The Muscular System

Flashcards containing definition of muscular system from chapter 8.

Myology

The scientific study of muscles.

What are the three types of muscular tissue?

Skeletal muscle, cardiac muscle, and smooth muscle.

Skeletal Muscle Tissue

Mostly attached to bones, striated, and voluntary.

Cardiac Muscle Tissue

Forms most of the wall of the heart, striated, and involuntary.

Smooth Muscle Tissue

Located in viscera, nonstriated, and involuntary.

What are the five key functions of muscular tissue?

Producing body movements, stabilizing body positions, regulating organ volume, moving substances within the body, and producing heat.

Muscle Fibers

Skeletal muscles are separate organs composed of hundreds to thousands of cells called:

Epimysium

Connective tissue covering an entire muscle.

Perimysium

Connective tissue covering fascicles.

Endomysium

Connective tissue covering individual muscle fibers.

Tendons

Extensions of connective tissue beyond muscle fibers that attach the muscle to bone.

Sarcolemma

Plasma membrane that covers the skeletal muscle

Transverse Tubules (T-tubules)

Tunnel in from the surface toward the center of each muscle fiber.

Sarcomeres

Functional units that filaments are arranged in

Myosin

Thick filaments consist of:

Actin, Tropomyosin, and Troponin

Thin filaments are composed of:

Z discs

Sarcomeres are separated from one another by zig-zagging zones of dense protein material called:

A band

A darker area within each sarcomere that extends the entire length of the thick filaments.

H zone

A narrow zone at the center of each A band, which contains only the thick filaments.

I band

A lighter-colored area to either side of the A band, which contains the rest of the thin filaments but no thick filaments.

Motor Neuron

The neuron which delivers an electrical signal called a muscle action potential to a skeletal muscle fiber so it can contract.

Motor Unit

A single motor neuron along with all the muscle fibers it stimulates

Neuromuscular Junction (NMJ)

The synapse between a motor neuron and a skeletal muscle fiber.

Acetylcholine (ACh)

Released from synaptic vesicles; diffuses across the synaptic cleft and binds to ACh receptors, initiating a muscle action potential.

Acetylcholinesterase

Breaks down ACh.

Sliding-Filament Mechanism

The sliding of filaments and shortening of sarcomeres that cause the shortening of muscle fibers.

What two things are needed for muscle contraction?

Ca2+ and energy, in the form of ATP

Name the 4 steps of the contraction cycle:

1. Splitting ATP 2. Forming cross-bridges 3. Power stroke 4. Binding ATP & detaching

List the three sources for ATP production:

Creatine phosphate, anaerobic glycolysis, and aerobic respiration.

Creatine Phosphate

Provides enough energy for muscles to contract maximally for about 15 seconds.

Anaerobic Glycolysis

Glucose is converted to pyruvic acid in the reactions of glycolysis, which yield two ATPs without using oxygen and can provide enough ATP for about 2 minutes of maximal muscle activity.

Aerobic Respiration

Mitochondrial reactions that require oxygen to produce ATP; yields about 36 molecules of ATP from each glucose molecule.

Muscle Fatigue

The inability of a muscle to contract forcefully after prolonged activity.

Recovery Oxygen Uptake

Elevated oxygen use after exercise.

Twitch Contraction

A brief contraction of all of the muscle fibers in a motor unit in response to a single action potential in its motor neuron.

Myogram

A record of a contraction.

latent period, contraction period, and a relaxation period

A myogram consists of:

Wave Summation

The increased strength of a contraction that occurs when a second stimulus arrives before the muscle has completely relaxed after a previous stimulus.

Motor Unit Recruitment

The process of increasing the number of active motor units.

List the three types of skeletal muscle fibers:

Slow oxidative (SO) fibers, fast oxidative-glycolytic (FOG) fibers, and fast glycolytic (FG) fibers.

The order in which motor units of a muscle are recruited:

first SO fibers, then FOG fibers, and finally FG fibers

Which type of muscle tissue contracts when stimulated by its own autorhythmic fibers?

Cardiac

Smooth Muscle Tone

A state of continuous partial contraction of smooth muscle tissue.

Origin

The attachment to the stationary bone

Insertion

The attachment to the movable bone

Prime Mover (Agonist)

Produces the desired action.

Antagonist

Produces an opposite action.

Synergist

Assists the prime mover by reducing unnecessary movement.

Fixator

Stabilizes the origin of the prime mover so that it can act more efficiently.

Rectus

Parallel to midline.

Transverse

Perpendicular to midline.

Oblique

Diagonal to midline.

Maximus

Largest.

Minimus

Smallest.

Longus

Longest.

Latissimus

Widest.

Longissimus

Longest.

Magnus

Large.

Major

Larger.

Minor

Smaller.

Vastus

Great.

Deltoid

Triangular.

Trapezius

Trapezoid.

Serratus

Saw-toothed.

Rhomboid

Diamond-shaped.

Orbicularis

Circular.

Pectinate

Comblike.

Piriformis

Pear-shaped.

Platys

Flat.

Quadratus

Square.

Gracilis

Slender.

Flexor

Decreases joint angle.

Extensor

Increases joint angle.

Abductor

Moves bone away from midline.

Adductor

Moves bone closer to midline.

Levator

Produces superior movement.

Depressor

Produces inferior movement.

Supinator

Turns palm anteriorly.

Pronator

Turns palm posteriorly.

Sphincter

Decreases size of opening.

Tensor

Makes a body part rigid.

Biceps

Two origins.

Triceps

Three origins.

Quadriceps

Four origins.