Muscles and Muscle Tissue

This flashcard set covers key terms and concepts related to muscle and muscle tissue, including types of muscle tissue, characteristics, contraction mechanisms, energy sources, and muscle fiber types.

Muscle Tissue

One of the four primary tissue types specialized to allow movement.

Skeletal Muscle

Muscle attached to bones, long and cylindrical in shape, multinucleate, striated, and under voluntary control.

Cardiac Muscle

Muscle that makes up the heart, short and branched cells, with a single central nucleus, striated, and under involuntary control.

Smooth Muscle

Muscle found in the walls of hollow organs, spindle-shaped cells with a single nucleus, no striations, and under involuntary control.

Excitability

The ability of muscle tissue to receive and respond to a stimulus.

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 return to its original length after being stretched.

Epimysium

Dense irregular connective tissue surrounding the entire muscle.

Perimysium

Fibrous connective tissue surrounding fascicles, or bundles of muscle fibers.

Endomysium

Areolar connective tissue surrounding each muscle fiber.

Sarcolemma

The plasma membrane of a muscle fiber.

Myofibrils

Rod-like structures composed of protein myofilaments within muscle fibers.

Sarcomere

The smallest functional unit of skeletal muscle, defined as the region between two successive Z discs.

Cross Bridge Cycling

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

Rigor Mortis

Condition where muscles stiffen after death due to calcium influx and lack of ATP, causing cross bridges to remain bound.

Isotonic Contraction

Muscle changes length while tension remains constant; includes concentric and eccentric contractions.

Isometric Contraction

Muscle length remains unchanged while muscle tension increases.

Energy for Contraction

ATP is needed for muscle contraction to move and detach cross bridges and pump calcium back into the sarcoplasmic reticulum.

Glycolysis

Anaerobic process that breaks down glucose into pyruvic acid, yielding ATP.

Aerobic Respiration

Mitochondrial process that requires oxygen to produce ATP, CO2, and H2O.

Motor Unit

The combination of one motor neuron and all the muscle fibers it supplies.

Muscle Twitch

The response of a motor unit to a single action potential from a motor neuron.

Graded Muscle Response

The ability of muscles to vary the amount of force produced.

Recruitment

The activation of additional motor units to increase contractile strength.

Muscle Tone

Continuous partial contraction of muscles, important in stabilizing joints and maintaining posture.

Fast Glycolytic Fibers

Muscle fiber type that produces fast, powerful contractions but fatigues quickly, primarily using anaerobic glycolysis.

Slow Oxidative Fibers

Muscle fiber type that produces low power contractions over long periods, primarily using aerobic respiration.