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Muscle Hist/Phys.
Ch. 9 Muscle Histology & Physiology TEST Review
| Question | Answer |
|---|---|
| The statement...Most skeletal muscles are attached to bones, are typically under conscious control... Describes which major function of muscles? | Body Movement |
| The statement... Skeletal muscles constantly maintain tone...Describes which major function of muscles? | Maintenance of Posture |
| The statement... Contraction of cardiac muscle causes heart to contract...Describes which major function of muscles? | Heart Beat |
| The statement... When skeletal muscles contract, the increase in metabolism creates a by-product which our body needs for homeostasis...Describes which major function of muscles? | Production of Heat |
| The statement... Smooth muscles within the walls of internal organs and vessels causes constriction of these structures...Describes which major function of muscles? | Organ/Vessel Constriction |
| The statement... Skeletal muscles are involved in all aspects of speaking, writing, typing, gesturing and facial expressions...Describes which major function of muscles? | Communication |
| The ability of muscle to shorten with a force | Contractility |
| The capacity of muscle to respond to a stimulus | Excitability |
| Muscle can be stretched to its normal resting length and beyond to a limited degree | Extensibility |
| Ability of muscle to recoil to its original resting length after it has been stretched | Elasticity |
| Attached to bones, long and cylindrical in form, multi-neucleated and striated | Skeletal Muscle |
| Spindle shaped, single centrally located nucleus and works to move food and fluids throughout the body | Smooth Muscle |
| Cylindrical and branched in form, single centrally located nuclei and functions to pump blood throughout the body | Cardiac Muscle |
| Connective tissue sheath that surrounds a muscle fasciculus | Perimysium |
| Less mature multinucleated cells called ___ give rise to muscle fibers | Myoblasts |
| The number of skeletal muscle fibers remains relatively ___ after birth | Constant |
| Alternating light and dark bands give skeletal muscle a ___ appearance | Striated |
| Surround each muscle fiber and is composed primarily of reticular fibers | External lamina |
| Plasma membrane of the muscle fiber | Sarcolemma |
| Delicate network of loos connective tissue with numerous reticular fibers which surrounds each muscle fiber outside the external lamina | Endomysium |
| Each bundle ensheathed by perimysium | Fasciculus |
| Composed of dense collagenous connective tissue and covers the entire surface of the muscle | Epimysium |
| Connective tissue that covers the body by forming a sheet of tissue under the skin | Fascia |
| Specialized nerve cells | Motor neurons |
| Cytoplasm without myofibrils | Sarcoplasm |
| Threadlike structure approximately 1-3 micrometers in diameter | Myofibril |
| Protein filaments | Myofilaments |
| Thin myofilaments | Actin |
| Thick myofilaments | Myosin |
| Actin and myosin myofilaments are organized in highly ordered units | Sarcomeres |
| Two strands coiled like a double helix composing the main structure of actin myofilaments | Fibrous Actin |
| Each F actin is composed of | Globular Actin |
| G actin each have an ___ to which complexes attach during contraction | Active sites |
| Myosin molecules are shaped like ___ | Golf clubs |
| When actin and myosin bind they are referred to as | Cross-bridges |
| Filamentous network of protein forming a disklike structure for the attachment of actin myofilaments | Z disk |
| Extends length of myosin myofilament within a sarcomere | A band |
| Where actin and myosin myofilaments do NOT overlap and only myosin is present | H zone |
| Includes all events that result in actin myofilaments sliding over myosin myofilaments to shorten the sarcomeres of muscle fibers | Sliding filament model |
| Transmitted along the axons to muscle fibers | Action potentials |
| Means there is a voltage difference across the muscle fiber membrane | Polarized |
| Resting membrane potential is measured in | Millivolts |
| Molecule that binds to a receptor | Ligand |
| Protein or glycoprotein that has a receptor site to which a ligand can bind | Receptor |
| Channels which open in response to a ligand binding | Ligand-gated channel |
| Channels which open in response to a voltage change | Voltage-gated channel |
| Occurs when the inside of the plasma membrane becomes less negative | Depolarization |
| Occurs when the membrane potential returns to it's resting value | Repolarization |
| Action potentials occur according to the | All or None Principle |
| To spread across the plasma membrane | Propagate |
| Number of action potentials produced per unit of time | Action Potential Frequency |
| Consists of the axon terminals and the area of muscle fiber sarcolemma they innervate | Neuromuscular Junction |
| Space between the axon terminal and the muscle fiber | Synaptic Cleft |
| Organic molecule composed of acetic acid and choline which functions as a neurotransmitter | Acetylcholine |
| Substance released from presynaptic membrane that diffuses across the cleft and stimulates or inhibits production of an action potential | Neurotransmitter |
| Keeps ACh from accumulating within the synaptic cleft | Acetylcholinesterase |
| Mechanism by which an action potential causes contraction of a muscle fiber | Excitation-Contraction Coupling |
| Highly specialized smooth ER found in skeletal muscle fibers | Sarcoplasmic Reticulum |
| A T tubule and the two adjacent terminal cisternae together form a ___ | Triad |
| Muscles contract and cannot relax and is followed by fatigue of the muscles | Spastic Paralysis |
| Muscle is incapable of contracting in response to nervous stimulation | Flaccid Paralysis |
| Results from the production of antibodies that bind to ACh receptors, eventually causing the destruction of the receptor and thus reducing the number of receptors | Myasthenia Gravis |
