Functional Anatomy of Skeletal Muscle Tissue

These flashcards cover key vocabulary and concepts related to the anatomical and physiological aspects of skeletal muscle tissue.

Skeletal Muscle Tissue

Muscle tissue primarily responsible for voluntary movements, composed of skeletal muscle fibers.

Muscle Fiber

A single muscle cell that contracts in response to stimulation.

Neuromuscular Junction

The synapse where motor neurons communicate with skeletal muscle fibers.

Epimysium

A dense sheath of collagen fibers surrounding a muscle.

Perimysium

A fibrous layer that divides muscles into compartments and surrounds muscle fascicles.

Endomysium

A thin layer of areolar connective tissue that surrounds each individual muscle fiber.

Myofibrils

Cylindrical structures made up of actin and myosin that facilitate muscle contraction.

Sarcomere

The functional unit of a myofibril, defined by Z lines, responsible for muscle contraction.

Thin Filament

Major protein filament in muscle fibers, primarily composed of actin.

Thick Filament

Major protein filament in muscle fibers, primarily composed of myosin.

Z Lines

Structures that demarcate the boundaries of sarcomeres.

I Band

The light band in a sarcomere containing only thin filaments.

A Band

The dark band in a sarcomere containing thick filaments and overlapping thin filaments.

M Line

The center of the A band, where thick filaments meet.

H Band

The lighter region within the A band that contains only thick filaments.

Sarcolemma

The plasma membrane of a skeletal muscle fiber.

Sarcoplasmic Reticulum

Smooth endoplasmic reticulum in muscle cells that stores calcium ions.

Transverse Tubules (T Tubules)

Extensions of the sarcolemma that penetrate into the muscle fiber, facilitating electrical signals.

Calcium Ions

Ions that play a crucial role in muscle contraction by binding to troponin.

Excitation-Contraction Coupling

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

Action Potential

An electrical impulse that stimulates muscle contraction.

Tendon

A fibrous connective tissue that attaches muscle to bone.

Aponeurosis

A flat sheet of connective tissue that connects muscles to each other or to bones.

Motor Neuron

A neuron that transmits impulses to skeletal muscle fibers.

Acetylcholine (ACh)

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

Acetylcholinesterase (AChE)

An enzyme that breaks down acetylcholine in the synaptic cleft.

Muscle Contraction Cycle

The series of steps that lead to the shortening of muscle fibers.

Cross-Bridge Cycle

The process of myosin heads binding to actin filaments, pulling them, and detaching.

Power Stroke

The action of myosin heads pulling actin filaments toward the center of the sarcomere.

ATP (Adenosine Triphosphate)

The primary energy carrier in cells that fuels muscle contractions.

Creatine Phosphate

A high-energy molecule stored in muscles used to regenerate ATP quickly.

Glycolysis

The anaerobic breakdown of glucose to produce ATP.

Muscle Fatigue

A decline in the ability of a muscle to generate force due to prolonged activity.

Muscle Hypertrophy

The increase in muscle size due to repeated stimulation and training.

Muscle Atrophy

The decrease in muscle size and strength due to disuse or neurogenic causes.

Motor Unit

A motor neuron and all the muscle fibers it innervates.

Muscle Tone

The constant low-level tension maintained by muscles.

Treppe

The staircase phenomenon where muscle tension increases with successive contractions.

Wave Summation

The addition of muscle twitches when stimulation occurs before relaxation.

Incomplete Tetanus

A state of sustained muscle contraction with partial relaxation.

Complete Tetanus

A sustained muscle contraction with no relaxation period.

Isotonic Contraction

A muscle contraction where tension remains constant while muscle length changes.

Isometric Contraction

A muscle contraction where muscle length remains unchanged, but tension increases.

Cori Cycle

The process of converting lactate produced in muscles back to glucose in the liver.

Oxygen Debt

The amount of oxygen required to restore normal conditions in muscles after exertion.

Myofibrils

The subunits found in muscle fibers which are made of myofilaments.

F-Actin

Filamentous actin, a polymerized form of G-actin that makes up the thin filaments.

Tropomyosin

A protein that blocks the myosin binding sites on actin when the muscle is relaxed.

Troponin

A protein complex that binds calcium ions and promotes muscle contraction.

Titin

A protein that connects thick filaments to Z lines and helps maintain the structure of the sarcomere.