Muscle Fiber Contraction and Types

This set of flashcards covers key vocabulary and important concepts related to muscle fiber contraction and types.

Acetylcholine (ACh)

A neurotransmitter that triggers muscle contraction at the neuromuscular junction.

Sarcoplasmic Reticulum (SR)

A specialized endoplasmic reticulum in muscle cells that stores calcium ions (Ca2+).

Tropomyosin

A protein that covers the active sites on actin filaments at rest, preventing myosin from binding.

Troponin

A protein complex that, when bound to Ca2+, moves tropomyosin and exposes active sites on actin.

Sliding Filament Theory

The theory explaining muscle contraction where myosin heads pull actin filaments toward the center of the sarcomere.

Type I Muscle Fibers

Slow-twitch fibers that are fatigue-resistant and primarily use aerobic metabolism.

Type II Muscle Fibers

Fast-twitch fibers that generate more force but fatigue quickly, supporting anaerobic metabolism.

Motor Unit

A motor neuron and all the muscle fibers it innervates, which acts as a functional unit for muscle contraction.

Henneman Size Principle

The principle stating that motor units are recruited from smallest to largest based on the force required.

Concentric Contraction

Type of contraction where the muscle shortens while generating force.

Eccentric Contraction

Type of contraction where the muscle lengthens while generating force.

Isometric Contraction

Type of contraction where the muscle generates force without changing length.

Calcium Ions (Ca2+)

Ions that play a crucial role in muscle contraction by enabling actin-myosin interaction.

Titin

A protein that stabilizes myosin filaments and acts like a spring during muscle contraction.

Myosin

Thick filaments in muscle cells that interact with actin to produce contraction.