Muscle Tissue

Myology The scientific study of muscles

Orthopedics Branch of medicine concerned with the prevention or correction of disorders of the musculoskeletal system

Characteristics of Muscle Tissue Excitability – the ability to respond to a stimulus Contractility – the ability to shorten when stimulated Extensibility – the ability to be stretched Elasticity – the ability to return to the original size

Functions of Muscle Tissue Motion – body movements as well as moving substances within the body Posture – postural muscles continuously contract when awake to hold the body upright Heat Production – muscular contraction produces 85% of the body’s heat

Skeletal Muscle Location – attached to bones Appearance – striated Nervous Control - Voluntary

Cardiac Muscle Location – The Heart Appearance – striated Nervous Control - involuntary

Smooth Muscle Location – walls of hollow organs Appearance – non-striated Nervous Control - involuntary

Connective Tissue Fascia – sheets or bundles of fibrous connective tissue Superficial Fascia – just beneath the skin Deep Fascia – Holds muscles together  Epimysium – covers the entire muscle  Perimysium – covers a bundle of muscle fibers  Endomysium – covers individual muscle fibers

More connective tissue Tendon – cord-like extension of deep fascia that connects muscle to bone Aponeurosis – a sheet of connective tissue, similar to a tendon that attaches muscles

Nerve and Blood Supply Highly vascular and highly innervated Need to respond to stimuli (nerves) Uses lots of energy (ATP) so needs blood

Histology of Muscle Tissue Myofibers – muscle fiber (cell) Sarcolemma – plasma membrane Sarcoplasm – cytoplasm Sarcoplasmic Reticulum – ER Transverse Tubules (T-Tubules) – tubes that extend across the myofiber and open to the outside.

Myofibril – structures that make up the fibers Myofilaments – structures that make up the fibrils Sarcomeres – basic functional unit of skeletal muscles

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SARCOMERES Z-line – end of a sarcomere A-band – dark area made of think and thin filaments I-band – light area made of only thin filaments H-zone – light area made of only thick filaments

hill.com/sites/ /student_vie w0/chapter10/animation__sarcomere_c ontraction.html

Proteins Actin – protein that makes the thin filaments Myosin – protein that makes the thick filaments

Myology Resources hill.com/sites/ /student_view0/chapter10/