Chapter 46: Physiology of the Autonomic and Central Nervous Systems and Indications for the Use of Drug Therapy

The nurse administers epinephrine intravenously to a client diagnosed with heart block. In what order would the nurse predict the steps of signal transduction and intracellular events that occur when the beta-adrenergic receptors are stimulated? Drag the statements into the proper order. A. Epinephrine binds to the beta receptor and initiates intercellular activity. B. Epinephrine-beta receptor complex activates G protein, which reacts with guanosine triphosphate. C. Activated G protein activates the enzyme adenyl cyclase. D. Increases in cyclic adenosine monophosphate (cAMP) occur. E. Cyclic adenosine monophosphate (cAMP) initiates intracellular activities, including an increase in atrioventricular conduction.

ANS: A, B, C, D, E Rationale: First, epinephrine, the first messenger, binds to the beta receptor and initiates intercellular activity. Next, the epinephrine-beta receptor complex activates G protein, which reacts with guanosine triphosphate. Activated G protein then activates cAMP. Next, increases in cAMP occur. Last, cAMP, the second messenger, initiates intracellular activities, including an increase in atrioventricular (AV) conduction.

6. Which system uses acetylcholine as a neurotransmitter? A. Cholinergic B. Dopaminergic C. GABA-ergic D. Noradrenergic

ANS: A Rationale: The cholinergic system uses acetylcholine as a neurotransmitter. The dopaminergic system uses dopamine as its neurotransmitter. The GABA-ergic system uses GABA as its neurotransmitter. The noradrenergic system uses norepinephrine as its neurotransmitter.

8. The nurse is preparing to administer an adrenergic medication to a client. What instructions will the nurse include in client teaching related to the drug's actions on the body? Select all that apply. A. Recommend that the client wear sunglasses. B. Instruct the client to increase fluid intake. C. Inform the client that the drug will increase the urge to urinate. D. Remind the client to report bronchoconstriction immediately. E. Monitor for abdominal cramping and diarrhea.

ANS: A, B Rationale: An adrenergic medication has the same effects on the body as the sympathetic nervous system when activated. The "fight-or-flight" response effects would include increased dilation of the pupil, which helps to see in the distance. There would be increased sweating, constriction of bladder smooth muscles, bronchodilation, and decreased gastrointestinal motility. Sunglasses protect dilated eyes. Fluid intake needs to be increased because of diaphoresis and fluid lost. The drug constricts smooth muscle of the bladder, decreasing the urge to urinate. The drug leads to bronchodilation, so suggesting that bronchoconstriction may result is not appropriate. The drug may lead to constipation rather than diarrhea, so recommending increased dietary fiber may be an appropriate intervention.

10. The nurse administers intravenous (IV) norepinephrine to the client diagnosed with shock. The nurse would predict which receptor subtypes to be activated resulting in a stimulatory response? Select all that apply. A. Alpha1 B. Alpha2 C. Beta1 D. Beta2 E. Nicotinicm

ANS: A, B, C Rationale: Norepinephrine, an adrenergic drug, acts mainly on alpha1 and alpha2 receptors, resulting in vasoconstriction of blood vessels and increasing blood pressure. It does have effects on beta1 receptors in the heart, resulting in an increase heart rate and blood flow to the heart, but not on beta2 receptors in the lungs. Nicotinicm receptors, which are cholinergic receptors located in skeletal muscles, would not be activated by an adrenergic agonist.

The nurse prepares to administer a selective alpha-adrenergic agonist medication to a client diagnosed with shock. What would the nurse consider to be therapeutic or desired effects based upon the characteristics of the prescribed medication? Select all that apply. A. Increased blood pressure B. Bronchodilation C. Increased cardiac output D. Tachycardia E. Glycogenolysis

ANS: A, C Rationale: The adrenergic medication acts as an agonist and selectively binds to the alpha1 and alpha2 receptors and elicits the physiologic responses for the receptors. The medication stimulates the activity of the sympathetic nervous system via the alpha1 receptors in smooth muscle cells leading to vasoconstriction and gastrointestinal and bladder sphincter contraction.

9. The nurse has administered a parasympathomimetic medication to a client. What assessment findings would the nurse expect following administration? Select all that apply. A. Pupils are constricted bilaterally. B. Droplets of sweat appear on the forehead and body. C. The client states, "I am able to empty my bladder more easily." D. Respirations before medication: 16 and after medication: 22. E. Pulse before medication: 90 and after medication: 70.

