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61 Cards in this Set
- Front
- Back
Which muscle(s) can contract without the need for nervous stimulation?
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smooth and cardiac muscle
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The term for shortening of a muscle while maintaining constant tension is
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isotonic contraction
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Release of ACh
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increases permeability of the sarcolemma
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Which of the following best describes the resting membrane potential (RMP)?
A) The extracellular environment is negatively charged B)The intracellular environment is negatively charged C)It has a voltage of about +75 mV D)It depends on the muscle fiber absorbing potassium ions from the ECF E)The intracellular environment has more positively charged sodium |
B) The intracellular environment is negatively charged
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What is the purpose of the triad?
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The triad allows for Ca2+ release when a muscle fiber is excited
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Which of the following individuals would have more mitochondria in his skeletal muscle?
A)a 22-year-old football player B)a newborn C)a model on a reduced-calorie diet D)a long-term hospice patient E)a 50-year-old sedentary computer programmer |
A)a 22-year-old football player
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Loss of muscle mass from lack of activity is termed
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atrophy
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Which of the following is very important for muscle to continue contraction during anaerobic respiration?
A)protease B)acid phosphatase C)cholinesterase inhibitors D)myokinase E)acetylcholinesterase |
D) myokinase
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Which of the following has the largest mitochondria?
A)cardiac muscle B)slow oxidative fibers C)fast glycolytic fibers D)intermediate fibers E)smooth muscle |
A)cardiac muscle
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The triads of a muscle fiber consist of what?
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two terminal cisternae and one T tubule.
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Collagen is...
A)impermeable B)expendable C)elastic D)contractile E)excitable |
C)elastic
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A volleyball player depends on the gastrocnemius muscles for plantar flexion, whereas a marathon runner depends more on the soleus muscles for the same action. This is because the soleus muscles
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make more use of aerobic respiration.
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In skeletal muscle, alternating light and dark bands are termed
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striations
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Which of the following is not a purpose of the excess postexercise oxygen consumption in muscle?
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To neutralize carbon dioxide buildup
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Duing muscle contraction, a single myosin head consumes ATP at a rate of about
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9ATP per second
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The minimum stimulus needed to cause muscle contraction is called
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The threshold
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To stimulate muscle contraction, acetylcholine is released from the ___
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Synaptic knob
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. As you are lifting a box someone places extra weight on top of it. For your muscle to continue contracting and lifting the box, the muscle must
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Recruit more muscle fibers.
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protein that acts as a calcium receptor in skeletal muscle is
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troponin
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A skeletal muscle generates the greatest tension when it is
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In a state of treppe
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Which of the following is not a purpose of the excess postexercise oxygen consumption in muscle?
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to neutralize carbon dioxide buildup
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Which muscle type depends solely on the sarcoplasmic reticulum as its calcium source?
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skeletal muscle
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Aerobic respiration produces approximately _____ more ATPs per glucose molecule than glycolysis does.
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36
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Creatine kinase
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catalyzes the transfer of phosphate from CP to ADP.
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A myofilament that flanks a thick filament and anchors it to a Z disc is called
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an elastic filament.
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Athletes who train at high altitudes increase their red blood cell count and thus increase their oxygen supply during exercise. Increased oxygen supply results in
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longer aerobic respiration.
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Drugs called calcium channel blockers may be used to lower blood pressure by causing arteries to vasodilate. These drugs
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prevent calcium from entering smooth muscle, thus allowing the muscle to relax
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The sarcolemma of a resting muscle fiber is most permeable to
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potassium
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Which of the following is not a characteristic of a muscle cell?
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plasticity
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The training regimen of a competitive weight lifter is designed partly to
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increase the average number of myofibrils per muscle fiber.
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The contraction strength of smooth muscle is relatively independent of its resting length partly because
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it does not have Z discs.
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The purpose of varicosities in muscle physiology is
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to release norepinephrine.
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Helps maintain blood pressure
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Smooth muscle
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Squeezes or propels substances (i.e., food, feces) through organs
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Smooth muscle
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skeletal muscle
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cell: very long and cylindrical, extends length of muscle fasciculi
nucleus: multiple, peripherally located striated, voluntary, incapable of spontaneous contraction |
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smooth muscle
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cell: spindle shaped
nucleus: single centrally located nonstriated, involuntary, sometimes capable of spontaneous contraction |
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cardiac muscle
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cell: cylindrical and branched
nucleus: single centrally located striated, involuntary, capable of spontaneous contractions |
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Epimysium
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an overcoat of dense collagenous connective tissue that surrounds the entire muscle
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Perimysium
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fibrous connective tissue that surrounds fascicles
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Endomysium
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fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber
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Actin
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(thin) myofilaments consist of two helical polymer strands of F actin (composed of G actin), tropomyosin, and troponin
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G actin
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contains the active sites to which myosin heads attach during contraction
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regulatory subunits bound to actin
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Tropomyosin and troponin
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Myosin molecules
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-A head with an ATPase, which breaks down ATP
-A hinge region, which enables the head to move -A rod |
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cross-bridge
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formed when a myosin head binds to the active site on G actin
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the smallest contractile unit of a muscle
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sacromere
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Z disks
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a coin-shaped sheet of proteins (connectins) that anchors the thin filaments and connects myofibrils to one another
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how many actin myofilaments surround a myosin myofilament?
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6
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M lines
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appear darker due to the presence of the protein desmin
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The nervous system stimulates muscles to contract through electric signals called
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action potentials
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in a resting cell, the charge on the inside of the plasma membrane is
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negative
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action potential
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a reversal of the resting membrane potential so that the inside of the plasma membrane becomes positive
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Contains ACh receptors
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Motor end plate of a muscle
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Contain the neurotransmitter acetylcholine (ACh)
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Axonal endings
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The enzyme acetylcholinesterase removes acetylcholine from the synaptic cleft by
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breaking it down into acetic acid and choline
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Sarcoplasmic reticulum (SR)
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an elaborate, smooth endoplasmic reticulum that mostly runs longitudinal and surrounds each myofibril
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Functions in the regulation of intracellular calcium levels
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Sarcoplasmic reticulum
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The contraction of a muscle as a result of one or more muscle fibers contracting
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muscle twitch
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Has lag, contraction, and relaxation phases
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muscle twitch
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Stimulus of increasing frequency increase the force of contraction
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multiple-wave summation
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stimuli of increasing strength result in graded contractions of increased force as more motor units are recruited
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multiple motor unit summation
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