Muscle Tissue

These flashcards cover key concepts and definitions related to muscle tissue, including characteristics, types of muscles, contraction mechanisms, and muscle metabolism.

All muscle cells have the following characteristics: Excitability, Conductivity, Contractility, Extensibility, and ****__.

Elasticity—returns to its original rest length after being stretched.

Skeletal muscle is ****__, meaning it is usually subject to conscious control.

voluntary

The average diameter of a skeletal muscle fiber is **** micrometers and can be as long as **** cm.

100, 30

The connective tissue that surrounds each muscle fiber is called ****__.

Endomysium

The ****__ is the plasma membrane of a muscle fiber.

Sarcolemma

****__ are stem cells that fuse to form each muscle fiber early in development.

Myoblasts

The thick filaments in muscle fibers are made of ****__ molecules.

myosin

In muscle contraction, calcium binds to ****__ which then moves tropomyosin off the active sites on actin.

troponin

The functional contractile unit of muscle fiber is called a ****__.

sarcomere

At the neuromuscular junction, the axon terminal releases the neurotransmitter ****__.

acetylcholine (ACh)

The ****__ is the point where a motor neuron meets a muscle fiber.

neuromuscular junction (NMJ)

Rigor mortis occurs when muscle fibers stiffen due to a lack of ****__ after death.

ATP

Muscle fibers can be classified into two major physiological classes: slow-twitch, slow oxidative fibers (Type I) and ****__ fibers (Type II).

fast-twitch, fast glycolytic (FG)

The thin filaments in muscle fibers are primarily composed of ****__.

actin

The ****__ is a specialized endoplasmic reticulum that stores and releases calcium ions for muscle contraction.

sarcoplasmic reticulum (SR)

A ****__ consists of a single motor neuron and all the muscle fibers it innervates.

motor unit

The connective tissue layer that surrounds a bundle of muscle fibers (a fascicle) is called the ****__.

perimysium

The outermost connective tissue layer that surrounds the entire muscle is called the ****__.

epimysium

The structure that anchors the thin filaments and marks the boundaries of a sarcomere is the ****__.

Z-disc

Invaginations of the sarcolemma that penetrate into the cell's interior, allowing electrical impulses to reach the deepest parts of the muscle fiber, are called ****__.

T-tubules (transverse tubules)

The theory that describes how muscle contraction occurs by the thin filaments sliding past the thick filaments, shortening the sarcomere, is called the ****__.

sliding filament theory

For short bursts of intense activity, muscles rapidly regenerate ATP using the enzyme creatine kinase to transfer a phosphate group from ****__ to ADP.

creatine phosphate