Muscle Physiology and Neuromuscular Junction

A collection of vocabulary flashcards covering key terms related to muscle physiology, the neuromuscular junction, and muscle contraction types.

Motor unit

A motor unit consists of a motor neuron and all the muscle fibers it innervates.

Neuromuscular junction

The synapse or junction between a motor neuron and a muscle fiber.

Synaptic cleft

The small space between the synaptic knob of a motor neuron and the muscle fiber.

Acetylcholine

A neurotransmitter released at the neuromuscular junction to trigger muscle contraction.

End plate potential

The local depolarization of the motor end plate when acetylcholine binds to its receptors.

Action potential

A rapid change in membrane potential that propagates along the sarcolemma and down the t-tubules, leading to muscle contraction.

Resting membrane potential

The difference in charge across the cell membrane of a resting muscle cell, typically around -90 mV.

Fast twitch fibers

Muscle fibers characterized by quick, powerful contractions but fatigable.

Slow twitch fibers

Muscle fibers that provide sustained, endurance-type contractions relying primarily on aerobic metabolism.

Tetany

A condition of continuous muscle contraction that occurs when nerve signals stimulate muscles at a high frequency.

Isometric contraction

A type of muscle contraction where tension is increased without a change in muscle length.

Isotonic contraction

A type of muscle contraction where muscle changes length while contracting, which can be concentric or eccentric.

Calmodulin

A calcium-binding messenger protein that plays a role in smooth muscle contraction.

Gap junctions

Intercellular junctions allowing ions and small molecules to pass between cardiac muscle cells, facilitating coordinated contractions.

Troponin

A regulatory protein that binds calcium ions and allows muscle contraction by enabling myosin to bind to actin.

Myofibrils

Long, slender organelles found in muscle cells that contain the contractile proteins actin and myosin.

Muscle tone

The slight tension in muscles at rest, maintained by involuntary nerve impulses.

Sarcoplasmic reticulum

An organelle in muscle cells that stores calcium ions and releases them during muscle contraction.