A&P I Muscle notes
A&P I Muscle notes BIOL 2500 - 018
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This 5 page Class Notes was uploaded by Margaret Notetaker on Sunday October 4, 2015. The Class Notes belongs to BIOL 2500 - 018 at Auburn University taught by Shobnom Ferdous in Fall 2015. Since its upload, it has received 72 views. For similar materials see Human Anatomy and Physiology I in Biology at Auburn University.
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Date Created: 10/04/15
CHAPTER 9 amp 10 MUSCULAR SYSTEM Characteristics 1 Excitability a Can receive amp respond to stimuli 2 Contractility a Can shorten when stimulated 3 Extensibility a Stretches 4 Elasticity a Can return to original shape Functions Movement Maintain posture Heat production Stabilize joints Gross Anatomy of Skeletal Muscle Nerves amp Blood Vessels Skeletal muscle bers innervated by nerve endings Highly vascularized for nutrients oxygen energy amp waster removal Connective Tissue Wrappings Epimysium o Surrounds the Whole muscle 0 Dense irregular connective tissue Perimysium o Surrounds each fascicle o Dense regular connective tissue Endomysium o Surrounds each muscle ber 0 Areolar loose connective tissue Functions 0 Support muscle bers 0 Hold muscles together 0 Elasticity of muscle 0 Carries blood vessels amp nerve to muscle bers Attachments Direct epimysium periosteum or perichondrium Indirect via tendons or aponeuroses Origin 0 Point of attachment to immoveable bone Insertion 0 Point of attachment to moveable bone CHAPTER 9 amp 10 MUSCULAR SYSTEM Microscopic Anatomy of Skeletal Muscle Muscle Fiber Multinucleate Plasma membrane is called sarcolemma Cytoplasm is called sarcoplasm 0 Has usual organelles o Glycosomes are granules of stored glycogen o Myoglobin is red pigment that carries oxygen Sarcoplasmic reticulum 0 Smooth endoplasmic reticulum around myo brils 0 Store regulate release calcium Myo bril organelle Z line disc 0 Anchor for actin laments 0 Center of the 1 band M line 0 Anchor for myosin laments 0 Center of the H zone A band 0 Dark area 0 Extends the length of the myosin laments 1 band 0 Light area 0 Only has actin laments 0 Z line is the center 0 H zone 0 Only myosin laments o M line is the center Sarcomere 0 Functional unit 0 Measured Z disc to Z disc 0 Aligned end to end with myo bril Myo lament Myosin o Thicker myo laments o Rodlike tail amp 2 globular heads 0 Heads have binding sites for actin amp ATP Actin o Thinner myo laments 0 Made of Gactin I Polypeptide subunits I Has binding sites for myosin head I 2 strands twisted together Tropomyosin 0 Found in actin myo laments CHAPTER 9 amp 10 MUSCULAR SYSTEM 0 Rodshaped protein 0 Blocks myosinbinding sites on actin when muscle relaxed Troponin o In actin myofllaments o 3 polypeptide subunit complex I l bound to actin I l bound to tropomyosin I l bound to calcium Functional Groups Prime Movers Agonists Muscle provides primary force for causing speci c movement Ex biceps brachii for forearm exion Ex Triceps brachii for forearm extension Antagonists Opposes reverses steadies movement Opposite side of joint as prime mover Ex triceps brachii for forearm exion Synergists Assist prime movers Add extra force to same movement Prevent unwanted movement Ex wrist extensor prevent wrist bending when finger exors contract Fixators Synergists that immobilize bone or muscle s origin Ex muscles for upright posture Naming Skeletal Muscles Location Bonebody region associated with muscle Ex intercostals between ribs Shape Distinctive shape of muscle Ex deltoid triangle Size Relative size of muscle Maximus large Minimus small Direction of muscle fibers Transversus run at right angles Rectus straight Number of origins Bi 2 origins Tri 3 origins CHAPTER 9 amp 10 MUSCULAR SYSTEM Location of attachments Origin is named first Sternocleidomastoid 0 Origin sternum amp clavicle o Insertion mastoid process of temporal bone Action Movement of muscle Adductor adduction Arrangement of Fascicles Circular Arranged in concentric rings Orbicularis oris Convergent Converge towards a single tendon Pectoralis major Parallel Long axis of muscle run parallel to long axis of muscle Sartorius Fusiform Spindle shaped Biceps brachii Pennate Attach to central tendon at an angle Unipennate o Extensor digitorum longus Bipennate o Rectus femoris Multipennate o Deltoid Lever Systems Lever Rigid bar bone that moves about a xed point Fulcrum Fixed point joint Effort Force applied by muscle on the insertion point Load Resistance Bone itself associated tissue Mechanical Advantage Power levers Load is closer to fulcrum than effort applied Small effort can move large load CHAPTER 9 amp 10 MUSCULAR SYSTEM Mechanical Disadvantage Speed levers Load is farther from fulcrum than effort applied Effort must be greater than load First Class Lever Effort applied at one end of lever Load at the other end Fulcrum between effort amp load Operates at mechanical advantage amp disadvantage Effort Fulcrum Load Second Class Lever Effort applied at one end of lever Fulcrum at other end Load between effort amp fulcrum Mechanical advantage Effort Load Fulcrum Third Class Lever Load at one end of lever Fulcrum at other end Effort between load amp fulcrum Mechanical disadvantage Load Effort Fulcrum