Bio124 Ch 10 + Muscles Part 1 SCHROETER PPT Fall 2024 PDF

Introduction to Muscles Ch 10  How to increase your success… Make & use study guide from powerpoints & follow along as you listen to lectures. Prepare (at least some of) the study guide after each lecture! Get a “study buddy”. Communicate with me for strategies Make an...

Introduction to Muscles Ch 10  How to increase your success… Make & use study guide from powerpoints & follow along as you listen to lectures. Prepare (at least some of) the study guide after each lecture! Get a “study buddy”. Communicate with me for strategies Make anatomy a high priority… Reward yourself & take exercise breaks in between your study periods. “Anatomy waits for no one!”...  -Muscular System- What does “muscle” mean? “Little Mouse” Why?... 3  Formation of Skeletal Muscle: Myoblasts: Embryonic cells that fuse to form single muscle fibers. Satellite cells: Myoblasts that do not fuse in the embryo but remain associated with muscle. In adult they can be stimulated to differentiate & fuse to damaged muscle fiber to repair or regenerate damaged muscle.  Muscular System ½ of our body weight! Pectoralis – “Of the breast” Vastus – Means “huge” Sartorius – “A tailor” Teres – “Round” 5  General Muscle Functions Body posture / Movement Movement of fluids / food / waste Constriction / dilation of tubes Heat generators Homeostasis 6 Three Types of Muscle Tissue 1. Skeletal- Responsible for movement of skeleton & organs. – Long, striated cells w/ multiple peripheral nuclei. – Referred to as voluntary muscle 2. Cardiac- Provides continuous, rhythmic contraction of heart. – Small, striated cells w/ branches & intercalated discs. – Structurally an intermediate of skeletal & smooth muscle. 3. Smooth- Forms muscular component of structures such as blood vessels & GI tract, uterus and urinary bladder. – Small, tapered, nonstriated cells – Referred to as involuntary muscle (i.e. under inherent autonomic & hormonal control) (Pages 306-309) Various functions- one activity! Muscles can only CONTRACT. Shorten in length. Muscles can pull! Muscles cannot push!!!… 8  To understand look at body movement Prime movers (Agonists) – action Antagonists – opposite of prime movers Synergists – Assists the prime movers… 9  Example - Flex the forearm… Prime mover? biceps brachii Antagonist? triceps brachii Synergist? Brachialis & brachioradialis… 10 So how do we “push” if muscles only pull! Levers! Olecranon process! Look at the bones! Read more about levers in text pages 303-4 11 How can we make this action more powerful? Make one end of the lever longer! 12 13 What mammal has the most favorable elbow lever? Broad-handed mole! 14 Horse scapula 15  Skeletal Muscle - Attachments (p. 287): What attaches muscle to bone? Tendon What tissue? – Dense regular connective tissue. 16  Skeletal Muscle Attachments (p. 291): Aponeurosis: Tendons that form thin, tough, flattened sheets… 17  Skeletal Muscle Attachment Origin: attachment that is more proximal or more stationary. Insertion: attachment that is more distal or more mobile. Belly = Body, main region that shortens & thickens when it contracts Creates the Action!... 18 Biceps brachii Action = Flexes forearm https://www.yoganatomy. com/ O-I-A Sternocleidomastoid? Action = Flexes neck and rotation of head https://www.yoganatomy.com/  O-I-A Biceps femoris? Origin? Ischium & proximal part of femur Insertion? Lateral condyle tibia & head of fibula Action? Flexes lower leg… 22  Muscle Shapes (p. 301-302): by fiber organization Parallel: fascicles run side-by-side (biceps brachii). Pennate: fibers come off sides of the tendon Types of pennate: 1. Unipennate: fibers come off one side (extensor digitorum). 