Valley Quiz - PERIPHERAL NERVOUS SYSTEM Flashcards
Esmolol (Brevibloc) works primarily by competitively antagonizing what adrenergic receptor(s)? a. Alpha l b. Beta 1 C. Beta 2 d. Alpha 1, Beta 1
b. Beta 1
Postsynaptic nicotinic receptors are found at each of the following sites EXCEPT:
a. adrenal medulla.
b. sinoatrial node.
c. autonomic ganglia.
d. skeletal muscle motor end-plate.
B sinoatrial node
The effects of norepinephrine released from sympathetic postganglionic neurons are terminated mainly by
a. metabolism by MAO in the synaptic cleft.
b. metabolism by COMT in the synaptic cleft.
c. diffusion from the synaptic cleft into the blood stream.
d. reuptake by the nerve terminal.
D reuptake by the nerve terminal.
Release of neurotransmitter requires the entry of what substance into the nerve terminal?
a. Sodium
b. Potassium
c. Magnesium
d. Calcium
D Calcium
Which agonist listed below is largely devoid of beta2-adrenergic activity?
a. lsoproterenol
b. Terbutaline
c. Epinephrine
d. Norepinephrine
D Norepinephrine
The effects of ephedrine are due mostly to its
a. stimulation of the nerve terminal to release norepinephrine.
b. direct stimulation of a 1 and a 2 receptors.
c. direct stimulation of B1 and B2 receptors.
d. direct stimulation of a1, B1 and B2 receptors.
A stimulation of the nerve terminal to release norepinephrine.
Low levels of circulating epinephrine cause
a. a reflex decrease in heart rate.
b. a decrease in systolic blood pressure.
c. a decrease in systemic vascular resistance.
d. an increase in diastolic blood pressure.
C a decrease in systemic vascular resistance.
A patient chronically taking propranolol for hypertension is to undergo anesthesia and surgery. His last dose of propranolol was two hours before surgery. During the case, you would be cautious about
administering which of the following drugs?
a. Furosemide
b. Phenylephrine
c. Nitroglycerin
d. Hydralazine
B Phenylephrine
In the patient who is chronically beta-blocked, the beta receptors
a. increase in number.
b. decrease in number.
c. become hypersensitive to beta-adrenergic agonists.
d. become insensitive to beta-adrenergic agonists.
A increase in number. (UP REGULATION)
Alpha-adrenergic receptor blockade produces
a. an increase in systemic vascular resistance.
b. bronchoconstriction.
c. venodilation and a decrease in venous return.
d. an increase in heart rate.
C Venodilation and a decrease in venous return.
You would consider avoiding which of the following adrenergic antagonists in the asthmatic?
a. Labetalol
b. Esmolol
c. Yohimbine
d. Phentolamine
A Labetalol
Which intravenous general anesthetic would you most avoid in the beta-blocked patient?
a. Methohexital
b. Alfentanil
c. Ketamine
d. Propofol
C Ketamine
A farmer who one hour ago was spraying his crops with organophosphate insecticide complains of
abdominal cramps, muscle weakness, and blurred vision. He is wheezing and bradycardic. Treatment
of this condition might reasonably include each of the following agents EXCEPT:
a. physostigmine.
b. atropine.
c. diazepam.
d. pralidoxime.
A physostigmine
Which second messenger promotes bronchoconstriction?
a. Cyclic guanosine monophosphate (cGMP)
b. Inositol triphosphate (IP 3)
c. Cyclic adenosine monophosphate (cAMP)
d. Calmodulin
B inositol triphosphate (IP 3)
Which of the following agents produces the greatest increase in heart rate?
a. Scopolamine
b. Glycopyrrolate
c. Atropine
d. Pilocarpine
C Atropine
Proprioception is carried by
a. A-alpha fibers
b. A-gamma fibers
c. A-delta fibers
d. dC fibers
A A-alpha fibers
Insulin receptors contain an active tyrosine kinase domain. What is the function of a kinase?
a. Kinases exchange GTP for GDP
b. Kinases activate calcium channels on the endoplasmic reticulum
c. Kinases catalyze the addition of a phosphate group to a substrate
d. Kinases degrade cyclic nucleotides (cAMP, cGMP) to inactive products
C Kinases catalyze the addition of a phosphate group to a substrate
The cell bodies (soma) of which of the following structures lie in brainstem and sacral cord areas?
a. postganglionic sympathetic nerves
b. preganglionic sympathetic nerves
c. postganglionic parasympathetic nerves
d. preganglionic parasympathetic nerves
D preganglionic parasympathetic nerves
Which of the following structures is not innervated by the stellate ganglia?
