Human Anatomy and Physiology: Muscles and Muscle Tissue

This set of flashcards covers terms and definitions related to muscle tissue types, muscle functions, cellular structures of muscles, and related muscle physiology concepts.

Skeletal Muscle

Skeletal muscle tissue is packaged into organs attached to bones and skin, contains striations, and is voluntarily controlled.

Cardiac Muscle

Cardiac muscle is striated and involuntary, primarily found in the heart, and contracts at a steady rate regulated by intrinsic pacemaker.

Smooth Muscle

Smooth muscle tissue is nonstriated and involuntary, found in the walls of hollow organs, such as the stomach and urinary bladder.

Excitability

The ability of muscle tissue to receive and respond to stimuli.

Contractility

The ability of muscle tissue to shorten forcibly when stimulated.

Extensibility

The ability of muscle tissue to be stretched.

Elasticity

The ability of muscle tissue to recoil to its resting length.

Cross Bridge Cycle

The sequence of events during which myosin heads pull thin filaments toward the center of the sarcomere.

Action Potential (AP)

A neural impulse that travels down the axon and causes muscle contraction.

Neuromuscular Junction (NMJ)

The synapse or junction of the axon terminal and muscle fiber, where the neurotransmitter acetylcholine is released.

T Tubules

Tube-like structures that penetrate into muscle fibers, allowing nerve impulses to stimulate muscle contraction.

Sarcoplasmic Reticulum (SR)

A network of smooth endoplasmic reticulum surrounding myofibrils in muscle fibers, regulating intracellular calcium levels.

Myofibrils

Rod-like units within muscle fibers made up of sarcomeres and contractile proteins.

Striations

The alternating dark and light bands of skeletal and cardiac muscle fibers visible under a microscope.

Troponin

A regulatory protein bound to tropomyosin that helps control muscle contraction by binding calcium ions.

Tropomyosin

A regulatory protein that blocks myosin-binding sites on actin in a relaxed muscle.

Duchenne Muscular Dystrophy (DMD)

A severe form of muscular dystrophy caused by a defective gene for dystrophin.

Rigor Mortis

A state of muscle rigidity that occurs after death due to depleted ATP levels.

Motor Unit

A motor neuron and all the muscle fibers it innervates; it serves as the functional unit of muscle contraction.

Graded Muscle Response

The varying strength of muscle contraction achieved by changing the frequency or strength of stimulation.

Somatic Motor Neurons

Neurons that stimulate skeletal muscle fibers for contraction.

Elastic Filament (Titin)

A protein that holds thick filaments in place and helps muscle fibers recoil after stretching.

Calmodulin

A protein that binds calcium ions in smooth muscle, replacing troponin.

Oxidative Fibers

Muscle fibers that use aerobic pathways for ATP synthesis.

Glycolytic Fibers

Muscle fibers that primarily use anaerobic glycolysis for ATP production.