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Overview of Muscle Tissue & How it Contracts Anatomy & Physiology.

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Presentation on theme: "Overview of Muscle Tissue & How it Contracts Anatomy & Physiology."— Presentation transcript:

1 Overview of Muscle Tissue & How it Contracts Anatomy & Physiology

2 Muscle Tissue: Comparisons Skeletal ▫attached to bones or skin ▫cells singular, very long, cylindrical, multinucleated ▫voluntary ▫striated ▫contractions slow to fast

3 Skeletal Muscle Fibers

4 Muscle Tissue:Comparisons Cardiac: ▫walls of the heart ▫branching chains of cells connected by intercalated discs, ▫uninucleated & striated ▫involuntary: pacemaker & nervous system control ▫slow contraction, rhythmic

5 Cardiac Muscle

6 Muscle Tissue: Comparisons Smooth: ▫walls of hollow viscera (except heart) ▫cells singular, fusiform ▫uninucleated, no striations ▫involuntary, controlled by nervous system, hormones, some chemicals, & stretch ▫contractions slow

7 Smooth Muscle Fibers

8 Muscle Fibers all skeletal muscle cells referred to as fibers all 3 muscle tissue type contract because of same 2 microfilaments: actin & myosin all have subunits with prefixes: myo- or sarco-

9 Connective Tissue Wrappings of Skeletal Muscle

10 Smooth Muscle Layers in GI Tract: Circular Inner/ Longitudinal Outer

11 Muscle Functions 1.Movement 2.Posture /Balance 3.Stabilizing Joints 4.Generating Heat

12 Skeletal Muscle Microanatomy Sarcolemma: plasma membrane Sarcoplasma: cytoplasm Myofilaments: actin or myosin Myosin: 1 of 2 principle contractile proteins Actin: 2 nd principle contractile protein Sarcoplasmic Reticulum: SER T-Tubules: ordered invaginations of sacroplasmic reticulum into sarcoplasma


14 Skeletal Muscle Properties 1.Irritability ▫ability to receive & respond to stimuli 2.Contractility ▫ability to forcibly shorten when adequate stimulus received

15 Nerve Stimulus 1 motor neuron (nerve cell that innervates a muscle fiber) may stimulate a few fibers or hundreds of them motor unit: 1 motor neuron & all the muscle fibers it stimulates

16 Nerve Stimulus axon: extension from cell body that carries the nerve impulse (action potential) to wherever neuron needs to send it axon terminal: end of axon

17 Neuromuscular Junction junction between axon terminals surface of muscle fiber Synapse: (synaptic cleft) gap filled with interstitial fluid

18 NMJ neurotransmitter : chemical (messenger molecule) released from axon terminal synaptic vesicles: vesicles that store neurotransmitter molecules in axon bulb until action potential hits which causes vesicle  exocytose acetylcholine: neurotransmitter in all motor neurons motor end plate: portion of sarcolemma that has receptor proteins for acetylcholine


20 Neuromuscular Junction

21 http://highered.mcgraw- pter10/animation__function_of_the_neuromus cular_junction__quiz_3_.htmlhttp://highered.mcgraw- pter10/animation__function_of_the_neuromus cular_junction__quiz_3_.html http://www.wisc- 04http://www.wisc- 04 /201_content/topicdir/muscle/muscle_media/ muscle_VD/page142/page142.html /201_content/topicdir/muscle/muscle_media/ muscle_VD/page142/page142.html

22 Mechanisms of Muscle Contraction

23 Sliding Filaments Animation _gif.html _gif.html /myosin.html /myosin.html


25 Muscle Movements Origin: muscle attachment to the immovable or less movable bone Insertion: muscle attachment to the movable bone

26 Flexion generally in sagittal plane decreases the angle of the joint & brings 2 bones closer together Hinge Joints Ball-and-Socket Joints

27 Extension movement that increases the distance between 2 bones or parts of the body If > 180 ◦ it is hyperextension

28 Rotation movement of a bone around its longitudinal axis Ball-and-Socket Joints Atlas/Dens (shaking head “no”)

29 Abduction moving a limb away fro the midline, or median plane includes fanning fingers or toes

30 Adduction movement of a limb toward midline

31 Circumduction proximal end stationary distal end moves in a circle limb as a whole outlines a cone

32 Dorsiflexion lifting foot so the dorsum of the foot (top of foot) approaches the shin corresponds to extension of the hand

33 Plantar Flexion depressing the foot ( pointing the toes) corresponds to flexion of the hand

34 Inversion of the Foot turn sole medially

35 Eversion of the Foot turn sole laterally

36 Supination “turning backward” forearm rotates laterally so palm faces anteriorly radius &ulna are parallel

37 Pronation “turning forward” forearm rotates medially so palm faces posteriorly radius crosses ulna

38 Opposition thumb touches tips of other fingers on same hand


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