Untitled Flashcards Set

Skeletal Muscle

Striated, voluntary muscle attached to bones, responsible for movement and posture.

Cardiac Muscle

Striated, involuntary muscle found in the heart, responsible for pumping blood.

Smooth Muscle

Non-striated, involuntary muscle found in internal organs and blood vessels, responsible for moving substances.

Myofiber

A single muscle cell containing multiple myofibrils.

Myofibrils

Chains of sarcomeres, which are the contractile units of muscle.

Sarcomere

The functional unit of muscle, made up of thick (myosin) and thin (actin) filaments.

Sliding Filament Theory

The process where myosin pulls actin filaments inward to shorten the sarcomere.

Neuromuscular Junction (NMJ)

The synapse between a motor neuron and a muscle fiber where muscle activation occurs.

Acetylcholine (ACh)

A neurotransmitter released at the NMJ that binds to receptors, initiating muscle contraction.

Cross-Bridge Cycle

The series of events where myosin binds to actin, leading to muscle contraction.

Isometric Contraction

Muscle contracts but does not shorten; example: holding a plank.

Isotonic Contraction

Muscle contracts and shortens; example: lifting a weight.

Eccentric Contraction

Muscle lengthens under tension; example: lowering a dumbbell.

Concentric Contraction

Muscle shortens under tension; example: raising a dumbbell.

Motor Unit

A motor neuron and all the muscle fibers it controls.

Slow Oxidative Fiber (Type I)

Slow-twitch muscle fibers; high endurance, primarily use aerobic respiration.

Fast Glycolytic Fiber (Type IIx)

Fast-twitch muscle fibers; generate power quickly, fatigue rapidly, use glycolysis.

Single-Unit Smooth Muscle

Smooth muscle where cells contract together via gap junctions; example: intestines.

Multi-Unit Smooth Muscle

Smooth muscle where cells contract independently; example: iris, piloerector muscles.