Muscle Tissue and Contraction

These flashcards cover essential vocabulary related to muscle tissue structure and function, aiding in understanding muscle contraction mechanisms.

Types of muscle tissue

There are three types of muscle tissue: skeletal, cardiac, and smooth.

Skeletal muscle

Voluntary muscle tissue attached to bones, responsible for movement.

Cardiac muscle

Involuntary muscle that makes up the heart, responsible for pumping blood.

Smooth muscle

Involuntary muscle found in walls of hollow organs, responsible for peristalsis and other functions.

Sarcolemma

The muscle cell membrane that surrounds each muscle fiber.

Sarcoplasm

The cytoplasm of a muscle cell, containing myofibrils, myoglobin, and glycogen.

Myofibrils

Long bundles of proteins within a muscle cell that play a key role in muscle contraction.

Myoglobin

A protein that stores oxygen for use by muscle cells.

Glycogen

A form of stored glucose that provides energy for muscle contraction.

Transverse tubules (T-tubules)

Tube-like structures that penetrate the sarcolemma and are filled with extracellular fluid.

Sarcoplasmic reticulum (SR)

The endoplasmic reticulum of muscle cells that stores calcium ions.

Terminal cisternae

Sacs of the sarcoplasmic reticulum that store calcium, closely associated with T-tubules.

Sarcomere

The functional unit of muscle fibers, organized from thick and thin filaments.

Thick filaments

Composed primarily of myosin proteins, responsible for muscle contraction.

Thin filaments

Composed primarily of actin, along with troponin and tropomyosin, involved in muscle contraction.

Tropomyosin

A protein that blocks the active site of myosin on actin in relaxed muscles.

Troponin

A protein that regulates the position of tropomyosin in response to calcium.

Sliding filament model

The process by which muscle contraction occurs through the sliding of thick and thin filaments past one another.

A band

The dark region of a sarcomere that contains thick filaments.

I band

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

Z disk

The boundary between adjacent sarcomeres.

M line

The midline of the sarcomere.

H zone

The region of the sarcomere that contains thick filaments only.