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muscular tissue
anatomy 1
| Question | Answer |
|---|---|
| Myology | The scientific study of muscles. |
| Skeletal Muscle Tissue | An organ specialized for contraction, composed of striated muscle fibers(cells), supported by connective tissue, attached to a bone by a tendon or an aponeurosis, and stimulated by somatic motor neuron. |
| Cardiac Muscle Tissue | Forms most of the heart wall.Striated but its action is involuntary. |
| Autorhythmicity | The heart beats because it has a pacemaker that initiates each contraction. A built in rhythm.Several hormones and neurotransmitters can adjust heart rate by speeding or slowing the pacemaker. |
| Smooth Muscle Tissue | Located in the walls of hollow internal structures, such as blood vessels, airways, and most organs in the abdominopelvic cavity. Also found in the skin, attached to hair follicles. |
| Producing Body Movements | Movements of the whole body such as walking and running,and localized movements such as grasping a pencil or nodding the head as a result of muscular contractions, rely on the integrated functioning of skeletal muscles, bones, and joints. |
| Stabilizing Body Positions | Skeletal muscle contractions stabilize joints and help maintain body positions such as standing or sitting. Postural muscles contract continuously when you are awake: for example, sustained contractions of your neck muscles hold your head upright. |
| Storing and Moving Substances Within The Body | Storage is accomplished by sustained contractions of ringlike bands of smooth muscle called sphincters,which prevent outflow of the contents of a hollow organ. |
| Thermogenesis | As muscular tissue contracts,it produces heat. |
| Electrical Excitability | A property of both muscle and nerve cells,the ability to respond to certain stimuli by producing electrical signals called action potentials. |
| Contractility | The ability of muscular tissue to contract forcefully when stimulated by an action potential. |
| Extensibility | The ability of muscular tissue to stretch without being damaged. |
| Elasticity | The ability of muscular tissue to return to its original length and shape after contraction or extension. |
| Muscle Fibers | Each of your skeletal muscles is a separate organ composed of hundreds to thousands of cells. |
| Subcutaneous Layer | Hypodermis- Separates muscle from skin,is composed of areolar connective tissue and adipose tissue. |
| Epimysium | Connective tissue- the outermost layer,encircling the entire muscle. |
| Perimysium | Surrounds groups of 10-100 or more muscle fibers,seperating them into bundles called fascicles. |
| Fascicles | The Seperation of muscle fibers, large enough to be seen with the naked eye. |
| Endomysium | Penetrating the interior of each fascicle and separating individual muscle fibers from one another.A thin sheath of areolar connective tissue. |
| Tendon | A cord of dense regular connective tissue composed of parallel bundles of collagen fibers that attach a muscle to the periosteum of a bone. |
| Aponeurosis | When the connective tissue elements extend as a broad, flat layer (tendon) |
| Tendon (synovial) Sheats | Certain Tendons,especialy those of the wrist and ankle are enclosed by tubes of fibrous connective tissue. |
| Hypertrophy | An enlargement of existing muscle fibers |
| Hyperplasia | Increase in the number of fibers. |
| Fibrosis | The replacement of muscle fibers by fibrous scar tissue. |
| Sarcolemma | The plasma membrane of a muscle cell. |
| Transverse(T)Tubules | Thousands of tiny invaginations of the sarcolemma. |
| Sarcoplasm | The cytoplasm of a muscle fiber.Includes a substantial amount of glycogen. |
| Myoglobin | Red-colored protein inside the sarcoplasm.This protein found only in muscle,binds oxygen molecules that diffuse into muscle fibers from interstitial fluid. |
| Myofibrils | Contractile organelles of skeletal muscle.(little threads) |
| Sarcoplasmic Reticulum | (SR)A fluid-filled system of membranous sacs encircles each myofibrils. |
| Terminal Cisterns | (reservoirs)Dilated end sas of the sarcoplasmic reticulum. |
| Triad | A transverse tubule and the two terminal cisterns on either side of it. |
| Filaments | Smaller structures within myofibrils |
| Muscular Atrophy | Is a wasting away of muscles.Individual muscle fibers decrease in size because of progressive loss of myofribils. |
