Chapter 10.1-10.2 Muscular Tissue

Skeletal Muscle Tissue

Muscle that moves bones of the skeleton voluntarily, striated, multinucleated.

Cardiac Muscle Tissue

Muscle found in the heart wall, striated, uninucleate, contracts involuntarily.

Smooth Muscle Tissue

Non-striated muscle found in walls of organs, blood vessels; moves things involuntarily.

Striated Muscle

Muscle tissue with alternating light and dark protein bands.

Multinucleated

Having multiple nuclei in a single cell.

Autorhythmicity

Ability of cardiac muscle to contract rhythmically without external stimuli.

Extensibility

The ability of muscle tissue to stretch within limits without being damaged.

Elasticity

The ability of muscle tissue to return to its original length and shape after contraction or extension.

Contractility

The ability of muscle tissue to contract forcefully when stimulated.

Epimysium

Outer layer of connective tissue surrounding the entire muscle.

Perimysium

Connective tissue that surrounds groups of muscle fibers, forming muscle fascicles.

Endomysium

Connective tissue that separates individual muscle fibers from one another.

Sarcomere

Basic functional unit of a myofibril, extends from Z disc to Z disc.

Myofibrils

Contractile organelles found in skeletal muscle fibers.

Sarcoplasmic Reticulum (SR)

Membranous sacs that encircle myofibrils, releasing calcium to trigger muscle contraction.

Thick Filaments

Muscle protein filaments made primarily of myosin.

Thin Filaments

Muscle protein filaments made primarily of actin.

Actin-binding Site

Location on myosin head that can attach to actin.

ATP Binding Site

Site on myosin head that binds ATP, enabling muscle contraction.

Troponin

Protein that holds tropomyosin in place and regulates muscle contraction.

Tropomyosin

Protein that blocks myosin-binding sites on actin in relaxed muscle.

Z Disc

Dense protein structure that separates sarcomeres.

A Band

Darker region of the sarcomere that contains thick filaments.

I Band

Lighter region of the sarcomere that contains only thin filaments.

H Band

Center of the A band containing only thick filaments.

M Line

Support proteins holding thick filaments together at the center of the H band.

Fibromyalgia

Chronic disorder characterized by widespread pain and tenderness in muscles and connective tissues.

Muscle Hypertrophy

Enlargement of existing muscle fibers due to increased myofibrils.

Muscle Atrophy

Decrease in size of muscle fibers due to loss of myofibrils.

Denervation Atrophy

Irreversible muscle shrinkage due to disruption of nerve supply.

Titin

Structural protein that stabilizes the thick filament and maintains central location of A bands.

Nebulin

Non-elastic protein that anchors thin filaments to Z discs.

Dystrophin

Protein that links thin filaments of the sarcomere to the surrounding connective tissue.

Sarcolemma

Plasma membrane of a muscle fiber.

T-tubules

Invaginations (folds) of the sarcolemma that help transmit action potentials into the muscle fiber.

Sphincters

Ringlike smooth muscles that regulate the outflow of contents in hollow organs.

Thermogenesis

Production of heat by muscle contraction.

Somatic Motor Neurons

Nerves that stimulate skeletal muscle contraction.

Muscle Fiber

Long, cylindrical cells (myocytes) that make up skeletal muscles.

Dystrophy

Muscle weakness or wasting due to genetic or acquired conditions.

Intercalated Disks

Structures that connect cardiac muscle cells allowing coordinated contraction.

Blood Capillaries

Microscopic vessels that supply blood to muscle fibers, bringing oxygen and nutrients.

Myoglobin

Red protein that binds oxygen in muscle fibers, releasing it when needed.

Calcium Release

Critical step in muscle contraction triggered by action potentials.

Chemical Stimuli

Substances like neurotransmitters that trigger muscle contractions.

Electrical Excitability

Ability of muscle tissue to respond to stimuli with action potentials.