A motor unit refers to
a. a single motor neuron plus all of the muscle fibers it innervates.
b. a single muscle fiber plus all of the motor neurons that innervate it.
c. all of the motor neurons supplying a single muscle.
d. a pair of antagonistic muscles.
e. a sheet of smooth muscle cells connected by gap junctions.
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Question 2) Which statement regarding control of digestive processes is incorrect?
a. short reflexes influence motility and secretion in localized areas.
b. all elements of the short reflexes are contained within the digestive organ's wall.
c. hormones play a role.
d. osmoreceptors monitor the acidity of the luminal contents.
e. there are stretch receptors in the walls of digestive organs.
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Question 3) Which of the following is involved in the gradation of muscle contraction?
a. variation in the number of motor units activated
b. variation in the frequency of action potentials initiated in each muscle fiber
c. variation in the size of the action potentials initiated in each muscle fiber
d. both (a) and (b) above.
e. all of these answers.
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Question 4) The wall of the digestive tract contains different types of sensory receptors that:
a. respond to chemical changes
b. respond to mechanical changes
c. respond to temperature changes
d. both (a) and (b)
e. both (a) and (c)
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Question 5) Which of the following is not a method of gradation of skeletal muscle contraction?
a. twitch summation
b. motor unit recruitment
c. stimulating variable portions of each motor unit
d. varying the number of motor units stimulated
e. varying the frequency at which a motor unit is stimulated
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Question 6) 9,500 ml of fluid is absorbed from the digestive tract daily. The ultimate source of most of this fluid is
a. food and fluid ingested during meals.
b. stored within secretory cells of the digestive tract.
c. the plasma.
d. the accessory digestive organs.
e. metabolic water.
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Question 7) Which of the following results in muscle relaxation?
a. addition of magnesium to muscle cells.
b. AChE activity.
c. return of calcium to lateral sacs.
d. sliding together of thick and thin filaments.
e. two of these answers.
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Question 8) The enteric nervous system
a. includes the myenteric plexus.
b. includes the submucosal plexus.
c. includes vagal nerve efferents.
d. both (a) and (b) above.
e. both (a) and (c) above.
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Question 9) Which of the following is not a determinant of whole muscle tension?
a. the number of muscle fibers contracting.
b. the tension produced by each contracting fiber.
c. the extent of motor-unit recruitment.
d. the frequency of stimulation.
e. the proportion of each motor unit that is contracting at any given time.
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Question 10) Carbohydrates are absorbed as
a. polysaccharides.
b. disaccharides.
c. monosaccharides.
d. amino acids.
e. fatty acids.
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