| Muscular Hypertrophy | Is an increase in the diameter of muscle fibers due to increased production of myofibrils, mitochondria, sarcoplasmic reticulum,and other organelles. |
| Z Dics | Narrow,plate-shaped regions of dense protein material, seperate one sarcomere from the next. |
| A Band | The darker middle part of the sarcomere, extends the entire length of the thick filaments. |
| I Band | A lighter less dense area that contains the rest of the thin filaments but no thick filaments. |
| H-zone | Narrow in the center of each A band contains thick but no thin filaments. |
| M Line | A region in the center of the H zone that contains proteins that hold the thick filaments together at the center of the sarcomere. |
| Myosin | Functions as a motor protein in all three types of muscle tissue. |
| Actin | Main component in Z discs.Individual molecules join to form an actin filament that is twisted into a helix. |
| Tropomyosin | A regulatory protein that is a component of the thin filament.When a skeletal muscle fiber is relaxed,this covvvers the myosin binding sites on actin molecules thereby preventing myosin from binding to actin. |
| Troponin | A regulatory protein that is a component of thin filament.When calcium ions bind to it,it undergoes a change in shape; this conformational change moves tropomyosin away from myosin binding sites on actin molecules an dmuscle contraction .. |
| Contraction cycle | The repeating sequence of events that causes the filaments to slide. |
| ATP hydrolysis | The myosin head includes an ATP binding site and an ATPase,an enzyme that hydrolyzes ATP into ADP and a phospate group |
| Crossbridges | When they myosin heads attach to actin during contraction. |
| Excitation-Contraction coupling | The steps that connect excistation(a muscle action potential propagating along the sarcolemma and into the T tubules)To contraction(sliding of the filaments) |
| Calsquestrin | Inside the SR,molecules of a calcium-binding protein. |
| Length-Tension Relationship | Indicates how the forcefulness of muscle contraction depends on the length of the sarcomeres within a muscle before contraction begins. |
| Somatic Motor Neurons | The neurons that stimulate skeletal muscle fibers to contract. |
| Neuromuscular Junction(NMJ) | The synapse between a somatic motor neuron and a skeletal muscle fiber. |
| Synapse | A region where communication occurs between two neurons,or between a neuron and a target cell in this case,between a somatic motor neuron and a muscle fiber. |
| Synaptic Cleft | At most synapses a small gap,seperates the two cells. |
| Neurotransmitter | The first cell communicates with the second by releasing a chemical. |
| Synaptic Vesicles | Suspended in the cytosol within each synaptic end bulb are hundreds of membrane-enclosed sacs. |
| Acetylcholine(ACh) | Inside each synaptic vesicle are thousands of molecules,the neurotransmitter released at the NMJ. |
| Acetylcholinesterase(AChe) | This enzyme is attached to collagen fibers in the extracellular matrix of synaptic cleft. |
| Creatine Phosphate | An energy-rich molecule that is found only in muscle fibers. |
| Creatine | A small amino acid like molecule that is syntesized in the liver,kidneys,and pancreas and then trasported to muscle fibers. |
| Anaerobic Cellular Respiration | A series of ATP producing reactions that do not require oxygen. |
| Aerobic cellular respiration | A series of oxygen-requiring reactions that produce ATP in mitochondria. |
| Muscle Fatigue | The inability of a muscle to maintain force of contraction after prolonged activity. |
| Oxygen Debt | Refers to the added oxygen over and above the resting oxygen consumption that is taken into the body after exercise. |
| Recovery Oxygen Uptake | A better term than oxygen debt for the elevated use of oxygen after exercise. |
| Motor Unit | Consists of a somatic motor neuron plus all the skeletal muscle fibers it stimulates. |
| Twitch Contraction | The brief contraction of all the muscle fibers into a motor unit in response to a single action potential in its motor neuron. |
| Myogram | The record of a muscle contraction. |
| Latent Period | The delay which lasts about two milliseconds.Muscle action potential sweeps over the sarcolemma and calcium ions are released from the sarcoplasmic reticulum. |
| Contraction Period | Second phase, last 10-100 msec. During This time Ca2+ binds to troponin,myosin-binding sites on actin are exposed and cross bridges form. |