2. Bipennate: more common, fibers come off both sides of the tendon (rectus femoris)… 23 Muscle Shapes (p. 301-302, continued) 3. Multipennate: many pennate muscles, together (deltoid). Convergent: fibers over a wide area but come together into a common tendon (pectoralis major). Circular = sphincter fibers are concentric around a body opening (orbicularis oris)… 24 Microscopic Anatomy (pp. 285-293): 25 Gross Anatomy of Skeletal Muscle Epimysium: surrounds the entire muscle Perimysium: surrounds each bundle (fascicle). Endomysium: surrounds muscle fiber. Satellite cells are scattered here & there. Satellite cells help repair tissue damage… Gross Anatomy of Skeletal Muscle  Introduction to Muscles: Level Muscle Level 1: Muscle Includes multiple Fascicles, housing many muscle fibers, connective tissue coverings, blood vessels, and nerve fibers. Covered by *connective tissue (collagen & elastic fibers) called Epimysium Epimysium: Made of dense irregular connective tissue that surrounds whole skeletal muscle.  Introduction to Muscles: Level Muscle Level 2: Fascicle Bundle of muscle fibers. Covered by *connective tissue covering called Perimysium. Perimysium: Made of dense irregular connective tissue with extensive association with blood supply.  Introduction to Muscles: Level - Muscle Fiber Sarcolemma Level 3: Muscle Fiber (Muscle Cell) Elongated, multinucleated, cylindrical fiber (cell); exhibits striations, contains myofibrils. Covered by *connective tissue covering called Endomysium. Endomysium: Made of Areolar & reticular tissue & electrically insulates each muscle fibers. Sarcolemma is the plasma membrane of the skeletal muscle cell….  Introduction to Muscles: Level Myofibril Sarcomere is contractile unit… Level 4: Myofibril Long, cylindrical contractile element within muscle fiber; as long as the muscle itself; composed of myofilaments; exhibits striations. Has no connective tissue covering.  Introduction to Muscles: Level Myofibril Transverse tubules (T-tubules) are structures that spread the nerve impulse throughout muscle causing muscle to contract. Sarcoplasmic reticulum are structures that store calcium and are necessary to initiate muscle contraction. Terminal cisternae are pairs of sacs of Sarcoplasmic reticulum that are adjacent to the T-tubule. Triad is the name given to the T-tubule and pair of Terminal cisternae. Introduction to Muscles: Level Myofibril Other Connective Tissue Components Superficial Fascia (A.K.A. subcutaneous layer) Areolar & Adipose tissue. Separates muscle from skin. Deep Fascia dense irregular tissue. Separates individual muscles, binds muscles with similar functions, and helps distribute blood vessels, nerves, and lymphatic vessel.  Muscle cell anatomy is different from other cells. 35 “Normal” Cell Membrane 36 In muscle, the plasma membrane is called the sarcolemma The deep tubular extensions of the sarcolemma are called T-tubules (Tubes) 37  The ER inside each muscle cell = SR = Sarcoplasmic Reticulum They end in sacs called terminal cisternae. 38 Terminal cisternae lay next to each T-tubule 39 Terminal cisternae are filled with Ca++ 40 Each set of three is called a triad – consisting of two terminal cisternae and one T-tubule. 41 T-tubules, carry nerve impulses from the surface sarcolemma deep into the sarcoplasm. Terminal cisternae – Sarcoplasmic reticulum: stores Ca++ until released when a nerve impulse arrives… 42 What triggers the action potential along the sarcolemma? ⚫ When the neuron action potential reaches the muscle fiber. ⚫ But first, it has to jump a gap. 43 When a nerve impulse reaches the synaptic nob (motor end plate), it releases acetylcholine from synaptic vesicles which crosses the synaptic gap (cleft) & binds to receptors on the sarcolemma. 44  That triggers the action potential (nerve impulse) across the entire sarcolemma and down the T-tubules. When the signal reaches the terminal cisternae, it releases the stored Ca++ 45 ***Summary Events of Muscle Conduction – page 296: Nerve impulse (A.P.) moves along a motor neuron Reaches synaptic knob (bulb) at the neuromuscular junction ACH is released and crosses the synaptic gap (cleft) This triggers an action potential on sarcolemma A.P. travels down T-tubules Ca++ is released from terminal cisternae Ca++ release ends conduction stage and begins muscle contraction… 46