TEST
Which43of43the43following43is43a43recognized43function43of43skeletal43muscle?43
1)43A)43guard43body43entrances43and43exits43
B)43maintain43posture
43C)43maintain43body43temperature43
D)43produce43movement43
E)43all43of43the43above43-43answer--E
Nerves43and43blood43vessels43that43service43the43muscle43fibers43are43located43in43the43
connective43tissues43of43the43
A)43myofibrils.43
B)43sarcolemma.43
C)43endomysium.
43D)43sarcomere.43
E)43perimysium.43-43answer--E
Which43of43the43following43best43describes43the43term43sarcoplasmic43reticulum?43
43A)43largely43made43of43myosin43molecules43
B)43storage43and43release43site43for43calcium43ions43
C)43thin43filaments43are43anchored43here43
D)43protein43that43accounts43for43elasticity43of43resting43muscle43
E)43repeating43unit43of43striated43myofibrils43-43answer--B
Interactions43between43actin43and43myosin43filaments43of43the43sarcomere43are43respon
sible43for43
43A)43the43conduction43of43neural43stimulation43to43the43muscle43fiber.43
B)43muscle43fatigue.43
C)43the43striped43appearance43of43skeletal43muscle.43
D)43muscle43contraction.43
E)43muscle43relaxation.43-43answer--D
,The43region43of43the43sarcomere43that43always43contains43thin43filaments43is43the43
43A)43Z43line.43
B)43A43band.43
C)43H43band.43
D)43M43line.43
E)43I43band.43-43answer--E
At43rest,43active43sites43on43the43actin43are43blocked43by43
43A)43calcium43ions.43
B)43troponin43molecules.43
C)43tropomyosin43molecules.43
D)43myosin43molecules.43
E)43ATP43molecules.43-43answer--C
Cross-bridges43are43portions43of43
43A)43actin43molecules.43
B)43myosin43molecules.43
C)43tropomyosin43molecules.43
D)43troponin43molecules.43
E)43calcium43ions.43-43answer--B
When43a43skeletal43muscle43fiber43contracts,43A)43the43zones43of43overlap43get43larger.4
3
B)43the43H43bands43and43I43bands43get43smaller.43
C)43the43Z43lines43get43closer43together.43D)43the43width43of43the43A43band43remains43co
nstant.43
E)43all43of43the43above43-43answer--E
The43following43is43a43list43of43the43events43that43occur43during43a43muscle43contraction.
431.43Myosin43cross-bridges43bind43to43the43actin.
432.43The43free43myosin43head43splits43ATP.43
3.43Calcium43ion43is43released43from43the43sarcoplasmic43reticulum.43
4.43The43myosin43head43pivots43toward43the43center43of43the43sarcomere.43
5.43Calcium43ion43binds43to43troponin.436.43The43myosin43head43binds43an43ATP43molec
ule43and43detaches43from43the43actin.
The43correct43sequence43of43these43events43is43
43A)433,435,431,432,434,436.43
B)431,434,436,432,433,435.43
C)431,433,435,434,436,432.43
D)435,431,434,436,432,433.43
E)433,435,431,434,436,432.43-43answer--E
Active43sites43on43the43actin43become43available43for43binding43after43
43A)43troponin43binds43to43tropomyosin.43B)43calcium43binds43to43tropomyosin.43C)43myo
sin43binds43to43troponin.43
D)43calcium43binds43to43troponin.43
, E)43actin43binds43to43troponin.43-43answer--D
In43an43isotonic43contraction,43
A)43muscle43tension43exceeds43the43load43and43the43muscle43lifts43the43load.43B)43many
43twitches43fuse43into43one.43
C)43tension43rises43and43falls43but43the43muscle43length43is43constant.43
D)43flexion43is43produced.43
E)43the43peak43tension43is43less43than43the43load.43-43answer--A
During43anaerobic43glycolysis43
43A)43oxygen43is43not43consumed.43
B)43pyruvic43acid43is43produced.43
C)43ATP43is43produced.43
D)43all43of43the43above43
E)43B43and43C43only43-43answer--D
The43type43of43muscle43fiber43that43is43most43resistant43to43fatigue43is43the43________43f
iber.43
43A)43intermediate43
B)43fast43
C)43high-density43
D)43anaerobic
43E)43slow43-43answer--E
Shortening43a43muscle43while43it43maintains43constant43tension43is43called43________.43
43A)43complete43tetanus43
B)43an43isometric43contraction43
C)43an43isotonic43contraction43
D)43incomplete43tetanus43
E)43an43isokinetic43contraction43-43answer--C
Which43of43the43following43is43not43a43characteristic43of43a43muscle43cell?43
43A)43Conductivity43
B)43Excitability43
C)43Contractility43
D)43Plasticity43
E)43Extensibility43-43answer--D
The43most43common43lever43systems43in43the43body43are43those43that43have43the43appli
ed43force43between43the43fulcrum43and43the43load.43These43are43called43________43lev
ers.43
A)43fourth-class43
B)43second-class43
C)43fifth-class43
D)43third-class43
E)43first-class43-43answer--D