sometimes called striated muscle Are typically attached to bone by tendons, a tough connective “cord” Responsible for voluntary movements running smiling clapping your hands Agonist: initiates movement of muscle Antagonist: oppose or reverses movement

7 Methods of Attachment to Bone Tendon- muscle to bone Fascia- tough, sheet like Aponeurosis- broad, flat sheet Origin- end that does not move Insertion- end that moves when muscle contracts

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9 Involuntary control NOT striated Aids in Digestive/ Respiratory movement Located in: large and small intestine stomach blood vessels

10 Function to: push food through the digestive system controls blood flow through vessels Most can function in the absence of nervous stimulation Peristaltic contractions of smooth muscle move food through the digestive system

Cardio- comes from a Greek word meaning heart! 11 Located only in the heart Are striated muscles Controlled by the central nervous system

12 Muscle Tone- state of partial contraction Adduction- toward body Abduction- away from body Rotation- turning around an axis Flexion- decreasing angle, bending Extension- increasing angle, straightening Circumduction- circle around a joint Pronation- turning down Supination- turning up Dorsiflexion- bending foot up Plantar flexion- bending foot down Atrophy- when muscles are not used over a period of time/ they get smaller

13 Fibromyalgia- chronic musculoskeletal pain Muscular Dystrophy- inherited disease leading to chronic muscle atrophy Muscle Spasms- sudden involuntary muscle contraction Strain- overstretching or injury to a muscle or tendon

Medications Analgesic- relieves pain; Aspirin, Tylenol, and NSAIDS Anti-inflammatory- reduce inflammation; steroids, ibuprofen and NSAIDS decrease inflammation. Muscle relaxant- relieves stiffness; Flexeril, Robaxin. NSAIDS- Non-steroidal anti-inflammatory drugs; Ex.Naproxyn

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16 Is covered with a layer of connective tissue Nerves and blood vessels enter and exit muscles along this tissue Structural unit is the muscle fiber or myofiber do not typically extend the length of the muscle vary in diameter Myofibrils make up 75-92% of muscle volume!

17 Sarcolemma surrounds muscle fiber composed of lipid and proteins is elastic, which allows for muscle contraction and relaxation Myofibrils extend the length of the muscle fiber composed of myofilaments actin myosin Myofibril Sarcolemma Muscle fiber cross-section

18 Skeletal Muscle Muscle Bundles Myofibrils Muscle Fibers Sarcomeres

19 Several hundred to several thousand in one muscle fiber depending upon diameter Has striations, or further divisions called sarcomeres

20 Contain protein filaments actin- thin filament myosin- thick filament Z line is located at each end

21 Z line Actin Myosin A bandI band Relaxed Muscle

22 Occurs when thin filaments slide over thick filaments Formation of cross-bridge between myosin and actin must occur

23 Actin filament is pulled when the cross- bridge changes shape causes distance between Z lines to decrease

24 Detachment of actin from cross-bridge Is repeated after myosin-actin cross-bridge formation ATP provides energy needed for contraction and relaxation

25 Motor nerve arrives at motor end plate Acetylcholine, a neurotransmitter, is released by the motor neuron diffuses across the synapse, causing release of calcium ions allow actin and myosin filaments to form cross-bridge

26 Relaxation occurs when acetylcholine is no longer present cholinesterase is responsible for breakdown of remaining acetylcholine Calcium is removed and returned to sarcoplasmic reticulum Actin-myosin crossbridges are destroyed Sarcomeres return to resting position

7.What is the main difference between tendons and ligaments? 8.What are the three types of muscle tissue? 27

10. Which muscle types are striated? 11. Where can smooth muscle tissues be found? 12. Actin and myosin are ___________. 28