Muscle Physiology and Action Potentials

These flashcards cover key vocabulary and concepts from muscle physiology and action potentials discussed in the lecture.

H band

The area of just myosin without overlap with actin.

Zone of overlap

The area where both actin and myosin overlap during muscle contraction.

H band

The area of just myosin without overlap with actin.

Zone of overlap

The area where both actin and myosin overlap during muscle contraction.

Sarcomere

The basic unit of a muscle fiber, consisting of a segment between two Z lines.

Myosin

A type of thick filament that interacts with actin to cause muscle contraction.

Actin

A type of thin filament that forms part of the muscle fiber and has binding sites for myosin.

Neuromuscular junction

The point where a motor neuron meets a muscle fiber, facilitating muscle contraction.

Acetylcholine

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

Action potential

An electrical signal that propagates down a neuron or muscle fiber, leading to contraction.

Sodium channels

Membrane proteins that allow sodium ions to enter a cell, contributing to depolarization.

Threshold voltage

The critical level to which a membrane potential must be depolarized to initiate an action potential.

Depolarization

The process by which a cell becomes more positive in charge due to sodium influx.

Repolarization

The process by which a cell returns to a more negative charge due to potassium efflux.

Hyperpolarization

An overshooting of the resting potential where the inside of the cell becomes more negative than resting potential.

Troponin

A protein that, when bound to calcium, causes tropomyosin to move and expose binding sites on actin.

Tropomyosin

A protein that blocks the binding sites on actin in a relaxed muscle fiber.

Calcium ions

Ions released from the terminal cisternae that bind to troponin and trigger muscle contraction.

ATP

A molecule that provides energy for muscle contraction and detachment of myosin heads.

All or nothing principle

The concept that a muscle fiber either contracts fully or not at all once the threshold is reached.

Rigor mortis

The stiffening of muscles after death due to lack of ATP preventing muscle relaxation.

Calcium channels

Ion channels that open to allow calcium ions to enter the axon terminal, triggering the release of neurotransmitters.

Acetylcholinesterase

An enzyme that breaks down acetylcholine in the synaptic cleft to terminate the signal for muscle contraction.