Muscle Contraction and Regulation Lecture

These flashcards cover key concepts related to muscle contraction mechanisms and the regulation of calcium ions within muscle cells.

Calcium Ions (Ca2+)

Essential ions required for muscle contraction, regulated and stored within muscle cells.

Troponin

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

Tropomyosin

A protein that wraps around actin and blocks binding sites; its position is altered by troponin when calcium is present.

Excitation Contraction Coupling

The process of converting an electrical signal from a nerve cell into a mechanical force in muscle.

Sarcoplasmic Reticulum

The storage facility for calcium ions within muscle cells, structured as a network of tubules.

Transverse Tubules (T Tubules)

Membrane passageways that conduct electrical signals deep within muscle fibers.

Mitochondria

Organelles that generate ATP for energy in muscle cells, involved in sustaining muscular activity.

Calcium ATPase

An ATP-powered pump that transports calcium ions back into the sarcoplasmic reticulum to promote muscle relaxation.

Motor Unit

A single motor neuron and all the muscle fibers it innervates, providing redundancy and control over muscle contraction.

Tension

The force exerted by a muscle during contraction.

Isometric Contraction

A type of contraction where the muscle generates force without changing length.

Isotonic Contraction

A contraction in which the muscle changes length while maintaining a constant tone.

Eccentric Contraction

A contraction in which the muscle lengthens while producing force, such as lowering oneself into a chair.

Load

The force or weight that a muscle must overcome when contracting.

Nicotinic Acetylcholine Receptors

Ionotropic receptors on the muscle cell membrane that respond to acetylcholine, causing depolarization.

DHP Receptor

Dihydropyridine receptor, a calcium channel that opens in response to depolarization in T tubules.

Ryanodine Receptor

Receptor that, upon activation by calcium from DHP receptors, releases additional calcium from the sarcoplasmic reticulum.