a. bronchioles
b. pupils
c. eyelids
d. nasal vasculature
A bronchioles
The substrate for phoshpolipase C (PLC) is:
a. inositol triphosphate
b. diacylglycerol
c. phosphatidylinositol-4,5-bisphosphate
d. caclium
C
c. phosphatidylinositol-4,5-bisphosphate
The compatibility of general intravenous anesthetics and volatile agents with beta-adrenergic receptor
antagonists. Anesthetics are ranked from those with the least favorable interaction with
beta-blockers to those with the most favorable interaction :
Ketamine Enflurane Halothane Opioids (isoflurane = sevoflurane = desflurane)
Your patient has been treated with an MAO inhibitor for depression. General anesthesia is planned for
a ruptured appendix.
a. What drug will you most avoid using in this patient?
b. What other drug might you also want to avoid using? .
Meperidine (Demerol)
Ephedrine
Your OB patient is given ritodrine for her premature labor.
a. What kind of drug is ritodrine?
b. What are three side-effects of ritodrine?
i. Hyperglycemia or hypoglycemia?
ii. Hyperkalemia or hypokalemia?
iii. Tachycardia or bradycardia?
a. Ritodrine is a tocolytic, meaning it relaxes the pregnant uterus. More specifically, ritodrine is a
beta-2 adrenergic receptor agonist.
b i. hyperglycemia
bii. hypokalemia
biii. tachycardia
Your OB patient becomes hypotensive and needs a vasopressor.
a. What agent may be best in this situation? Ephedrine or phenylephrine
b. Why?
Ephedrine or phenylephrine
Ephedrine does not appreciably decrease uterine blood flow.
The patient will undergo surgery to remove a pheochromocytoma.
a. If you were to both alpha-block and beta-block the patient, would you beta-block the patient before
you alpha-block, or would alpha-block before you beta-block?
b. What alpha-adrenergic blocker could you use to control hypertension during the case?
Block ALPHA receptors first. Alpha-adrenergic receptor blockade causes arterial dilatation, a decrease in systemic vascular resistance, and a decrease in afterload. These changes make it easier for the heart to eject blood after beta-adrenergic receptor blockade. If beta blockade occurred first, heart failure might result because the beta-blocked heart might not be able to eject an adequate stroke volume when systemic vascular resistance and afterload become elevated as a result of increases in circulating epinephrine and norepinephrine.
b. Phentolamine (Regitine) is an alpha blocker that could be selected during the case.
Your patient has severe asthma.
a. What adrenergic agents would you avoid using in this patient?
Avoid drugs that block beta-2 adrenergic receptors such as propranolol or labetalol,
and also avoid drugs that stimulate the release of histamine such as trimethaphan (Arfonad), o-tubocurarine, atracurium, and mivacurium
Your patient is on a high dose beta-blocker.
a. You would avoid using what intravenous general anesthetic? Why?
Ketamine should be avoided.
Ketamine stimulates the sympathetic nervous system, which will constrict blood vessels and increase systemic vascular resistance and afterload. The beta-blocked heart may not tolerate the increased afterload, and heart failure may ensue.
The patient is beta-blocked to treat hypertension. The anesthesiologist terminates the beta-blocker
therapy 48 hours before surgery. Preoperatively, the patient shows tachycardia, hypertension and ECG
signs of myocardial ischemia.
a. What explains the tachycardia and ECG signs of myocardial ischemia?
When beta receptors are blocked by a competitive antagonist, beta receptors up-regulate. When the
beta blocker is withdrawn, the unblocked heart with excessive numbers of beta receptors is hypersensitive to catecholamines. The result is tachycardia, hypertension, and possibly myocardial ischemia.
The patient is beta-blocked to treat hypertension. The anesthesiologist terminates the beta-blocker
therapy 48 hours before surgery. Preoperatively, the patient shows tachycardia, hypertension and ECG
signs of myocardial ischemia.
You probably would treat this problem with what agent?
Esmolol (Brevibloc), because it is short acting and titrating to a desirable blood pressure is fairly easy
to accomplish.
The patient is beta-blocked to treat hypertension. The anesthesiologist terminates the beta-blocker
therapy 48 hours before surgery. Preoperatively, the patient shows tachycardia, hypertension and ECG
signs of myocardial ischemia.
c. Should beta-blocker therapy be discontinued prior to surgery?
No, beta blocker therapy generally should not be discontinued prior to surgery.
- You want to protect the patient from excess salivation.
If you also want to promote sedation, what drug will you use?
If you want to avoid sedation, what drug will you use?
Of the available antisialagogues, which is least efficacious in reducing salivation?
Scopolamine
Glycopyrrolate (robinul)
Atropine
