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Micturition Reflex

Is urination a voluntary or involuntary process? Unlike many actions of the digestive system urination is under a combination of voluntary and involuntary control. The parasympathetic nervous provides the initial stimulus for urination. However urination usually cannot proceed with conscious control. It is difficult, if not impossible, to consciously urinate when the bladder is not full enough. In some cases, such as illness or stress urination may proceed involuntarily.

View the animation below, then complete the quiz to test your knowledge of the concept.






1When the urinary bladder becomes stretched, there is an increase in the frequency of action potentials traveling from...
A)the urinary bladder to the sacral region.
B)the parasympathetic neurons from the spinal cord to the urinary bladder.
C)somatic motor neurons.
D)ascending spinal pathways to the pons and cerebrum.
E)neurons in the spinal cord.



2In response to these impulses, which of the following cause the smooth muscle on the urinary bladder to contract?
A)neurons from the urinary bladder to the sacral region
B)the parasympathetic neurons from the spinal cord to the urinary bladder
C)somatic motor neurons
D)ascending spinal pathways to the pons and cerebrum
E)neurons in the spinal cord



3When urination is desired, decreased action potentials along which of the following causes relaxation of the external urinary sphincter?
A)neurons from the urinary bladder to the sacral region
B)the parasympathetic neurons from the spinal cord to the urinary bladder
C)somatic motor neurons
D)ascending spinal pathways to the pons and cerebrum
E)neurons in the spinal cord



4If urination is not convenient, the brain sends impulses down the spinal cord to inhibit the micturition reflex.
A)True
B)False



5The micturition reflex is coordinated by neurons in the spinal cord.
A)True
B)False







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