Module 6: Muscle physiology

Electrochemical gradient

A difference in ion concentration across a membrane that creates a voltage difference.

Depolarization

The process by which the membrane potential becomes less negative, often leading to action potential.

Neuromuscular junction (NMJ)

The synapse between a motor neuron and muscle fiber, where neurotransmission occurs.

ACh (Acetylcholine)

A neurotransmitter that is released from axon terminals at the neuromuscular junction.

End plate potential

The change in membrane potential at the motor end plate resulting from ACh binding, bringing the potential to threshold.

T-tubules

Extensions of the sarcolemma that penetrate into the muscle cell, assisting in the transmission of action potentials.

Sarcoplasmic reticulum (SR)

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

Cross-bridge formation

The attachment of myosin heads to binding sites on actin, initiating contraction.

Power stroke

The action of myosin pulling actin filaments toward the sarcomere center during contraction.

Motor unit

A single motor neuron and all the muscle fibers it innervates, varying in size and function.