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NUHS Physiology 1 -
Chpt. 9
Question | Answer |
---|---|
Striated muscle attached to bone or skin and responsible for skeletal movements and facial expression; controlled by somatic nervous system (Has multiple nuclei and is peripherally located) | Skeletal muscle |
Heart muscle (Has one nucleus and is centrally located) | Cardiac muscle |
Muscle having transverse banding pattern due to repeating sarcomere structure (Cardiac Muscle & Skeletal Muscle) | Striated muscle |
Non-striated muscle that surrounds hollow organs and tubes (Has one nucleus and is centrally located) | Smooth muscle |
Muscle cell | Muscle fiber |
Embryological cell that gives rise to muscle fibers | Myoblasts |
Undifferentiated cell found within skeletal muscle tissue that can fuse and develop into new muscle fiber following muscle injury | Satellite cells |
Enlargement of a tissue or organ due to increased cell size rather than increased cell number | Hypertrophy |
Number of muscle fibers bound together by connective tissue | Muscle |
Collagen fiber bundle that connects skeletal muscle to bone and transmits muscle contraction force to the bone | Tendons |
Specialized cell containing actin and myosin filaments and capable of generating force and movement | Muscle cell |
Bundle of thick and thin contractile filaments in cytoplasm of striated muscle; myofibrils exhibit a repeating sarcomere pattern along longitudinal axis of muscle | Myofibrils |
Repeating structural unit of myofibril; composed of thick and thin filaments; extends between two adjacent Z lines | Sarcomere |
Myosin filament in muscle cell | Thick filaments |
Contractile protein that forms thick filaments in muscle fiber | Myosin |
Actin filament in muscle cell | Thin filaments |
Regulatory protein bound to actin and tropomyosin af striated muscle thin filaments; site of calcium binding that initiates contractile activity | Troponin |
Regulatory protein capable of reversibly converting binding sites on actin; associated with muscle thin filaments | Tropomyosin |
One of the transverse bands making up repeated striations of cardiac and skeletal muscle; region of aligned myosin-containing thick filaments | A band |
Structure running across myofibril at each end of striated muscle sarcomere; anchors one end of thin filaments and titn | Z line |
One of transverse bands making up repeating striations of cardiac and skeletal muscle; located between A bands of adjacent sarcomeres and bisected Z line | I band |
One of transverse bands making up striated pattern of cardiac and skeletal muscle; light region that bisects A band | H zone |
Transverse stripe occurring at the center of the A band in cardiac and skeletal muscle; location of energy-generating enzymes and proteins connecting adjacent thick filaments | M line |
Protein that extends from the Z line to the thick filaments and M line of skeletal muscle sarcomere | Titin |
A protein that, with myosin, constitutes the contractile apparatus of muscle cells; it also is part of the cytoskeleton found in all cells | Actin |
In muscle, myosin projection extending from thick filament and capable of exerting force on thin filament, causing the filaments to slide past each other | Cross-bridges |
Operation of the force-generating process in a muscle | Contractions |
Return of a muscle to a low force-generating state, caused by detachment of cross-bridge | Relaxation |
Process of muscle contraction in which shortening occurs by thick and thin filaments sliding past each other | Sliding-filament mechanism |
Pair of large, coiled polypeptides that makes up the rod and globular head of a myosin molecule | Heavy chains |
Pair of small polypeptides bound to each globular head of a myosin molecule; function is to modulate contraction | Light chains |
Sequence of events between binding of a cross-bridge to actin, its release, and reattachment during muscle contraction | Cross-bridge cycle |
Stiffness of skeletal muscles after death due to failure of cross-bridges to dissociate from actin because of the loss of ATP | Rigor mortis |
In muscle fibers, mechanism linking plasma membrane stimulation with cross-bridge force generation | Excitation-concentration coupling |
Endoplasmic reticulum in muscle fier; site of storage and release of calcium ions | Sarcoplasmic reticulum |
Enlarged region at end of each sarcoplasmic reticulum segment; adjacent to transverse tubule | Lateral sacs |
Tubule extending from striated-muscle plasma membrane into the fiber, passing between opposed sarcoplasmic reticulum segments; conducts muscle action potential into muscle fiber | Transverse tubule (T-tubule) |
Large extension of sarcoplasmic reticulum calcium channels (ryanodine receptors), which connect them to the T-tubule membrane and mediate excitation-contraction coupling in skeletal muscle | Junctional feet (foot processes) |
Non-conducting calcium channels in the T-tublule membranes of skeletal muscle cells, which act as voltage sensors in excitation-contraction coupling | Dihydropyridine (DHP) receptor |
Calcium-release channel found in the lateral sacs of the sarcoplasmic reticulum in skeletal muscle cells | Ryanodine receptor |
Somatic efferent neuron, which innervates skeletal muscle | Motor neurons |
Motor neuron plus the muscle fibers it innervates | Motor unit |
A neurotransmitter released by pre- and postganglionic parasympathetic neurons, preganglionic sympathetic neurons, somatic neurons, and some CNS neurons | Acetylcholine (ACh) |
Specialized region of muscle cell plasma membrane that lies directly under axon terminal of a motor neuron | Motor end plate |
Synapselike junction between an axon terminal of an efferent nerve fiber and a skeletal muscle fiber | Neuromuscular junction |
Depolarization of motor end plate of skeletal muscle fiber in response to acetylcholine; initiates action potential in muscle plasma membrane | End-plate potential (EPP) |
Hydrolysis of ATP by myosin energizes the cross-bridges, providing the energy for force generation | Step 1: Function of ATP in Skeletal Muscle Contraction |
Binding of ATP to myosin dissociates cross-bridges bound to actin, allowing the bridges to repeat their cycle of activity | Step 2: Function of ATP in Skeletal Muscle Contraction |
