Muscle Anatomy and Function

Flashcards covering key vocabulary and concepts related to muscle anatomy and physiology.

Muscle Tissue

Comprises three types: skeletal, cardiac, and smooth.

Skeletal Muscle

Voluntary, striated muscle fibers that make up skeletal muscle tissue.

Cardiac Muscle

Involuntary muscle found only in the heart, characterized by striations.

Smooth Muscle

Involuntary muscle found in internal organs; lacks striations.

Excitability

The ability of muscle tissue to respond to stimuli.

Contractility

The ability of muscle tissue to shorten forcibly when stimulated.

Extensibility

The ability of muscle tissue to be stretched.

Elasticity

The ability of muscle tissue to recoil to its resting length.

Epimysium

Connective tissue that surrounds the entire muscle.

Perimysium

Connective tissue that surrounds fascicles (groups of muscle fibers).

Endomysium

Connective tissue that surrounds each individual muscle fiber.

Myofibrils

Rodlike structures in muscle that have striations formed from repeating series of dark and light bands.

Sarcomere

The smallest contractile unit of muscle fiber, consisting of A bands and I bands.

Actin Myofilaments

Thin filaments anchored to Z discs, involved in muscle contraction.

Myosin Myofilaments

Thick filaments that form cross bridges with actin during contraction.

Cross Bridge Formation

The attachment of myosin heads to actin filaments during muscle contraction.

Neuromuscular Junction

The site where motor neurons meet muscle fibers.

Acetylcholine

Neurotransmitter released by neurons that stimulates muscle contractions.

Isometric Contraction

Muscle tension increases but does not change length; no shortening occurs.

Isotonic Contraction

Muscle changes in length and moves a load.

Muscle Tone

The resting slightly contracted state of all muscles.

Sarcoplasmic Reticulum

Network that regulates calcium concentrations in muscle cells.

Motor Unit

Consists of a motor neuron and all muscle fibers it supplies.

Hypertrophy

Increase in muscle size due to exercise.

Sarcopenia

The loss of muscle mass that begins around age 30.

Varicosities

Bulbous swellings of nerve fibers in smooth muscle that release neurotransmitters.

Myoblasts

Embryonic cells that develop into muscle tissue.

Caveolae

Infoldings of the sarcolemma in smooth muscle, containing calcium channels.

Gap Junctions

Connections between smooth muscle fibers that allow communication.

Troponin

A protein that binds calcium and moves tropomyosin to expose actin's binding site.

T-Tubules

Extensions of the sarcolemma that transmit electrical signals deep into muscle fibers.