Question

DESCRIBE the internal anatomy of skeletal muscle, using each of the following terms: ACTIN, MYOSIN, THIN FILAMENT, THICK FILAMENT, MYOFIBRIL, MUSCLE FIBER, FASCICLE, ENDOMYSIUM, PERIMYSIUM, EPIMYSIUM, MUSCLE TISSUE

Answer 1

INTERNAL ANATOMY OF SKELETAL MUSCLE : SKELETAL MUSCLE IS OTHERWISE CALLED AS STRIATED OR VOLUNTARY MUSCLE. THEIR ACTIVITIES ARE UNDER THE VOLUNTARY CONTROL OF NERVOUS SYSTEM. THEREFORE, THEY ARE KNOWN AS VOLUNTARY MUSCLES. PRIMARY FUNCTION OF THIS MUSCLE IS LOCOMOTION AND CHANGES IN BODY POSTURE.

EACH MUSCLE IS MADE UP OF NUMBER OF MUSCLE BUNDLES OR FASCICLES. THESE FASCICLES ARE HELD TOGETHER BY A COMMON COLLAGENOUS CONNECTIVE TISSUE LAYER CALLED FASCIA.

EACH MUSCLE IS COMPOSED OF NUMEROUS MUSCLE FIBRES AND IT IS MULTINUCLEATED, CROSS STRIATED CYLINDRICAL CELLS. IT IS MADE UP OF SARCOLEMMA OR CELL MEMBRANE ENCLOSING SARCOPLASM (CYTOPLASM) . NUMBER OF EVENLY DISTRIBUTED LONGITUDINAL THREADS CALLED MYOFIBRILS ARE PRESENT IN THE SARCOPLASM.

MUSCLE-FASCICULE-FIBRE-MYOFIBRILS-MYOFILAMENTS

EACH MUSCLE IS AN INDIVIDUAL CELL AND CONSISTS OF FOLLOWING PARTS.

SARCOLEMMA,  SARCOPLASM, NUCLEI,  MYOFIBRILS, MYOFILAMENTS, MITOCHONDRIA, SARCOPLASMIC RETICULUM.

SARCOLEMMA IS CELL MEMBRANE OF MUSCLE FIBRES AND SARCOPLASM IS SEMIFLUID CYTOPLASM OF MUSCLE.

NUCLEI ARE MULTIPLE IN NUMBER AND OVAL IN SHAPE, PERIPHERAL IN DISTRIBUTION BENEATH THE SARCOLEMMA.

MYOFIBRILS ARE CONTRACTILE UNBRANCHED THREADS SITUATED ALONG THE MUSCLE FIBRE.  IT CONSIST OF ALTERNATE A-BAND

AND I-BAND. EACH MYOFIBRILS CONSISTS OF LONGITUDINALLY ARRANGED PROTEIN FILAMENTS SUCH AS THIN FILAMENT CONSISTS OF ACTIN, TROPOMYOSIN, TROPONIN WHEREAS THICK FILAMENT CONSISTS OF MYOSIN . THESE ARE CALLED MYOFILAMENTS.

MITOCHONDRIA PROVIDES ENERGY FOR THE WORK OF  MUSCLE FIBRE.

BESIDES THE ABOVE COMPONENTS THERE ARE THREE TYPES OF SUPPORTING TISSUES WHICH HELPS IN ORGANIZATION OF SKELETAL MUSCLES. THESE ARE.

ENDOMYSIUM : IT IS A DELICATE SHEATH OF CONNECTIVE TISSUE WHICH COVERS EACH MUSCLE FIBRE OUTSIDE THE SARCOLEMMA.

PERIMYSIUM : THE MUSCLE FIBRES ARE GROUPED INTO FASCICULI EACH FASCICULUS IS COVERED BY A CONNECTIVE TISSUE SHEATH CALLED PERIMYSIUM.

EPIMYSIUM : THE ENTIRE MUSCLE IS COVERED BY A SHEATH OF CONNECTIVE TISSUE KNOWN AS THE EPIMYSIUM.