Muscle Lecture Slides PDF

Muscle Tissue Dr. Fernando A. Rodríguez-Rodríguez Ponce Health Sciences University School of Medicine Anatomical Sciences Division References: Ross/Pawlina (7th. Edition) & Cui  Muscle Tissue Consists of elongated cells called muscle fibers (muscle cells) Function...

Muscle Tissue Dr. Fernando A. Rodríguez-Rodríguez Ponce Health Sciences University School of Medicine Anatomical Sciences Division References: Ross/Pawlina (7th. Edition) & Cui  Muscle Tissue Consists of elongated cells called muscle fibers (muscle cells) Function: to move structures to produce contractions Terminology: – Fiber: muscle cell – Myo: muscle – Sarco: muscle  Muscle Tissue general classification 2 Striated muscle: – Skeletal muscle: Is attached by at least 1 end to some part of the skeleton Bundles of long (up to 100µm in diameter), cylindric, multinucleated cells (peripheral nuclei) with croos-striations Strong contractions for short duration Contraction is typically under voluntary control (somatic innervation)  Muscle Tissue general classification 2 Striated muscle (cont.): – Cardiac muscle: Constitutes most of substances of heart (some walls of pulmonary veins and superior vena cava) Has both croos-striations and intercalated discs (site of contact between individual cardiac muscle cells) Cells smaller than skeletal (10-20µm in diameter), are branched with 1 or 2 nuclei located centrally Rhythmic, strong, unfaltering contractions under involuntary control (autonomic innervation)  Muscle Tissue general classification Non-striated muscle: – Smooth muscle: Collection of fusiform cells with NO striations Arranged in sheets and constitute layers in walls of tubes and certain hollow structures: – Chief role: regulated size of their lumina or cavities by its degree of contraction Weaker contractions for long duration Contraction process is involuntary (autonomic innervation)  Skeletal Muscle Organization of CT components: – Epimysium = Around a whole muscle: Dense CT continuous with the tendon – Perimysium = Around a fascicle (bundles) Contains larger blood vessels and nerves – Endomysium = Around cells: Contains capillaries and nerve endings Is like a basal lamina – Function: To transfer the pull of the muscle cells to the bone (CAM’s) Skeletal muscle (Diagram)  Skeletal Muscle (Masson’s trichrome) Skeletal Muscle  Organization of the muscle Muscle → Fascicles → Fibers → Myofibril → Myofilaments (actin & myosin) The muscle fibers is croos-banded: Sarcome, Z line, I band, A band, H band, M lines, desmin T- system: Transverse tubule (T tubules), triads, sarcoplasmic reticulum (SR) Control of contraction and coordinator: – Motor nerve: neuromuscular junction & motor end plate – Sensory nerve: neuromuscular spindle Organization of a skeletal muscle Sarcomers in different functional stages Striations of a skeletal muscle (LM) Striations of a skeletal muscle (EM) Striations of a skeletal muscle (EM) T-System (Triad) Neuromuscular Junction Neuromuscular Junction Neuromuscular Junction/Motor Unit Motor End Plate Spindle Muscle Cardiac Muscle (Diagram) Cardiac Muscle Cardiac Muscle Cardiac Muscle Cardiac Muscle Intercalated Disc Diagram –Cardiac Muscle Cardiac Muscle – Diads Smooth muscle (Diagram) Smooth Muscle  Smooth Muscle (Masson’s trichrome) Smooth Muscle Smooth Muscle Smooth Muscle Smooth Muscle (EM) Smooth Muscle (EM)