FA23PSA7

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Indiana University, Purdue University, Indianapolis *

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103

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Mechanical Engineering

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Jan 9, 2024

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docx

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Pre-Session Assignment (PSA) #7 Name ______________________________________________ Complete the vocabulary-matching sections and at least the first three objectives for each chapter. Doing so will prepare you for recitations and for the quizzes. You are highly encouraged to complete the rest of the objectives to keep you on track and so you can ask for clarification during recitation. All answers can be found in the textbook, even if a section has not yet been covered in lecture. Please complete and turn in one hour before the designated weekly recitation time via canvas. Chapter 40 Objectives: Movement (Muscles) 1 __B_ thin myofilaments __I_ found in smooth muscle and is the point where actin is anchored __E_ a nerve axon and all of the muscle fibers it innervates __C_ a muscle that works with another in a particular movement __M_ a region in the center of the H zone and it is the proteins that hold the neighboring myosin filaments together __I_ runs length of myosin fiber (will contain actin and overlapping myosin) __J_ in a sarcomere it includes the Z line and the actin filaments up to the point where they overlap with the myosin filaments __D_ a muscle cell __P_ a muscle that opposes the movement of another muscle __N_ a cytoplasmic grouping of myofilaments __L_ plasma membrane of a muscle cell __Q_ thick myofilaments __R_ a region of the sarcomere that is only myosin only, it is the myosin between the actin filaments that overlap the ends of the myosin __T_ an individual contractile unit in skeletal muscle __O_ make up myofibrils and are either actin or myosin filaments __U_ located in skeletal muscle cells and is the region where the T tubule runs between parts of the sarcoplasmic reticulum creating a region of SR-T tubule-SR _S__ a protein complex located on tropomyosin, it contains a calcium binding site that regulates the interaction of actin and myosin by causing tropomyosin to role away from the myosin binding site on actin _Z__ inward extension of the sarcolemma membrane, it runs through the cell and is in contact with the sarcoplasmic reticulum _U__ the endoplasmic reticulum in a muscle cell _S__ at beginning and end of a sarcomere and the point where actin is anchored _R__ a protein chain that regulates the interaction of actin and myosin by covering the actin binding sites on myosin when calcium is absent and a muscle is not contracting A. A Band B. Actin C. Agonist D. Antagonist E. Dense Body F. H Zone G. I Band H. M Line I. Motor Unit J. Myofiber K. Myofibril L. Myofilament M. Myosin N. Sarcolemma O. Sarcomere P. Sarcoplasmic Reticulum Q. Triad R. Troponin S. Tropomyosin T. T Tubule U. Z Line

Chapter 40 Objectives: Movement (Muscles) 1. Describe the structural organization of skeletal muscle, a skeletal muscle cell, a sarcomere, and the structure and interaction of actin and myosin myofilaments (drawing helpful! ) Skeletal muscles consist of muscle cells (myofibers) that contain sarcomeres, the basic contractile units. Sarcomeres are defined by Z-lines and are composed of actin and myosin myofilaments. Muscle contraction occurs when myosin heads interact with actin, causing the sarcomere to shorten and resulting in muscle movement. 2. Describe events at a sarcomere as it contracts and relaxes and sketch and label a sarcomere in the relaxed and contracted state In a relaxed sarcomere, actin and myosin myofilaments are not fully overlapped. During contraction, signals from the nervous system stimulate myosin heads to bind with actin, causing the sarcomere to shorten. This interaction is powered by the hydrolysis of ATP and the sliding of myosin along actin filaments. When the contraction is complete, myosin heads release the actin, and the sarcomere returns to its relaxed state. A relaxed sarcomere appears longer with distinct actin and myosin regions, while a contracted sarcomere shows overlapping actin and myosin myofilaments. 3. Define a muscle system and compare and contrast skeletal, cardiac, and smooth muscle structure and function/contraction (drawing helpful! ) 2

The muscular system includes skeletal, cardiac, and smooth muscles, each with distinct structures and functions. Skeletal muscles are voluntary, striated, and attached to bones for body movement. Cardiac muscles are involuntary, striated, and found only in the heart for rhythmic pumping. Smooth muscles are involuntary, lack striations, and regulate internal organ functions like digestion through peristalsis. All three types involve contraction but differ in structure, control, and location. 4. Describe the electrical and chemical events leading up to skeletal muscle contraction 5. Distinguish between contraction, relaxation, agonists, antagonists, myofiber, myofibril and myofilament 6. Describe major factors that influence the strength and duration of muscle contraction (examples are energy source, sarcomere length, calcium cycling, muscle fiber type, frequency of stimulation, sarcomere length 7. Compare and contrast a single twitch, summation, tetanus, and muscle tone 8. Describe and define a motor unit 9. Give examples of contractile cells and tissues in invertebrates 3

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