HUM - Chapter 10 Muscle Tissue

Functions of Muscular Tissue

1. Producing body movements 2. Stabilizing body positions 3. Storing and moving substances within the body 4. Generating heat

Muscular Atrophy

A decrease in the size of individual muscle fibers as a result of progressive loss of myofibrils

Myopathy

A disease or disorder of the skeletal muscle tissue itself

Muscular dystrophy

A group of inherited muscle-destroying diseases that causes progressive degeneration of skeletal muscle fibers

Perimysium

A layer of dense irregular connective tissue, surrounds groups of 10 to 100 or more muscle fibers separating them into bundles or muscle fascicles

I band

A lighter area that contains the rest of the thin filaments but no thin filament

Nebulin

A long, non-elastic protein that wraps around the entire length of the thin filament during development

Somatic Motor Neuro

A neuron that stimulates skeletal muscles fiber to contract

Synapse

A region where communication occurs between two neurons, or between a neuron and a target cell

Calmodulin

A regulatory protein that binds to Ca2+ in the sarcoplasm

Muscle Tone

A small amount of tautness or tension in muscle due to weak, involuntary contractions of its motor units

Creatine

A small, amino-acid like molecules synthesized in the liver, kidneys, and pancreas then transported to the muscle fibers

Motor Unit

A somatic motor neuron plus all the skeletal muscle fibers it stimulates

Fibrillation

A spontaneous contraction of a single muscle fiber that is not visible under the skin but can be recorded by electromyography

Fused tetanus

A sustained contraction in which individual twitches cannot be detected

Electromyography (EMG)

A thin needle, recording device, is placed through the skin into a muscle; need is connected by a wire to a screen

Contractility

Ability to contract forcefully when stimulated by a nerve impulse

Anaerobic training

Activities stimulate synthesis of muscle proteins and result in increased muscle size

Rigor Mortis

After death, cellular membranes become leaky

Exercise-Induced Muscle Damage

After intense exercise, damage can included torn sarcolemmas, damaged myofibrils, disrupted Z discs

Slow oxidative fibers

Appear dark red due to large amounts due to large amounts of myoglobin and many blood capillaries

Sacromeres

Basic Functional unit of a myofibril

Recovery Oxygen Uptake

Better term for oxygen debt after exercise

α-actinin

Bind to each actin molecule of th thin filament and to the titin

Twitch contraction

Brief contraction of all muscle fibers in a motor unit in response to a single action potential

Aerobic training

Builds endurance for prolonged activities

Contraction period

Ca2+ binds to troponin Myosin-binding sites on actin are exposed Cross-bridges form

Relaxation phase

Ca2+ is actively transported back into the SR, myosin-binding sites are covered by tropomyosin, myosin heads detach from actin, tension in the fiber decreases

Myofibrils

Contractile organelles of skeletal muscle, gives skeletal muscle their striated appearance

Sarcoplasm

Cytoplasm of a muscle fiber that contains a large amount of glycogen

Hypotonia

Decreased or lost muscle tone

Electrodiagnostic Medicine

Diagnosis of neuromuscular disorders

Terminal cisterns

Dilated end sacs of the sarcoplasmic reticulum that butt against the T tubules from both sides

A band

Extends the entire length of the thick ligament

Rigidity

Increased muscle tone where reflexes are not affected

Sarcoplasmic reticulum

Fluid-filled system of membranous sacs that encircle each myofibril

Myomesin

Form the M line, binds to titin and connects adjacent thick filaments to one another

Cardiac Muscle

Forms most of the walls of the heart

Visceral Smooth Muscle Tissue

Found in skin and tubular arrangements that form part of the walls of small arteries, veins, and hollow organs: stomach, intestines, uterus, urinary bladder

Hypertonia

Increased muscle tone, expressed two ways

Sclerotome

Gives rise to the vertebrae and ribs

Multi-unit Smooth Muscle Tissue

Individual fibers with its own motor neuron terminal and few gap junctions between neighboring fibers

Refractory period

When a muscle temporarily loses their excitability and cannot respond for a time

Zone of overlap

Where the thick and thin filaments lie side by side

Interval training

a workout regimen that incorporates both types of training

Fast oxidative-glycolytic fibers

Largest fibers

Dystrophin

Links think filaments of the sarcomere to integral membrane proteins of the sarcolemma, which are attached to proteins in the connective tissue extracellular matrix that surrounds muscle fibers

Smooth muscle Tissue

Located in the walls of hollow internal structures

ATP Hydrolysis

Myosin head includes an ATP-binding site that functions as an ATPase

Power Stroke

Myosin head pivots, changing position as it pulls the think filament past the thick filament toward the center of the sarcomere, generating tension

Acetylcholine (ACh)

