Skeletal Muscle Anatomy and Physiology

Flashcards covering key terms and definitions related to skeletal muscle anatomy and physiology.

Sarcolemma

The plasma membrane that surrounds a muscle fiber.

Myofibril

The basic rod-like unit of a muscle cell, containing thick and thin filaments.

Sarcoplasm

The cytoplasm within a muscle fiber.

Neuromuscular Junction (NMJ)

The synapse or junction of the axon terminal of a motor neuron and the muscle fiber.

Motor Unit

A group of muscle fibers innervated by a single motor neuron.

T-tubules

Transverse tubules that allow electrical signals to penetrate deep into the muscle fiber.

Calcium Channels

Voltage-gated channels that open to allow calcium ions to flow in during muscle activation.

Troponin

A regulatory protein that binds calcium and controls muscle contraction by moving tropomyosin.

Myosin

A thick filament protein that interacts with actin to facilitate muscle contraction.

Actin

A thin filament protein that forms the basis of muscle contractions.

Z Discs

Structures that delineate the ends of a sarcomere, providing attachment sites for thin filaments.

A band

The dark region of the sarcomere where thick filaments are located.

I band

The light region of the sarcomere that contains only thin filaments.

H zone

The region in the sarcomere that contains only thick filaments.

Dystrophin

A protein that connects the muscle fiber to the sarcolemma; defects can lead to muscular dystrophy.

Creatine phosphate

A molecule that donates a phosphate group to ADP to quickly regenerate ATP for muscle contraction.

Myoglobin

A protein that carries and stores oxygen in muscle cells, facilitating ATP production.

Acetylcholine (ACh)

A neurotransmitter released at the neuromuscular junction that stimulates muscle contraction.

Sarcoplasmic Reticulum

A specialized type of smooth endoplasmic reticulum in muscle fibers, storing calcium ions.

Calquestrin

A calcium-binding protein found in the sarcoplasmic reticulum, sequestering calcium ions.