MACRO AND MICRO STRUCTURE OF MUSCLE Module 1

MACRO AND MICRO STRUCTURE OF MUSCLE Module 1: Anatomy and Physiology

Big Picture Things to Remember Each skeletal muscle is an organ that contains muscle tissue, connective tissue, nerves, and blood vessels. Connective tissue names have the suffix -mysium. Connective tissue is always on the outside of a bundle or cell. The whole muscle is a bundle of bundles of muscle cells. Muscle cells contain bundles of the contractile proteins along with all of the other structures you'd expect to find in a cell (nuclei, mitochondria, etc. ). The terms myo- and sarco- refer to muscle.

Muscle’s Connective Tissue Epimysium- covers the entire muscle Endomysium-surrounds individual muscle cell Perimysium- surrounds the fasciculus (group of muscle fibers)

Muscle Cell Structure

Myofibrils Muscle cells are made up of many (hundreds) myofibrils Myofibrils contain myofilaments (contractile proteins) Two myofilaments are: Actin Myosin

Actin Thin filaments Contain troponin and tropomyosin Anchored to the Z lines

Myosin Thick filaments Have globular heads, called cross-bridges, that stick out at regular intervals Anchored at the M Bridge (at the center of the H zone)

Sarcomere The functional (or contractile) unit of a muscle

Motor Unit is the motor nerve (neuron) and all the muscle fibers that it innervates