Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Muscle Tissue II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated a. Skeletal b. Cardiac 2. Smooth B. Muscle Development (Skeletal) V. Summary SEM of partly unraveled skeletal muscle cell exposing the densely packed myofibrils within. Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction II. Learning Objectives III. Keywords Muscle Tissue IV. Slides A. Types of Muscle 1. Muscle is a highly cellular and vascular tissue 1. Striated specialized for contraction via the interaction of a. Skeletal myofilaments (between thin and thick filaments); b. Cardiac it is responsible for movement of the body and for 2. Smooth changes in the size and shape of internal organs. B. Muscle Development (Skeletal) V. Summary 2. There are three basic types of muscle tissue (skeletal, smooth, and cardiac) classified according to appearance of their contractile cells and location. 3. Striated muscle is formed during development by the fusion of small individual muscle cells called myoblasts into larger, multinucleated myotubes. Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Learning Objectives II. Learning Objectives III. Keywords 1. Understand the structural features of three general types of muscle cells IV. Slides and how each is organized to form a contractile tissue that performs A. Types of Muscle specific types of work. 1. Striated a. Skeletal 2. Understand the structural and functional attributes of connective tissues b. Cardiac associated with muscle and the myotendinous junction. 2. Smooth B. Muscle Development (Skeletal) 3. Understand that skeletal muscle contains different types of fibers V. Summary 4. Understand the arrangement of actin and myosin filaments in all three muscle types. 5. Understand the arrangement and roles of transverse tubules, sarcoplasmic reticulum, mitochondria, and contractile filaments in the process of contraction 6. Understand the locations and roles of intercellular junctions in muscle 7. Understand the response of muscle to injury and the regenerative capacity of the various types of muscle. Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction II. Learning Objectives Keywords III. Keywords IV. Slides A. Types of Muscle A-band Myofibrils 1. Striated Cardiac muscle Myotube a. Skeletal Endomysium Perimysium b. Cardiac Epimysium Sarcoplasmic reticulum 2. Smooth Fascicles Satellite cell B. Muscle Development (Skeletal) I-band Skeletal muscle V. Summary Intercalated disc Smooth muscle Muscle fiber Striated muscle Myoblast Striations Myocardium T tubule Myocytes Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 7: Larynx, Trichrome II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated a. Skeletal look here to see b. Cardiac skeletal muscle in 2. Smooth longitudinal-section B. Muscle Development (Skeletal) V. Summary look here to see skeletal muscle in cross-section Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 7: Larynx, Trichrome II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle endomysium 1. Striated a. Skeletal b. Cardiac 2. Smooth perimysium B. Muscle Development (Skeletal) V. Summary individual skeletal muscle fibers (i.e., cells) seen in cross-section epimysium fascicle in skeletal muscle, endomysium is a delicate layer of reticular CT surrounding individual muscle fibers (cells); perimysium is thicker connective tissue surrounding a group of fibers to form a bundle or fascicle; epimysium is a sheath of dense connective tissue surrounding a collection of fascicles that constitute an entire muscle the endo-, peri-, epi- prefixes for surrounding layers of connective tissue will be seen again for other structures, such as the layers of CT surrounding peripheral nerves, so it is important to be familiar with their meaning and usage Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 70: Tongue, H&E II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated a. Skeletal surface of tongue; b. Cardiac what specific type of tissue is this? 2. Smooth B. Muscle Development (Skeletal) V. Summary skeletal muscle skeletal muscle (or visceral striated muscle, as seen in the tongue) is generally responsible for voluntary movement within the body, mainly of the skeleton but also other structures such as the eyes and upper esophagus for swallowing; it is composed of long multinucleated cells called muscle fibers which generally extend the entire length of a muscle from tendon to tendon (up to 2ft long in the sartorius muscle in the thigh) Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 70: Tongue, H&E II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated a. Skeletal skeletal muscle b. Cardiac in longitudinal-section 2. Smooth