Biology-232 GENERAL HISTOLOGY 4. Muscular Tissue Dr. Manal Othman Anatomy Department CMMS, AGU
Responsible for MOST types of BODY MOVEMENT Made up of groups of elongated MUSCLE cells with contractile filaments 2
Terminologies Sarcolemma Sarcoplasm Sarcoplasmic reticulum Sarcomere 3
Classification : Morphology STRIATED Have characteristic alterations of dark and light bands, Non striated No striations Located in walls of blood vessels, viscera. 4
Classification : Function VOLUNTARY Conscious control INVOLUNTARY No conscious control 5
Classification : Morphology and Function SKELETAL MUSCLE CARDIAC MUSCLE SMOOTH MUSCLE 3 types, morphology / function Strong, quick discontinuous VOLUNTARY CONTRACTION Striated cylindrical non branching Strong, quick continuous INVOLUNTARY CONTRACTION Striated cylindrical branching Weak, slow INVOLUNTARY CONTRACTION non-striated Spindle shape 6
SKELETAL MUSCLE Long muscle fibers Cylindrical, multinucleated cells Oval nuclei found at periphery of cell, under the cell membrane Striations present Pink to red in color due to rich vascular supply and presence of myoglobin pigments 7
SKELETAL MUSCLE FIBERS (H&E picture)
SKELETAL MUSCLE FIBERS
Connective tissue coverings 1. Epimysium (dense irreg CT) 2. Perimysium (invagination Ms bundles) 3. Endomysium (delicate CT) 10
Organization of SKELETAL MUSCLE FIBER Sarcomere - Smallest subunit of contractile apparatus Z LINE or disk A BAND I BAND H BAND pale area, center of A band 11
SKELETAL MUSCLE FIBERS (Sarcomere)
Electron microscopic picture
MOTOR END PLATE Myoneural junction Branching myelinated motor nerves dilated termination 14
CARDIAC MUSCLE Cross-striated banding pattern 1 or 2 centrally-located palestaining nuclei Endomysial CT has a rich capillary network structure & function: diads (1 t-tubule & 1 sarcoplasmic reticulum cisterna) 15
CARDIAC MUSCLE FIBERS Striated, branched cells with intercalated disks (junctional complexes). Contain 1 2 central large pale nuclei. Rhythmic contraction.
CARDIAC MUSCLE FIBERS (H&E picture)
Electron microscopic picture Only 1 or 2 centrally- located pale staining nuclei Contains numerous mitochondriaoccupy 40% or more of the cytoplasmic volume 18
INTERCALATED DISK represent junctional complexes between adjacent cardiac muscle cells 3 main junctional specializations 1. Zonula adherens: (Fasciae adherentes) most prominent found in transverse portions, serves as anchoring sites for actin filaments of terminal sarcomeres 19
2. Maculae adherentes (desmosomes) found in transverse portions, bind cardiac cells together to prevent their pulling apart under constant contractile activity 3. Gap junction found in lateral portions, provide ionic continuity between adjacent cells
SMOOTH MUSCLE Elongated non-striated spindle shaped cells Length: 20 um (small bld vessels) & 500 um (pregnant uterus) Each cell oval nucleus located in center 21
SMOOTH MUSCLE FIBERS Elongated, nonstriated, fusiform cells with single central nucleus (folded and tapers). Located in walls of respiratory, GIT, urinary, and blood vessels
SMOOTH MUSCLE FIBERS (H&E picture)
ORGANELLES Mitochondria Sarcoplasmic reticulum branching network of cisternae Transverse tubules finger-like invaginations of sarcolemma, regulation of Ca+ Skeletal muscle TRIAD 2SR + 1TT (Present at AI junction) Cardiac muscle DIAD 1SR + 1TT (present at Z line) Smooth muscle NO T- tubules 24
Regeneration of MUSCLE TISSUE SKELETAL MUSCLE undergo limited regeneration, source or regenerating cells is believed to be the satellite cells SMOOTH MUSCLE capable of active regenerative response - Undergo mitosis CARDIAC MUSCLE virtually no regenerative capacity beyond early childhood - Defects or damage (eg. infarcts) are generally replace by proliferation of connective tissue (myocardial scars) 26