Neuromuscular Junction and Muscle Fiber Vocabulary

A set of vocabulary flashcards defining key structures and chemical messengers involved in muscle cell function and the neuromuscular junction.

Muscle fiber

Another name for a muscle cell.

Sarcolemma

The cell membrane of a muscle fiber.

Myofibril

A structure inside the muscle fiber that contains the proteins involved in muscle contraction.

Sarcoplasmic reticulum (SR)

A structure inside the muscle fiber that regulates the levels of calcium ions ($Ca^{2+}$) and releases $Ca^{2+}$ when stimulated by an electrical impulse.

T-tubules

Parts of the sarcolemma that extend deep into the muscle fiber, allowing an electrical impulse to travel deep into the muscle fiber.

Receptors

Binding sites on the muscle fiber that receive neurotransmitters.

Motor neuron

A neuron that carries messages to skeletal muscles and stimulates them to contract.

Action potential

An electrical impulse that travels along a neuron and, ultimately, through the muscle fiber.

Axon terminal

The end of the axon of a neuron.

Synaptic cleft

The tiny space between the axon terminal and the muscle fiber.

Neurotransmitter

A chemical messenger released by a neuron.

Acetylcholine (ACh)

The neurotransmitter used by motor neurons to communicate with skeletal muscle.

Neuromuscular junction (NMJ)

The place where a motor neuron and skeletal muscle fiber communicate.