Chapter 14
The Autonomic Nervous System
543
2.
A 32-year-old woman complains of intermittent aching pains in
the medial two fingers of both hands. During such episodes, the
fingers become blanched and then blue. Her history is taken, and
it is noted that she is a heavy smoker. Te physician advises her
that she must stop smoking and states that she will not prescribe
any medication until the patient has discontinued smoking for a
month. What is this patient’s condition, and why was she told to
stop smoking?
3.
±iffany, a 21-year-old college student, is having trouble sleeping,
crying frequently, and having recurrent thoughts of suicide.
An antidepressant is prescribed. Like many such drugs, this
antidepressant has anticholinergic side effects. What side effects
might ±iffany experience in the first week of treatment?
4.
As the aroma of freshly brewed coffee driFed by dozing Henry’s
nose, his mouth started to water and his stomach began to
rumble. Explain his reactions in terms of ANS activity.
16.
What manifestations of decreased autonomic nervous system
efficiency are seen in elderly individuals?
17.
Postganglionic neurons are also called ganglionic neurons. Why
is the latter term more accurate?
Critical Thinking
and Clinical Application
Questions
1.
Mr. Johnson suffers from urinary retention and a hypoactive
urinary bladder. Bethanechol, a drug that mimics acetylcholine’s
autonomic effects, is prescribed to manage his problem. ²irst
explain the rationale for prescribing bethanechol, and then
predict which of the following adverse effects Mr. Johnson might
experience while taking this drug (select all that apply): dizziness,
low blood pressure, deficient tear formation, wheezing, increased
mucus production in bronchi, deficient salivation, diarrhea,
cramping, excessive sweating, undesirable erection of penis.
Related Clinical Terms
Atonic bladder
(ah-ton
9
ik;
a
5
without;
ton
5
tone, tension) A
condition in which the urinary bladder becomes flaccid and
overfills, allowing urine to dribble through the sphincters.
Results from temporary loss of the micturition reflex following
spinal cord injury.
Horner’s syndrome
A condition due to damage to the superior
sympathetic trunk on one side of the body. On the affected side,
the upper eyelid droops (ptosis) and the pupil constricts, and the
person does not sweat on that side of the head.
Vagotomy
(va-got
9
o-me) Cutting or severing the vagus nerve to
decrease secretion of gastric juice. ±reatment for peptic ulcers
that do not respond to medication.
Vasovagal syncope
Vasovagal syncope, also called
neurocardiogenic
syncope
, is the most common cause of fainting. Although it
may be provoked by emotional stress, pain, or dehydration, it
typically occurs during prolonged standing. ²ainting is due to a
drop in blood pressure, which decreases blood flow to the brain.
AT T H E C L I N I C
On arrival at Holyoke Hospital, Jimmy
Chin, a 10-year-old boy, is immobilized
on a rigid stretcher so that he is
unable to move his head or trunk.
The paramedics report that when they found him some 50 feet
from the bus, he was awake and alert, but crying and complaining
that he couldn’t “get up to find his mom” and he had a “wicked
headache.” He has severe bruises on his upper back and head,
and lacerations of his back and scalp. His blood pressure is low,
body temperature is below normal, lower limbs are paralyzed, and
he is insensitive to painful stimuli below the nipples. Although
still alert on arrival, Jimmy soon begins to drift in and out of
unconsciousness.
Jimmy is immediately scheduled for a CT scan, and an operating
room is reserved.
Relative to Jimmy’s condition:
1.
Why were his head and torso immobilized for transport to the
hospital?
2.
What do his worsening neurological signs (drowsiness,
incoherence, etc.) probably indicate? Relate this to the type of
surgery that will be performed.
3.
Assuming that Jimmy’s sensory and motor deficits are due to a
spinal cord injury, at what level do you expect to find a spinal
cord lesion?
4.
Two days after his surgery, Jimmy is alert and his MRI scan
shows no residual brain injury, but pronounced swelling and
damage to the spinal cord at T
4
. On physical examination,
Jimmy shows no reflex activity below the level of the spinal cord
injury. His blood pressure is still low. Why are there no reflexes
in his lower limbs and abdomen?
5.
Over the next few days, his reflexes return in his lower limbs
and become exaggerated. He is incontinent. Why is Jimmy
hyperreflexive and incontinent?
On one occasion, Jimmy complains of a massive headache and
his blood pressure is way above normal. On examination, he is
sweating intensely above the nipples but has cold, clammy skin
below the nipples and his heart rate is very slow.
6.
What is this condition called and what precipitates it?
7.
How does Jimmy’s excessively high blood pressure put him
at risk?
(Answers in Appendix H)
Case Study
Autonomic Nervous System
14
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