Neurotransmitter in the synaptic vesicles that is released at the NMJ

Anabolic Steroids

Synthetic variations of testosterone

Cramp

Painful spasmodic contraction

Isotonic Contraction

Tension developed in the muscle remains almost constant while the muscle changes its length

Isometric contraction

Tension generated is not enough to exceed the resistance of the object being moved, the muscle doesn't change its length

Concentric isotonic contraction

Tension is great enough to overcome the resistance of the object to be moved

Neuromuscular Disease

Problems with somatic motor neurons, neuromuscular junctions, and muscle fibers

Myogram

Record of a muscle twitch

Myoglobin

Red-colored protein, only found in muscle, binds oxygen when needed by the mitochondria for ATP production

Motor End Plate

Region of the sarcolemma opposite the synaptic end bulbs

Tropomyosin and Troponin

Regulatory proteins that are part of the thin filaments

Tremor

Rhythmic, involuntary, purposeless contraction that produces quivering or shaking movement

Z disc

Separates one sarcomere from the next, passes through the center of each I band

Synaptic Cleft

Separates two cells by a small gap

Myotome

Skeletal muscles of the trunk and limbs

Filaments

Smaller protein structures within the myofibrils

Tic

Spasmodic twitching made involuntary by muscles that are ordinarily under voluntary control

Wave summation

Stimuli arriving at different times causing a larger contraction

Spasm

Sudden involuntary contraction of a single muscle in a large group of muscles

Unfused tetanus

Sustained but wavering contraction

motor unit recruitment

The number of active motor units increases

Strength Training

The process of exercising with progressively heavier resistance for the purpose of strengthening the MSK system

Neuromuscular junciton (NMJ)

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

Eccentric isotonic contraction

The tension exerted by the myosin cross bridges resists movement of a load and slows the lengthening process

Myosin

Thick filaments and function as a motor protein in all three types of muscle tissue

Junctional Folds

deep grooves in the motor end plate that provide a large surface area for ACh

Hypertrophy

enlargement of existing cells

dermatomal mesenchyme

forms the connective tissues, including the dermis of the skin and subcutaneous tissue

Smooth Muscle Tissue

involuntary, non-striated

Epimysium

outer layer, encircling the entire muscle, dense irregular connective tissue

Extensibility

the ability to be stretched or extended, within limits; without being damaged

electrical excitability

the ability to respond to certain stimuli by producing electrical signals

Synaptic end bulbs

the neural part of the NMJ

Titin

the third most plentiful protein in skeletal muscle

acetylcholine receptors

within the motor end plate, where transmembrane proteins with ACh specifically bind

Hyperplasia

Increase in the number of fibers

Spasticity

Increase muscle tone associated with an increase in tendon reflexes and pathological reflexes (Babinski)

Stress-relaxation response

Allows smooth muscle to undergo great changes in length while retaining the ability to contract effectively

Fasciculation

An involuntary, brief twitch of an entire motor unit that is visible under the skin

Detachment of myosin from actin

At the end of the power stroke, the crossbridge remains firmly attached to actin until it binds another molecule of ATP.

M line

At the middle of the sarcomere

Myasthenia gravis

Autoimmune disease that causes chronic, progressive damage of the NMJ

Central fatigue

Caused by changes in the central nervous system

H band

Center of each A band that contains thick filament but no think filaments

Spastic paralysis

Certain disorders of the nervous system and electrolyte disturbances in which partial paralysis in which the muscle exhibits spasticity

Fibromyalgia

Chronic, painful, nonarticular rheumatic disorder that affects the fibrous connective tissue components of muscles, tendons, and ligaments

Attachment of myosin to actin

Energized myosin head attaches to the myosin-binding site on actin and releases the previously hydrolyzed phosphate group

flaccid paralysis

Loss of muscle tone due to disruptions in the balance of electrolytes where a loss of muscle tone, loss or reduction of tendon reflexes, atrophy and degeneration of muscles

Fast glycolytic fibers

Low myoglobin content, few blood capillaries, appear more white in color

nerve conduction velocity tests (NCV)

Measure the speed of nerve impulses conducted through nerves outside the brain and spinal cord

Synaptic vesicles

Membrane enclosed sacs

Skeletal Muscle Tissue

Most skeletal muscles move the bones of the skeleton

Muscular Hypertrophy

Muscle growth after birth that occurs by enlargement of existing muscles fibers

Oxygen debt

The added oxygen, over and above the resting oxygen consumption that the body needs after exercise

Latent period

The brief delay between the application of the stimulus and the beginning of a contraction

Neurotransmitters

The chemical messenger that allows one cell to communicate with the next cell

Axon Terminal

The end of the motor neuron

Muscle Fatigue

The inability of a muscle to maintain force of contraction after prolonged activity

Elasticity

ability of muscular tissue to return to its original length and shape after contraction of extension