Chapter 11 - Tegrity (1)

Functions of Muscles

Movement of body parts and organ contents, maintain posture, communication, control openings, and heat production.

Characteristics of Muscle

Includes responsiveness (excitability), conductivity, contractility, extensibility, and elasticity.

Skeletal Muscle

Muscle fibers that are voluntary, exhibit striations, and can be as long as 30 cm.

Myofilament

A component of muscle fibers involved in contraction, includes actin and myosin.

Sarcolemma

The plasma membrane surrounding a muscle fiber.

Neuromuscular Junction

The synapse between a motor neuron and a skeletal muscle fiber, where ACh is released.

Acetylcholine (ACh)

A neurotransmitter released at the neuromuscular junction to stimulate muscle contraction.

Excitation-Contraction Coupling

The process linking the action potential in muscle fibers to muscle contraction.

Cross-Bridge

The connection formed when myosin heads attach to binding sites on actin filaments.

Rigor Mortis

The stiffening of the body after death due to calcium release and lack of ATP.

Muscle Twitch

A single brief contraction resulting from one action potential.

Isometric Contraction

Muscle contraction without change in length.

Isotonic Contraction

Muscle contraction resulting in movement and changing length.

Slow-Twitch Fibers (Type I)

Muscle fibers with high endurance, rich in mitochondria and myoglobin, used for aerobic activities.

Fast-Twitch Fibers (Type II)

Muscle fibers that are more powerful and fatigue faster, adapted for anaerobic activities.