B. Muscle Development (Skeletal) V. Summary skeletal muscle in cross-section Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 70: Tongue, H&E II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated notice that the nuclei of the a. Skeletal skeletal muscle fibers b. Cardiac have been displaced to the 2. Smooth periphery of the fiber/cell B. Muscle Development (Skeletal) by all the myofibrils filling V. Summary the cell endomysium surrounds individual muscle fibers perimysium surrounds the entire muscle fascicle (composed of multiple muscle fibers/cells) Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 8: Tongue, Trichrome II. Learning Objectives III. Keywords skeletal muscle IV. Slides in longitudinal-section A. Types of Muscle 1. Striated skeletal muscle fiber a. Skeletal in cross-section b. Cardiac 2. Smooth fibroblast of the B. Muscle Development (Skeletal) endomysium CT V. Summary nucleus of a muscle fiber displaced to the periphery, directly under the sarcolemma skeletal muscle in longitudinal-section numerous capillaries can be seen in the endomysium between the muscle fibers using the know size of an RBC, estimate the diameter of an adjacent muscle fiber Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 17 (464): Skeletal Muscle, H&E II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle a few nuclei of fibroblasts, 1. Striated forming the endomysium a. Skeletal or perimysium, may be b. Cardiac seen but can be difficult to 2. Smooth identify; the nuclei of B. Muscle Development (Skeletal) endothelial cells of V. Summary capillaries can also be seen nuclei of skeletal muscle fibers are displaced to the periphery of the cells directly beneath the sarcolemma cross-striations (fine lines) are the alternating dark and light bands formed by the arrangement of the myofilaments of the sarcomere (best seen in electron micrographs); the dark bands are the A-bands (overlapping actin and myosin filaments) and the light bands are the I-bands (actin filaments); the visible striations are the reason both skeletal and cardiac muscle are classified as striated muscle Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 139: Heart, H&E II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated a. Skeletal b. Cardiac 2. Smooth B. Muscle Development (Skeletal) V. Summary cardiac muscle is striated muscle, like skeletal muscle; however, it is localized to the walls of the heart and is distinguishable by: (1) the branching of its muscle fibers; (2) a single nucleus per cell, generally round and found near the center of the cell; and (3) the presence of intercalated discs between cells, so that the fibers are actually many cells linked end-to-end, unlike the fibers of skeletal muscle which are a single multinucleated cell Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 139: Heart, H&E II. Learning Objectives III. Keywords IV. Slides round, centralized A. Types of Muscle nucleus of cardiac muscle is distinct from 1. Striated the multinucleated a. Skeletal peripheral, elongated b. Cardiac what is this nuclei of skeletal muscle 2. Smooth “wear and tear” B. Muscle Development (Skeletal) pigment found V. Summary near the nuclei cross-striations in cardiac fibers? (thin, faint lines) intercalated disc (thick, dark lines) “branching” of fibers myofibrils is characteristic of (parallel to fiber direction) cardiac muscle intercalated discs are highly specialized cell-to-cell adhesion junctions found in cardiac muscle; they physically bind cells together to create long muscle fibers, so the force of contraction is transmitted between the cells; they also promote the spread of action potentials from cell to cell via gap junctions Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 66: Esophagus, H&E II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated a. Skeletal b. Cardiac lumen 2. Smooth B. Muscle Development (Skeletal) V. Summary look in the outer layer to see smooth muscle in cross-section look in the inner layer to see smooth muscle in longitudinal-section Lab 9 – Muscle Tissue IUSM – 2016 I. Introduction Slide 66: Esophagus, H&E II. Learning Objectives III. Keywords IV. Slides A. Types of Muscle 1. Striated a. Skeletal b. Cardiac 2. Smooth elongated, centrally- located nucleus of B. Muscle Development (Skeletal) smooth muscle fiber V. Summary seen longitudinally smooth muscle fibers are long and tapered at both ends, generally ranging in length from 20-200µm; there are no striations (hence, “smooth”) because the actin and myosin filaments do not show the same degree and kind of organization as seen in striated muscle (skeletal and cardiac); like in cardiac muscle, there is a single, central nucleus for each cell; however,