Muscle Tissue

A set of vocabulary flashcards covering terms related to muscle tissue and its functions, structures, and processes.

Skeletal Muscle

Type of muscle that is voluntary and contracts to create movement.

Cardiac Muscle

Involuntary and striated muscle found only in the heart.

Smooth Muscle

Involuntary muscle found in organs and blood vessels.

Epimysium

Connective tissue surrounding the entire muscle.

Perimysium

Connective tissue surrounding muscle fiber bundles (fascicles).

Endomysium

Connective tissue surrounding individual muscle fibers.

Tendon

Connective tissue that connects muscles to bones.

Aponeurosis

Flattened tendinous sheet that connects muscles.

Myoblasts

Cells that fuse to form muscle fibers.

Nuclei

Multiple nuclei found in skeletal muscle fibers.

Sarcoplasm

Cytoplasm of muscle cells.

Sarcoplasmic Reticulum (SR)

Membranous structure surrounding myofibrils, stores calcium ions.

Transverse Tubules (T tubules)

Invaginations of the sarcolemma that transmit action potentials.

Myofibrils

Bundles of protein filaments within a muscle fiber.

Actin

Thin filaments, primarily made of the protein actin.

Myosin

Thick filaments, primarily composed of the protein myosin.

Sarcomeres

Smallest functional units of muscle fibers responsible for contraction.

A Band

Dark area of the sarcomere where thick filaments are found.

I Band

Light area of the sarcomere that contains only thin filaments.

H Zone

Area of the A band where there are no thin filaments.

Z lines

Borders of sarcomeres where thin filaments attach.

Sliding Filament Theory

Theory explaining muscle contraction as thick and thin filaments sliding past each other.

Titin

Elastic protein that helps stabilize thick and thin filaments.

Cross-bridges

Connections formed between myosin heads and actin filaments during contraction.

Troponin

Protein that binds calcium ions and regulates muscle contraction.

Tropomyosin

Protein that covers active sites on actin to prevent interaction with myosin.

Calcium (Ca2+)

Ions that trigger muscle contraction and are stored in the sarcoplasmic reticulum.

Excitation-contraction coupling

Process linking muscle excitation to contraction.

Motor Neuron

Nerve cell that transmits signals to muscles.

Neuromuscular Junction

Synapse between a motor neuron and a muscle fiber.

Acetylcholine (ACh)

Neurotransmitter released at the neuromuscular junction.

Action Potential

Electrical impulse that leads to muscle contraction.

Repolarization

Process of restoring the membrane potential after an action potential.

Rigor Mortis

Stiffness of muscles after death due to lack of ATP.

Skeletal Muscle Contraction

Process that generates tension through the interaction of thin and thick filaments.

Calcium Channels

Membrane proteins that allow calcium ions to enter the muscle cell.

Sarcoplasmic Reticulum Release

Release of calcium into the sarcoplasm that initiates contraction.

Motor End Plate

Area of sarcolemma at the neuromuscular junction that receives ACh.

Acetylcholinesterase (AChE)

Enzyme that breaks down ACh in the synaptic cleft.

Contraction Cycle

Series of steps that lead to muscle contraction.

Energy Triggers

Require ATP to facilitate the contraction cycle.

Myofibril Organization

Arrangement of myofibrils contributes to muscle function.

M-Line

Middle line within the A band of the sarcomere.

Thick Filament Structure

Composed of myosin molecules with heads and tails.

Muscle Fiber Types

Skeletal muscle fibers can be slow or fast twitch based on function.

Structural Levels

Muscles consist of skeletal muscles, muscle fascicles, muscle fibers, myofibrils, and sarcomeres.

Fiber Shortening

Process when sarcomeres shorten and muscle pulls together.

Contraction Duration Factors

Duration influenced by neural stimulus, calcium availability, and ATP.

Relaxation Process

Ca2+ is removed, tropomyosin covers active sites, contraction stops.

Tension Production

Force exerted by muscle during contraction.

Force of Contraction Factors

Depends on muscle length, frequency of stimulation, and number of motor units activated.

Resting Length

Length of muscle when not contracted, returns passively after contraction.

Calcium Ion Role

Central to the coupling of excitation and contraction.

Neural Stimulation Importance

Triggers muscle contractions and subsequent muscle actions.

Muscle Fascicle

Bundle of muscle fibers surrounded by perimysium.

Connective Tissue Layers

Include epimysium, perimysium, and endomysium that support muscle structure.