| Relaxation Period | Third Phase, also lasts 10-100msec, Ca2+ is actively transported back into the sarcoplasmic reticulum myosin binding sites are covered by tropomyosin myosin heads detach from actin and tension in the muscle fiber decreases. |
| Refractory Period | The period of lost excitability, is a characteristic of all muscle and nerve cells. |
| Wave Summation | Phenomenon in which stimuli arriving at different times cause larger contractions. |
| Unfused(Incomplete)Tetanus | When a skeletal muscle fiber is stimulated at a rate of 20-30 times per second,it can only partially relax between stimuli.The result is a sustained but wavering contrations. |
| Fused(complete)Tetanus | When a skeletal muscle fiber is stimulated at a higher rate of 80-100 times per second,it does not relax at all.A sustained contraction in which individual twitches cannot be detected. |
| Motor Unit Recruitment | The Process in which the number of active motor units increases. |
| Muscle Tone | A small amount of tautness or tension in the muscle due to weak,involuntary contractions of its motor units. |
| Flaccid | A stated of limpness in which muscle tone is lost. |
| Isotonic contraction | The tension developed by the muscle remains almost constant while the muscle changes its length. |
| Concentric Isotonic Contraction | If the tension generated is great enough to overcome the resistance of the object to be move the muscle shortens and pulls on another structure such as a tendon to produce movement and to reduce the angle at a joint. |
| Eccentric Isotonic Contraction | When the length of a muscle increases during a contraction. |
| Isometric Contraction | The tension generated is not enough to exceed the resistance of the object to be moved and the muscle does not change its length. |
| Slow Oxidative(SO)fibers | Smallest in diameter and thus are the least powerful type of muscle fibers.They appear dark red because they contain large amounts of myoglobin and many blood capillaries. |
| Fast Oxidative-glycolytie(FOG) fibers | Intermediate in a diameter between the other two types of fibers.Like slow oxidative fibers,they contain large amounts of myoglobin and many blood capillaries. |
| Fast Glicolytic(FG) Fibers | Are largest in diameter and contain the most myofibrils. Hence, they can generate the most powerful contractions. |
| Cardiac Muscle Tissue | The principle tissue in the heart wal. |
| Cardiac Muscle Fibers | The contractile cells of the heart. |
| Smooth Muscle Tissue | Like cardiac muscle tissue,its usually activated involuntarily. |
| Visceral(single-unit)smooth muscle tissue | Of the two types of smooth muscle tissue the most common type.It is found in tubular arrangement that form part of the walls of small arteries and veins and of hollow organs such as the stomach, intestines, uterus,and urinary bladder. |
| Multiunit Smooth Muscle Tissue | The second type of smooth muscle tissue,consist of individual fibers, each with its own motor neuron terminals and with few gap junctions between neighboring fibers. |
| Caveolae | There are small pouchlike invaginations of the plasma membrane. |
| Dense Bodies | In smooth muscle fibers, the thin filaments attach to structures.Functionally similar to z discs in striated muscle fibers . |
| Calmodulin | In one such mechanism, aregulatory protein binds to Ca2+ in the cytosol. |
| Smooth Muscle tone | A state of continued partial contraction. |
| Stress-Relaxation response | Allows smooth muscle to undergo great changes in length while retaining the ability to contract effectively. |
| Mesoderm | As this develops it becomes arranged in dense columns on either side of the developing nervous system. |
| Myotome | First region of somite differentiate: Forms the skeletal muscles of the head, neck, and limbs. |
| Deratome | 2nd region of somite differentiate. Forms the connective tissues including the dermis of the skin |
| Sclerotome | 3rd region of somite differentiate: gives rise to the vertebrae. |
| Mesodermal Cells | Cardiac muscle and Smooth muscle develops from these cells. They migrate to and evelop the developing heart while itis still the form of endocardial heart tubes:they migrate to and evelop the developing gastrointestinal tract and viscera. |
Created by:
caguzman
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