MACRO AND MICROSTRUCTURE OF MUSCLE
Module 1: Anatomy and Physiology
Big Picture Things to Remember
Each skeletal muscle is an organ that contains muscletissue, connective tissue, nerves, and blood vessels.
Connective tissue names have the suffix -mysium.
Connective tissue is always on the outside of a bundleor cell.
The whole muscle is a bundle of bundles of musclecells.
Muscle cells contain bundles of the contractileproteins along with all of the other structures you'dexpect 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
Perimysium- surrounds the fasciculus (group of muscle fibers)
Endomysium-surrounds individual muscle cell
Muscle Cell Structure
Myofibrils
Muscle cells are made up of many (hundreds)myofibrils
Myofibrils contain myofilaments (contractileproteins)
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 atregular intervals
Anchored at the M Bridge (at the center of the H zone)
Sarcomere
The functional (or contractile) unit of a muscle
Motor Unit
Motor Unit is the motor nerve (neuron) and all themuscle fibers that it innervates