Hydrolysis of ATP by the CA2+-ATPase in the sarcoplasmic reticulum provides the energy for the active transport of calcium ions into the reticulum, lowering cytosolic calcium to prerelease levels, ending the contraction | Step 3: Function of ATP in Skeletal Muscle Contraction |
Enzyme that breaks down acetylcholine into acetic acid and choline | Acetylcholinesterase |
Deadly South American arrowhead poison that binds strongly to nicotinic ACh receptors, not allowing ACh to bind, resulting in no EPP in the motor end plate and no contraction | Curare |
The muscarinic receptor antagonist antidote for nerve gas | Atropine |
Potent toxin that blocks the release of acetylcholine from nerve terminals | Botulism |
The force exerted on an object by a contracting muscle | Tension |
The force exerted on the muscle by an object (usually its weight) | Load |
Contraction of muscle under condition in which it develops tension but does not change length | Isometric |
Containing the same number of effectively nonpenetrating solute particles as normal extracellular fluid | Isotonic |
Muscle activity that involves shortening of muscle length | Concentric contraction |
Muscle activity that is accompanied by lengthening of the muscle generally by an external load that exceeds muscle force | Eccentric contraction (lengthening) |
Mechanical response of muscle to single action potential | Twitch |
Period lasting several milliseconds between action potential initiation in a muscle fiber and beginning of mechanical activity | Latent period |
Time between beginning of force development and peak twitch tension by the muscle | Contraction time |
Increase in muscle tension or shortening in response to rapid, repetitive stimulation relative to single twitch | Summation |
Maintained mechanical response of muscle to high-frequency stimulation (Lock Jaw) | Tetanus |
Stimulation of skeletal muscle at a low-to-moderate action potential frequency that results in oscillating, submaximal force | Unfused tetanus |
Skeletal muscle activation in which action potential frequency is sufficiently high to cause a smooth, sustained, maximal strength contraction | Fused tetanus |
Sarcomere length at which muscle fiber develops maximal isometric tension | Optimal length L0 |
Molecule that transfers phosphate and energy to ADP to generate ATP | Creatine phosphate |
Decrease in muscle tension with prolong activity | Muscle fatigue |
Build up of potassium ions in the small volume of the T-tubules during the repolarization of repetitive action potentials. Elevated external potassium concentration leads to a persistent depolarization of the membrane potential | Conduction failure |
Elevated hydrogen ion concentration alters protein conformation and activity. | Lactic Acid build-up |
Muscle fatigue due to failure of appropriate regions of cerebral cortex to excite motor neurons | Central command fatigue |
Type of skeletal muscle fiber that has high intrinsic contraction speed and abundant capacity for production of ATP by aerobic oxidative phosphorylation | Fast twitch fibers (Type 2b) |
Type of skeletal muscle fiber that has slow intrinsic contraction speed but fatigues very slowly due to abundant capacity for production of ATP by aerobic oxidative phosphorylation | Slow twitch fibers (Type 1) |
Muscle fiber that has numerous mitochondria and therefore a high capacity for oxidative phosphorylation | Oxidative fibers |
Muscle fiber protein that binds oxygen | Myoglobin |
Muscle fiber having high oxidative capacity and large amount of myoglobin | Red muscle fibers |
Skeletal muscle fiber that has a high concentration of glycolytic enzymes and large glycogen stores | Glycolytic fibers |
Muscle fiber lacking appreciable amounts of myoglobin | White muscle fibers |
Activation of additional cells in response to increased stimulus strength; increasing the number of active motor units in a muscle | Recruitment |
Bending a joint | Flexion |
Straightening a joint | Extension |
Muscle whose action opposes intended movement | Antagonist |
Cytoplasmic structure to which thin filaments of a smooth muscle fiber are anchored | Dense bodies |
Smooth-muscle protein kinase; when activated by Ca-calmodulin, phophorylates myosin light chain | Myosin light-chain kinase |
Enzyme that removes high-energy phosphate from myosin; important in the relaxation of smooth muscle cells | Myosin light-chain phosphatase |
Contractile state of some smooth muscles in which force can be maintained fro prolonged periods with very little energy use; cross-bridge cycling slows to the point where thick and thin filaments are effectively "latched" together | Latch state |
Smooth-muscle tension due to low-level cross-bridge actvity in absence of external stimuli | Smooth muscle tone |
Spontaneous gradual depolarization to threshold of some nerve and muscle cells' plasm membrane | Pacemaker potential |
Slow, rhythmic oscillation of smooth-muscle membrane potentials toward and away from threshold, due to regular fluctuations in ionic permeability | Slow waves |
Swollen region of axon; contains neurotransmitter-filled vesicles; analogous to presynaptic ending | Varicosities |
Smooth muscle that responds to stimulation as single unit because gap junctions join muscle fibers, allowing electrical activity to pass from cell to cell | Single unit smooth muscles |
Smooth muscle that exhibits little, if any, propagation of electrical activity from fiber to fiber and whose contractile activity is closely coupled to its neural input | Multi unit smooth muscles |
Structure connecting adjacent cardiac myocytes, having components for tensile strength and low-resistance electrical pathways (gap junctions) | Intercalated disks |
Voltage-gated channel permitting calcium entry into heart cells during the action potential; L denotes the long-lasting open time that characterizes these channels | L-type calcium channels |
Increase in muscle fiber size | Hypertrophy |
Decrease in muscle fiber size | Atrophy |
Functioning unit structure in contraction | Myofibril function |
Binds to Troponin which pulls Tropomyosin off of the cross-bridge binding sites allowing for myosin to activate | Calcium |
Toxin/gas that inhibits acetylchoinesterase | Serin gas |