Muscle Anatomy and Physiology – Core Vocabulary

Vocabulary flashcards covering key terms from the lecture on muscle tissue types, structure, and physiology.

Skeletal muscle

Striated, voluntary muscle attached to bones (or facial skin) responsible for body movement

Smooth muscle

Non-striated, involuntary muscle forming the walls of hollow organs and blood vessels

Cardiac muscle

Striated, involuntary muscle found only in the heart, connected by intercalated discs

Fascicle

A bundle of skeletal muscle fibers surrounded by the connective tissue sheath called the perimysium

Perimysium

Connective tissue layer that wraps around each fascicle within a skeletal muscle

Endomysium

Delicate connective tissue that encloses each individual muscle cell (fiber)

Myofibril

Cylindrical organelle within a muscle cell composed of repeating units of actin and myosin filaments

Sarcomere

The smallest functional contractile unit of striated muscle, formed by repeating arrangements of myofilaments

Actin

Protein that forms thin filaments in myofibrils and interacts with myosin during contraction

Myosin

Motor protein forming thick filaments that pull on actin to shorten sarcomeres

Thick myofilament

Filament primarily made of myosin within the myofibril

Thin myofilament

Filament primarily made of actin within the myofibril

Sliding Filament Theory

Model stating that muscle contraction occurs as actin and myosin filaments slide past each other, shortening the sarcomere

Neuromuscular junction (NMJ)

Synapse where a motor neuron communicates with a muscle fiber to initiate contraction

Action potential

Rapid, transient change in membrane voltage that propagates along a cell membrane, triggering events such as muscle contraction

Intercalated disc

Specialized junction between cardiac muscle cells that facilitates electrical coupling

Voluntary muscle

Muscle whose contraction is consciously controlled by the nervous system (e.g., skeletal muscle)

Involuntary muscle

Muscle that contracts without conscious control, regulated by the autonomic nervous system or pacemakers (e.g., smooth and cardiac muscle)