Muscle Structure and Function

These flashcards cover key terms and definitions related to muscle structure and function, including types of muscle tissue, essential proteins involved in contraction, and relevant physiological processes.

Skeletal Muscle

Muscle tissue responsible for locomotion, controlled voluntarily, striated appearance, and multinucleated cells.

Cardiac Muscle

Involuntary muscle found in the heart, striated and branched, controlled by the SA node.

Smooth Muscle

Involuntary muscle found in the walls of hollow organs, not striated, spindle-shaped cells.

Myofibril

Contractile element of muscle fiber composed of sarcomeres, contains thick (myosin) and thin (actin) filaments.

Sarcomere

The functional unit of muscle contraction, defined as the region between two Z discs.

Actin

Thin filament protein involved in muscle contraction, has binding sites for myosin heads.

Myosin

Thick filament protein that interacts with actin to facilitate muscle contraction.

Troponin

Regulatory protein that binds calcium and moves tropomyosin away from actin's binding sites.

T Tubules

Invaginations of the sarcolemma that conduct electrical impulses into the muscle fiber.

Neuromuscular Junction

Area where motor neuron meets muscle fiber, facilitating signal transmission for muscle contraction.

Acetylcholine

Neurotransmitter released at the neuromuscular junction that binds to receptors on muscle fibers.

Striation

Banding pattern seen in skeletal and cardiac muscle due to the arrangement of actin and myosin.

Epimysium

Connective tissue sheath surrounding an entire muscle.

Perimysium

Connective tissue surrounding a group of muscle fibers, forming a fascicle.

Endomysium

Connective tissue surrounding individual muscle fibers.

Crossbridge

The attachment of myosin heads to binding sites on actin filaments during muscle contraction.

Sarcoplasmic Reticulum

Specialized endoplasmic reticulum in muscle fibers that stores and regulates calcium.

Striated Muscle

Muscle that appears striped due to alternating light and dark bands from myofibrils.

Unit of Muscle Contraction

Muscle fibers contract via sarcomeres shortening, due to the sliding filament mechanism.

Muscle Fatigue

Decreased ability of muscle to generate force, often due to depletion of energy sources.

Muscle Belly

The fleshy part of the muscle that contracts and comes between the tendons.

Origin and Insertion

Origin is the attachment that doesn't move; insertion is where the muscle attaches and moves.

Strains

Injury resulting from overstretching or tearing muscle fibers.

Muscle Actions

Movements created by muscles contracting, including flexion, extension, abduction, and adduction.

Mitochondria

Organelles in muscle cells that produce ATP necessary for muscle contractions.

ATP

Energy currency of the cell, necessary for muscle contractions and relaxation.

Rigor Mortis

Stiffening of muscles after death due to lack of ATP, preventing crossbridge detachment.