Muscle Tissue Flashcards

Flashcards relating to muscle tissue, its types, functions, and properties.

Skeletal Muscle

Muscle that moves bones, is multi-nucleated and striated, and is under voluntary control.

Cardiac Muscle

Muscle found in the heart, pumps blood, has one nucleus, striated, and intercalated discs, and is under involuntary control.

Visceral (Smooth) Muscle

Muscle found in various organs, like the GI tract, performs various functions like peristalsis, has one nucleus and no striations, and is under involuntary control.

Create Motion

Muscles work with nerves, bones, and joints to produce body movements.

Stabilize Body Positions

Muscles maintain posture.

Store and Move Substances

Muscles store and move substances within the body using sphincters.

Move Substances

Muscles move substances by peristaltic contractions.

Generate Heat

Muscles generate heat through thermogenesis.

Electrical Excitability

The ability to respond to a stimulus (electrical or chemical) thus creating muscle action potentials.

Contractility

The ability to shorten in length creating tension pulling on it’s attachments.

Extensibility

The ability to extend or stretch without being damaged.

Elasticity

The ability to return to their original length and shape.

Fascia

Layers of dense connective tissue that surround and separate each muscle.

Epimysium

Connective tissue around each skeletal muscle.

Perimysium

Connective tissue that surrounds bundles of skeletal muscle fibers, called fascicles, within each muscle.

Endomysium

Connective tissue layer that covers each muscle cell (fiber).

Sarcolemma

The cell membrane of a muscle fiber.

Sarcoplasm

The cytoplasm of a muscle cell; it contains many mitochondria and nuclei.

Myofibrils

Active in muscle contraction, contain thick (myosin) and thin (actin, troponin, tropomyosin) filaments.

Sarcoplasmic Reticulum (SR)

Endoplasmic reticulum of a muscle cell

Sarcomeres

Repeating units that make up myofibrils; extends from one Z line to the next.

I bands (light bands)

Made up of actin filaments, which are anchored to Z lines.

A bands (dark bands)

Made up of overlapping thick and thin filaments.

H zone

Consists of myosin filaments only; located in the center of the A band.

M line

Consists of proteins that hold myosin filaments in place; found in the center of the H zone.

Z discs

Narrow, plate-shaped regions of dense material that separate one sarcomere from the next.

Contractile proteins

Proteins that generate force during muscle contractions (Myosin, Actin).

Tropomyosin

Regulatory protein that is a component of thin filament; when skeletal muscle fiber is relaxed, tropomyosin covers myosin-binding sites on actin molecules, thereby preventing myosin from binding to actin.

Troponin

Regulatory protein that is a component of thin filament; when calcium ions (Ca2+) bind to troponin, it changes shape; this conformational change moves tropomyosin away from myosin-binding sites on actin molecules, and muscle contraction subsequently begins as myosin binds to actin.

Neuromuscular Junction

A synapse between a motor neuron and a muscle fiber that it regulates.

Neurotransmitters

Chemicals released at synapse by a motor neuron to communicate with muscle fiber.

Motor End Plate

Specialized region of muscle fiber membrane in NMJ that contains receptors for neurotransmitters.

Thick filament

a group of myosin molecules forms

sliding filament model of muscle contraction

According to this model, during muscle contraction, a myosin head attaches to a binding site on the actin filament, forming a cross-bridge.

Rigor Mortis

State of rigidity in muscles occurring 3-4 hours after death due to calcium leakage and decreased ATP.

ATP

Muscles have 3 ways to produce

Creatine Phosphate (CP)

Creatine kinase catalyzes the transfer of a phosphate group from CP to ADP to rapidly yield ATP

Muscle fatigue

the inability to maintain force of contraction after prolonged activity

Central Fatigue

Occurs due to changes in the central nervous system and generally results in cessation of exercise.

intercalated discs

Cardiac muscle has the same arrangement as skeletal muscle, but also has

Muscle Tone

the alternating, involuntary activation of small groups of motor units in a muscle

Isotonic Contractions

tension is constant while muscle length changes

Isometric Contractions

muscle contracts but does not change length