| Movement of the myosin molecule while the cross-bridge is attached | Power Stroke |
| Return of the myosin head to its original position after cross-bridge release | Recovery Stroke |
| Relaxation occurs as a result of the ___ of calcium ions back into sarcoplasmic reticulum | Active Transport |
| Contraction of a muscle in response to a stimulus that causes an action potential in one or more muscle fibers | Muscle Twitch |
| The time between application of the stimulus to the motor neuron and the beginning of contraction | Lag Phase |
| Does not produce an action potential and no muscle contraction occurs | Subthreshold Stimulus |
| Strength of contractions can range from weak to strong depending on the strength of the stimuli | Graded Fashion |
| Force of contraction increases as more and more motor units are stimulated | Multiple Motor Unit Summation |
| Muscle fibers partially relax between the contractions | Incomplete Tetanus |
| Potentials are produced so rapidly in muscle fibers that no muscle relaxation occurs between them | Complete Tetanus |
| Tension produced by a muscle increases as the frequency of contractions increases | Multiple-Wave Summation |
| Graded response which occurs in muscle that has rested for a prolonged period of time | Treppe |
| Length of muscle doesn't change, but the amount of tension increases during contraction | Isometric Contractions |
| Amount of tension produced by muscle is constant during contraction bu the length of the muscle changes | Isotonic Contractions |
| Isotonic contractions in which tension is great enough to overcome opposing resistance | Concentric Contractions |
| Isotonic contractions in which tension is maintained by opposing resistance is great enough to increase length | Eccentric Contractions |
| Constant tension produced by muscles of the body for long periods of time | Muscle Tone |
| Muscle length plotted against the tension produced by the muscle in response to maximal stimuli | Active Tension Curve |
| Decreased capacity to do work and reduced efficiency of performance that normally follows a period of activity | Fatigue |
| Most common type of fatigue | Psychologic Fatigue |
| Muscles are capable of functioning but the individual "perceives" the inability to go on | Psychologic Fatigue |
| Results from ATP depletion | Muscular Fatigue |
| Least common type of fatigue | Synaptic Fatigue |
| Muscle soreness and pain, felt after extreme activity, is often the result of ___ resulting from damage to muscle fibers and the connective tissue | Inflammation |
| Weight lifters and those who lift heavy objects usually assume positions so that their muscles are stretched close to their ___ before lifting | Optimum Length |
| Development of rigid muscles hours after death | Rigor Mortis |
| Muscles become incapable of either contracting OR relaxing as a result of extreme muscular fatigue | Physiologic Contracture |
| During resting conditions, energy from aerobic respiration is used to synthesize ___ | Creatine Phosphate |
| Requires oxygen and releases ATP, water and carbon dioxide as by-products | Aerobic respiration |
| Dos not require oxygen and releases ATP and lactic acid | Anaerobic respiration |
| Oxygen take in by the body, above the required for resting metabolism after exercise | Oxygen debt |
| Contract slowly, smaller in diameter and fatigue resistant | Slow-twitch Muscle Fibers |
| Contract quickly, intermediate/large in diameter and most are quick to fatigue | Fast-twitch Muscle Fibers |
| Dark pigment which binds oxygen and acts as a reservoir for it when blood does not supply an adequate amount | Myoglobin |
| Synthetic hormones which increase size and strength of muscles | Anabolic Steroids |
| May be used inappropriately to increase muscle size and may produce adverse health affects when used often and in large doses | Human Growth Hormone |
| Distributed widely throughout the body and variable in function | Smooth Muscle |
| Involves rapid skeletal muscle contractions that produce shaking rater than coordinated movements | Shivering |
| Muscles increase in size | Hypertrophy |
| Muscles decrease in size | Atrophy |
| Actin filaments are attached to ___ scattered through the cell cytoplasm of smooth muscle | Dense Bodies |
| Shallow invaginated areas along the surface of the plasma membrane of smooth muscle | Caveolae |
| Enzyme which removes the phosphate group from the myosin molecules | Myosin phosphatase |
| Occurs in sheets or single cells and can function as large or small units | Multiunit Smooth Muscle |
| Occurs in sheets and includes smooth muscle of digestive tract | Visceral Smooth Muscle |
| Group of cells which tend to develop action potentials more rapidly than other cells | Pacemaker Cells |
| Found only in the heart | Cardiac Muscle |
| Cell to cell attachments found in cardiac muscle tissue | Intercalated Disks |
| During depolarization, permeability of the plasma membrane to sodium ___ | Increases |
| During repolarization, permeability of the plasma membrane to potassium ___ | Increases |
| With a stimuli of increasing strength, ___ is capable of a graded response | Whole muscle |
| During the lag phase of muscle contraction ___ binds to troponin | Calcium |
| Myosin myofilaments are attached to delicate protein filaments that form the ___ | M line |
| Inflammation of fibrous connective tissue, resulting in stiffness, pain and soreness | Fibrositis |
| Muscle atrophy that results from lack of muscle use | Disuse atrophy |
| One of the largest known proteins | Titin |
| Results when nerves that supply skeletal muscles are severed | Denervation Atrophy |
| Painful, spastic contractions of muscles | Cramps |
| You would expect to see numerous ___ within the leg muscles cells of a world-class marathon runner due to the need of massive amounts of ATP | Mitochondria |
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SavannahElkins
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