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NUHS Physiology 1 -

Chpt. 9

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
Created by: oneirishgirl



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