Student%20Lecture%205%20%28Skeletal%20Muscle%20-%20Structure%20and%20Function%29

Student%20Lecture%205%20%28Skeletal%20Muscle%20-%20Structure%20and%20Function%29

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Unformatted text preview: Lecture 5 Skeletal Muscle Skeletal Structure and Function Tuesday 1­26­10 Outline Outline Announcements – Grant assignment #1 – Abstracts attached to assignment Extra Credit – Friday, January 29 – Dr. Jesse Witt – Assistant Professor – Psychological Sciences – Performance affects perception: Evidence form size, shape, and speed judgments – LAMB 108, 1:30 P.M. Quiz #3 Overview Lecture Skeletal Muscle Overview Skeletal Muscle Anatomy Overview Tendon Muscle – Attaches muscle to bone. – ________ surrounds muscle – _________ surrounds fasicle – __________ surrounds fasicle Fascicle Muscle fibers Myofibrils Sarcomeres ________ – Actin – ______ Fig 8.1 Muscle Muscle Over 400 skeletal muscles in human body _________________ _____ Length and diameter vary. Sartorius longest Human Anatomy Fascicle Number of muscle fibers per fascicle ______ Diameter _________ Exercise Physiology, Brooks, Fahey and Baldwin missinglink.ucsf.edu Muscle Fiber Muscle Cross­sectional area 1000­ 7000μm2 External lamina Multinucleated _____________ Sarcolemma Mitochondria – Produce myocytes – Produce nuclei – __________ Transverse Tubules ____________________ Myofibrils – Ca++ Exercise Physiology, McArdle, Katch, and Katch – Signal transduction via depolarization – Contractile machinery Myofibrils Myofibrils Cross­sectional area = _______ Sarcomeres – ________________ contained in a 10cm myofibril – Contractile unit Fig 8.2 Sarcomere Sarcomere Length 2.5μm Contractile Proteins Structural Proteins α­actinin – ______ “thin filament” – _______ “thick filament – Titin _______________________ __ Myosin to z line Holds myosin in proper horizontal orientation Exercise Physiology, Brooks, Fahey and Baldwin – M­line protein – ________________________ ________ Sarcomere (cont.) Sarcomere Z­line or Z­disk I­Band – Anchor point for actin filament – __________________ _____ – Myosin – __________________ ___________ Fig 8.5 A­Band H­zone Actin “thin filament” Actin _______________ – F­actin helix Made up of G­actin (actin monomers) _______________ – Tropomyosin – ______________ Covers myosin binding sites T­ binds to tropomyosin C­ binds Ca++ I­ regulates position of tropomyosin Exercise Physiology, Brooks, Fahey and Baldwin Myosin “thick filament” Myosin _______________ (MW 16­18 kd) – Connecting point for other light chain myosin _________________ ______ (200 kd) – A variety of isoforms – ________ Actin binding site ATpase Orientation of actin and myosin Orientation Actin forms a network that surrounds myosin Actin:Myosin _______ Myosin heads are oriented __________ around myosin protein Exercise Physiology, Brooks, Fahey and Baldwin Exercise Physiology, McArdle, Katch, and Katch Exercise Physiology, McArdle, Katch, and Katch Sliding Filament Theory Sliding Contraction – Myosin fixed – Actin moves inward _________________ _____________ Length of A band is maintained H and I bands become ________ Fig 8.5 Fiber Types Fiber All fibers are “not” created equal Factors within the fiber and outside the fiber contribute to fiber type Slow Fibers ________ Fibers – ________ – Type IIx – ________ – _________ Type I Type IIx Type IIa Fig 8.11 Classification of Fiber Types Classification Velocity of contraction _________________ _______ Fatigue resistance Sarcoplasmic reticulum proteins _________________ _____________ Morphometric related properties Substrate related properties _________________ _______ Blood flow related properties ACSM’s Advanced Exercise Physiology Type I Type ______ capillary density _______ myoglobin concentrations _______ mitochondria ______ resistance to fatigue Aerobic is predominant energy source ______ATPase activity _______ velocity _______ efficiency _______ force generation Table 8.1 Type IIa Type ______ capillary density _______ myoglobin concentrations _________ mitochondria ___________ resistance to fatigue Combination of aerobic and anaerobic are utilized as energy sources ______ ATPase activity ________ velocity _________ efficiency __________ force generation Table 8.1 Type IIx Type Low capillary density Low _________concentrations Low mitochondria Low resistance to fatigue Predominantly uses __________energy source Highest ____________ Highest velocity Low efficiency ___________________ Table 8.1 Determining muscle fiber type Determining Collect sample using muscle biopsy techniques Exercise Physiology, McArdle, Katch, and Katch Histology Histology Fix tissue Slice and place on slide Apply ________ to stain proteins of interest Gel electrophoresis Gel Western blot (protein) Run protein through agarose gel using electrical current Measure intensity of bands that form at the molecular weight of the protein of interest. Overview of muscle contraction Overview Motor neuron ________________ T­tubule Sarcoplasmic reticulum _____________________ _____ Relaxation Exercise Physiology, McArdle, Katch & Katch Motor Neuron Motor Transmit electrical signals from spinal cord to muscle fibers. ____________________ ____________________ ___________. A motor neuron and all muscle fibers it innervates is known as motor unit. Exercise Physiology, Brooks, Fahey & Baldwin Exercise Physiology, McArdle, Katch & Katch Motor Neuron Motor Axon Presynaptic Terminal – _____________ – ___________________________________ Exercise Physiology, McArdle, Katch & Katch Neuromuscular Junction Neuromuscular Action potential Release of _________ into neuromuscular cleft ACh binds to muscarinic receptors located on postsynaptic membrane ________________________ Signal: electrical → _________ →electrical Exercise Physiology, Brooks, Fahey & Baldwin Neuromuscular Junction Neuromuscular ACh is degraded by __________________ rapidly (5ms) End products of acetylcholinesterase (_________________) taken up by motor neuron to be resynthesized into ACh. Exercise Physiology, Brooks, Fahey & Baldwin ...
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