Chapter 9 nervous system
10. A single motor neuron together with all the muscle fibers it innervates is called a. an end foot. b. a motor unit. c. a dermatome. d. an end plate. e. a myotome.
b. a motor unit.
14. Which energy source has the greatest number of twitches, based on their initial quantities in a typical muscle fiber? a. breakdown of creatine phosphate b. aerobic metabolism c. glycolysis
b. aerobic metabolism
20. Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of a. fatty muscles. b. fast fibers. c. intermediate fibers. d. red muscles. e. slow fibers.
b. fast fibers.
13. The type of contraction in which the muscle fibers do not shorten is called a. treppe. b. isometric. c. isotonic. d. concentric. e. tetany.
b. isometric.
3. What is the result when the zone of overlap is reduced to zero? a. The maximum number of cross-bridges can form. b. The sarcomere cannot shorten further. c. The muscle fiber cannot produce any active tension. d. Optimal resting length occurs
c. The muscle fiber cannot produce any active tension
15. Creatine phosphate a. cannot transfer its phosphate group to ADP. b. is only formed during strenuous exercise. c. acts as an energy reserve in muscle tissue. d. is produced by the process of anaerobic respiration. e. can replace ATP in binding to myosin molecules during contraction
c. acts as an energy reserve in muscle tissue.
2. During which phase of a muscle twitch are active sites on thin filaments exposed, and cross-bridge interactions occur? a. latent phase b. relaxation phase c. contraction phase d. resting phase
c. contraction phase
6. Calcium ions are binding to troponin during the ________ of a muscle twitch. a. contraction phase b. latent period c. latent period and the contraction phase d. recovery phase e. relaxation phase
c. latent period and the contraction phase
19. The type of muscle fiber that is most resistant to fatigue is the ________ fiber. a. intermediate b. anaerobic c. slow d. fast e. high-density
c. slow
skeletal muscles contract 2
muscle cell use energy (ATP) - shorten and generate tension through interactions betweem thick (myosin) & thin (acting) filaments
skeletal muscle contract
skeletal muscle contract -pulls on attached tendon - creates tension (requires energy) - tension applied to object pulls object towards source of tension - must overcome resistance
sliding filament theory
then finments arsliding toward the center of each sarcomere, alongside the thick filaments
motor unit
A motor neuron and all of the muscle fibers it innervates.
excitation- contraction coupling
-Ca ++ released from cisternae of sarcoplasmic reticulum -Ca++ trigger interactions between actin and myosin - muscle fibers contract & ATP is used - filament interactions produce actice tension
3 pathways in which ATP is regenerated
1. coupled reaction with Creatine Phoshate (CP) 2. anaerobic cellar respiration = 2 ATP 3.aerobic caellular respiration = 36 ATP
when a skeleton muscle contraction
1. the H zones and I bands get smaller 2. zones of overlap get larger 3. Z lines move closer together 4. the width of A band remains constant
17. After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs. a. an oxygen debt b. tetanus c. paralysis d. atrophy e. treppe
a. an oxygen debt
During which type of contraction does the rate of elongation depend on the difference between the tension developed by the active muscle fibers and the size of the load? a. eccentric contraction b. isometric contraction c. concentric contraction d. incomplete tetanus
a. eccentric contraction
11. The increase in muscle tension that is produced by increasing the number of active motor units is called a. recruitment. b. wave summation. c. treppe. d. complete tetanus. e. incomplete tetanus
a. recruitment.
9. If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called a. wave summation. b. recruitment. c. incomplete tetanus. d. complete tetanus. e. treppe.
a. wave summation
myofibrils shorten
causing the muscle fiber to shorten
neurotransmitter
chemical substance released from motor end fiber, cuses stimulation of the sarcolemma of muscle fiber
4. Which of the following occurs during the relaxation phase of a muscle twitch? a. Tension rises. b. Active sites are being exposed. c. The number of cross-bridges is constant. d. Calcium levels are falling.
d. Calcium levels are falling.
18. During the recovery period the body's need for oxygen is increased because a. the liver requires more oxygen to produce lactic acid. b. the individual is panting. c. muscle cells are producing energy anaerobically. d. additional oxygen is required to restore energy reserves consumed during exercise. e. the muscles are not producing ATP.
d. additional oxygen is required to restore energy reserves consumed during exercise
16. During anaerobic glycolysis a. ATP is produced. b. oxygen is not consumed. c. pyruvic acid is produced. d. all of the above e. none of the above
d. all of the above
7. The smooth but steady increase in muscular tension that is produced by increasing the number of active motor units is called: a. treppe. b. wave summation. c. complete tetanus. d. recruitment.
d. recruitment.
5. The rapid rise and fall in force produced by a muscle fiber after a single action potential is a. a muscle action potential. b. an unfused tetanus. c. an end plate potential. d. a tetanus. e. a twitch.
e. a twitch
8. When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension, and a higher stimulation frequency eliminates the relaxation phase. This is called a. a twitch. b. wave summation. c. recruitment. d. incomplete tetanus. e. complete tetanus.
e. complete tetanus.
neuromusclar junction
synapes between a motor neuron and a skeletal muscle fiber
achetylcholine (ach)
the neurotransmitter in motor neurons to skeletal muscle
motor end plate
the specific part of a skeletal muscle fiber's sarcolemma directly beneath the NMJ