Muscles and Muscle Contraction: Anatomy and Function, Slides of Biology

Download Muscles and Muscle Contraction: Anatomy and Function and more Slides Biology in PDF only on Docsity! Muscular System- Part 1 Unit 5 Miss Wheeler Fun Facts! › The tongue is the strongest muscle in your body › The smallest muscles in the body are in the middle ear › The largest muscle in the body is the gluteus maximus ›  It takes 17 muscles to smile, and 43 muscles to frown › The heart is the only muscle that never gets tired Muscle Tissue › Three muscle types (you already know these): 1.  Smooth Muscle 2.  Cardiac Muscle 3.  Skeletal Muscle Smooth Muscle › How blood and food move › No striations › Single nucleus ›  Involuntary › Spindle-shaped cells › Found in walls of hollow organs (intestines, blood vessels) Cardiac Muscle › Makes your heart beat › Striations › Single nucleus ›  Involuntary › Cells jointed to each other at intercalated discs › Found only in the heart Try This! A. Smooth B. Cardiac C. Skeletal ______________ involuntary ______________ striated ______________ moves bones ______________ voluntary ______________ this picture à Structures of Skeletal Muscle › Epimysium- covers the entire skeletal muscle › Perimysium- covers a bundle of fibers (fascicle) › Endomysium- covers a single muscle fiber (cell) Structures of Skeletal Muscle › Sarcolemma- muscle fiber membrane › Sarcoplasm- cytoplasm of muscle fiber › Sarcoplasmic Reticulum- transport (ER). Store calcium › Myofibrils- organelle structure that takes up most of the space in a muscle fiber › Myofilaments- thread- like proteins that make up a myofibril (b) (ce) Thin (actin) filament = ey Elastic (titin) filaments || = pummel anteriat esd > ie, ™* yes sanort ——{ |i Copyright © 2001 Benjamin Cummings, an imprint of Addison Wesley Longman, Inc. Try This! Muscle composed of Individual types composed of composed of bundles cells filaments dark light composed of fibrils Twizzler Analogy Many packages of Twizzlers together = fascicle Find a fascicle on your diagram Iwizaler Analogy Muscle Fiber Nucleus [; BF Myofibrils —~ (Su SS be Sa? Filaments containing | actin and myosin pete Try This! Now try making your own model of a skeletal muscle using only the materials you are given. ca skeletal muscle cells } S * biceps muscle (contracted) triceps muscle (relaxed) biceps muscle (relaxed) triceps muscle (contracted) How muscles contract to move the skeleton © 2006 Encyclopedia Britannica, Inc. Where Does It Start? Skeletal muscle contraction begins at the neuromuscular junction. What do you think the neuromuscular junction is? Neuron Axon terminal Cell body Axon Motor unit = motor neuron & muscle fiber that it activates More motor units = stronger contractions of the muscle Neuromuscular Junction Steps #1-3 f | Motor neuror } axon Sarcolemma  Sarcomere Contraction — tseps#4. Actin Myosin Myosin Troponin: filament filament heads as ® tropomyosin Actin Ca** complex / @ raf Myosin is prevented from bonding with actin by the ~ Sarcomere before contraction Actin movement : Actin movement — << —e > wl ) . ‘ Seer By: {ap Sarcomere after contraction . ' Sliding Filament Theory › Actin and myosin filaments “slide” past each other as a muscle contracts Resting Muscle 1.  ATP binds to myosin arm 2.  ATP breaks down into ADP + P, reading to be activated Step 1. Action Potential 1.  A nerve action potential releases acetylcholine 2.  Signal gets sent to sarcoplasmic reticulum, which releases calcium Step 2. Myosin-Actin Binding 1.  Calcium binds to troponin 2.  Causes tropomyosin to move out of the way of the actin binding site 3.  Actin and myosin bind using energy from ATP Types of Muscle Contractions ›  Isotonic Contractions- the myofilaments are successful in their sliding movements. The muscle shortens, and movement occurs ›  Ex. Bending the knee, smiling ›  Isometric Contractions- contractions in which the muscles do not shorten. Tension develops in the muscle and it attempts to slide the filaments ›  Ex. When you push against a wall or try to lift a very heavy object lsotonic Contractions Isometric Contractions (a) Muscle contracts \ and shortens