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MUSCLES. muscle/mustut.htm muscle/mustut.htm

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3 muscle/mustut.htm muscle/mustut.htm GrossAnatomy/dissector/mml/index.htm GrossAnatomy/dissector/mml/index.htm

4 THREE TYPES OF MUSCLES Cardiac Smooth Skeletal

5 PROPERTIES OF MUSCLES Ability to contract Extensibility – ability to be stretched Elasticity – ability to return it its original length Irritability – ability to receive and repord to stimuli

6 TERMS Myo – muscle Sacro - flesh Muscle fiber – individual muscle cell

7 SKELETAL MUSCLE Bundles of muscle fibers that are package to form the organ

8 CONNECTIVE TISSUE OF SKELETAL MUSCLE Warps or bundles up muscle fibers Provides support and strength to muscle Keeps muscles form being ripped apart under tremendous forces

9 PARTS OF MUSCLE FIBER Endomysium – connective tissue sheath that wraps each individual muscle fiber Perimysium – coarser fibrous membrane that surrounds several muscle fibers Fascicle – bundle of fibers Epimysium – tougher layer of connective tissue that covers many fascicles – covers entire muscle –


11 Epimysium

12 EPIMYSIUM Ends of it will blend into –Tendons –Aponeurosis – attaches muscles indirectly to bones, cartilage or connective tissue

13 TERMS Origin – muscle attaches to stationary bone Insertion – muscle attaches to bone that moves When muscle contracts, one bone moves and the other is stationary

14 MOVEMENT OF BODY PARTS Body part is moved by a group of muscles: –Prime mover –Synergists –fixators Antagonists - pairs that work opposite


16 Tendon- connective tissue that attaches muscle to bone –Very tough – thus is gives muscles durability –Does not wear out next to rough projections of bone –Usually tendon that passes over bony joint and not muscle

17 Muscles are arrange differently depending on where they are located


19 COMPONENTS OF SKELETAL MUSCLE Saroclemma Sarcoplasmic reticulum Sarcoplasm sarcomere

20 Parts of Sarcomere Myofibril (fibril) 0 complex organelle composed of bundles of myofilaments. Fill the cytoplasm of muscles. Myofilaments – threadlike filaments – has alternating light and dark bonds - composed of 2 key proteins –Actin –myosin


22 myosin Thick protein filament Contains ATPase – splits ATP to generate the energy needed for muscle contraction Extends the entire length of the dark A boand Midpart is smooth End are studded with projections called myosin heads or cross bridges

23 actin Thin filament Made up of contractile protein Actin is anchored to the Z line I band – 2 adjacent sarcomeres and contains only actin Actin does not extend into the middle of the A band which makes the H zone appear lighter

24 When contraction occurs – actin filament slide toward each other into the center of the sarcomeres Light zone disappears because actin and myosin totally overlap




28 Relaxed muscle has regulatory proteins on the actin to prevent myosin from bending

29 AP stimulates the sarcolemma of the muscle Ca ions are released from the sarcoplasmic reticulum Ca ions bind to the regulatory proteins on the actin This changes the shape and location of the regulatory proteins on the actin

30 Binding sites on the actin become exposes Myosin heads attach to the binding sites on the actin (called cross bridge formation) When heads attach, they snap toward center of sarcomere (power stroke) This pulls actin toward center of sarcomere ATP provides Energy to release and recock myosin heads


32 Cross bridge is broken Myosin head reattaches to another site further along the actin (another cross bridge and power stroke) This is called walking of the myosin AP ends Ca ions reabsorbed by sarcoplasmic reticulum

33 Regulatory proteins return to their original shape and position Myosin can’t attach Muscle relaxes

34 MACROSCOPIC CONTRACTION Muscle cell - all or none response Thousands of muscle cells form the organ Skeletal muscle’s response is graded – different degrees of contraction

35 2 WAYS TO PRODUCE GRADED REPONSE 1 - Changing the speed of muscle stimulation 2 - Changing the number of muscle cells stimulated

36 Pat vs. slap If few cells (motor units) are stimulated, then the contraction of the muscle is slight. As more cells are stimulated, the grater the contraction


38 All muscles cross at least 1 joint The bulk of the muscle lies proximal to the joint crossed. All muscles have at least 2 attachments Muscles can only pull, they never push During contraction muscle moves toward the origion

39 DISEASES Tetanus Muscular dystrophy Duchenne muscular dystrophy Problems associated with steroid use. What is the proper way to lift a heavy object?

40 Muscle twitch Bell’s palsy Inguinal hernia Muscle cramp

41 Pictures to label

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