Principles of Human Physiology - Muscle Physiology

This set of flashcards covers key vocabulary terms and concepts related to muscle physiology, focusing on skeletal muscle structure, contraction mechanisms, and excitation-contraction coupling.

Skeletal Muscle Structure

Muscles connected to two or more bones by tendons, with exceptions like facial muscles connected to skin.

Myofiber

A muscle fiber that is multinucleated and extends the length of the muscle.

Sarcoplasmic Reticulum

The smooth endoplasmic reticulum in muscle fibers that stores Ca2+.

Crossbridge Cycle

The cyclical formation and breaking of links between actin and myosin that generates force during muscle contraction.

Excitation-contraction coupling

The process that connects the excitation of a muscle fiber to the development of contraction through Ca2+ release.

A band

The dark band in a sarcomere that contains myosin and represents the area of overlap with actin.

I band

The light band in a sarcomere that contains only actin and no overlapping thick filaments.

Troponin

A regulatory protein that binds to Ca2+ and helps control the contraction of skeletal muscle by shifting tropomyosin.

Tropomyosin

A regulatory protein that overlaps myosin binding sites on actin, preventing contraction when muscle is relaxed.

Titin

A structural protein that anchors thick filaments between the M line and the Z line, providing elasticity and structural support.

Myosin

The thick myofilament in muscle fibers responsible for crossbridge formation and force generation.

Actin

The thin filament in muscle fibers that myosin fibers bind to during contraction.

Neuromuscular Junction

The synapse where a motor neuron communicates with a myofiber, leading to muscle contraction.

End-plate Potential (EPP)

A graded potential that occurs in a muscle cell due to the binding of acetylcholine at the motor end plate.

Ca2+-ATPase

An enzyme in the sarcoplasmic reticulum that helps transport Ca2+ back into the lumen to relax the muscle.