Muscles and Muscle Tissue

These flashcards cover key concepts, terms, and definitions relevant to muscle tissue and contraction.

Myo, mys, and sarco

Prefixes related to muscle; e.g., sarcoplasm refers to the cytoplasm of a muscle cell.

Skeletal muscle

Muscle that attaches to bones and skin, is striated, voluntary, and can contract rapidly.

Cardiac muscle

Muscle found only in the heart, striated, involuntary, and contracts at a steady rate due to the heart's pacemaker.

Smooth muscle

Muscle found in walls of hollow organs, non-striated, and involuntary.

Excitability

The ability of muscle tissue to receive and 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 resting length.

Acetylcholine (ACh)

A neurotransmitter that transmits signals from motor neurons to muscle fibers.

Neuromuscular Junction

The synapse between a motor neuron and a skeletal muscle fiber.

Triad

Structure formed by the terminal cistern of the sarcoplasmic reticulum, T tubule, and the terminal cistern of another sarcomere.

Myofibrils

Rodlike elements densely packed in muscle fibers, accounting for ~80% of muscle cell volume.

Cross bridge cycling

The mechanism by which muscle contraction occurs through the binding and detachment of myosin heads to actin.

Tropomyosin

A regulatory protein that blocks myosin-binding sites on actin in low calcium conditions.

Troponin

A regulatory protein that binds to calcium and facilitates muscle contraction by moving tropomyosin.

Duchenne muscular dystrophy (DMD)

An inherited muscular dystrophy characterized by progressive muscle degeneration.

Sarcoplasmic reticulum

A network of smooth endoplasmic reticulum tubules surrounding myofibrils, regulating calcium levels.

Sliding filament model

Mechanism explaining how muscle fibers contract by the sliding motion of actin and myosin filaments over one another.