ANS: A, C, E Rationale: A parasympathomimetic medication has the same effects on the body as the parasympathetic nervous system when activated. The "rest or digest" response effects would include increased constriction of pupils to enable near vision. There would be a decrease in sweating since the body is at rest. The medication would also cause contraction of the bladder smooth muscles resulting in urination. With the medication, heart rate and respiratory rate would decrease.

11. The nurse administers intravenous (IV) dopamine to a client diagnosed with shock. The nurse would predict which receptor subtypes to be activated resulting in a stimulatory response? Select all that apply. A. Alpha1 B. Alpha2 C. Beta1 D. Beta2 E. Dopaminergic receptors

ANS: A, C, E Rationale: Dopamine acts like endogenous dopamine in the body and the effects depends upon the dosage. Dopamine activates alpha1 receptors resulting in vasoconstriction and increase of blood pressure and beta1 receptors increasing the heart rate, strength of heart muscle contraction, and cardiac output. Dopamine activates dopaminergic receptors, which results in vasodilation of blood vessels in the brain, kidneys, and viscera. Dopamine does not activate alpha2 or beta2 receptor.

Which outcomes should the nurse consider to be side effects of a selective cholinergic agonist based upon the characteristics of the prescribed medication? Select all that apply. A. Increased drooling B. Heart rate 110 C. Abdominal cramping D. Pupil dilation E. Blood pressure 88/50 mm Hg

ANS: A, C, E Rationale: The cholinergic medication acts as an agonist and selectively binds to the muscarinic receptors, altering the function of the receptors and eliciting the physiologic responses associated with them. The medication stimulates the activity of the parasympathetic nervous system, resulting in the side effects of sweating, increased salivation, abdominal cramping because of smooth muscle contractions in the gastric area, and low blood pressure or hypotension. Tachycardia and pupil dilation would occur when an adrenergic medication was administered, resulting in sympathetic nervous system stimulation.

5. A client has been diagnosed with Parkinson's disease. The client's spasticity is related to a decrease in what neurotransmitter? A. Acetylcholine B. Dopamine C. Adrenocorticotropic hormone D. Serotonin

ANS: B Rationale: A client with Parkinson's disease develops symptoms of spasticity related to a decrease in dopamine. A client with Parkinson's disease will have an increase in acetylcholine. Adrenocorticotropic hormone and serotonin will not be influenced in relation to the disease process.

2. A client has a decrease in calcium. Which receptor will be stimulated to increase the intracellular concentration of calcium? A. Acetylcholine B. Muscarinic C. Beta adrenergic D. Nicotinic

ANS: B Rationale: Muscarinic receptors are located in most internal organs to address the affected cells with the release of acetylcholine. Muscarinic1 receptors increase the intracellular concentration of calcium. Nicotinic receptors are located in motor and skeletal muscle. When they are activated by acetylcholine, the cell membrane depolarizes and produces muscle contraction. Acetylcholine is a neurotransmitter. Beta adrenergic is the receptor for the release of epinephrine and norepinephrine.

4. Which ion is required for neurotransmitter release from storage sites in the small sacs known as synaptic vesicles? A. Potassium B. Calcium C. Sodium D. Chloride

ANS: B Rationale: The basis for the action potential is the transient opening of ion channels. The entry of calcium ions is required for neurotransmitter release from storage sites in small sacs, called synaptic vesicles. Potassium ions are principal cations in intracellular fluid. Sodium ions are principal cations in extracellular fluid. Chloride is the major cellular ion.

The nurse prepares to administer a selective alpha1-adrenergic antagonist medication to a client diagnosed with hypertension. What would the nurse consider to be side effects based upon the characteristics of the prescribed medication? Select all that apply. A. Dry mouth B. Blood pressure (BP) lying 130/70 mm Hg, pulse 70; sitting BP 120/60, pulse 90; standing BP 100/50, pulse 110 C. Dizziness D. Reflex tachycardia E. Glucose 180 mg/dL

ANS: B, C, D Rationale: The adrenergic medication acts as an antagonist and selectively binds to the alpha1 receptors but fails to elicit the physiologic responses for the receptors. The medication inhibits the activity of the sympathetic nervous system, resulting in symptoms of the "rest or digest" response. Among the side effects is orthostatic hypotension, which results from a sudden decrease in peripheral resistance and inhibition of vascular smooth muscle.

The nurse is caring for a client who for the past several days has been receiving norepinephrine intravenously for shock. The nurse recognizes the presence of which beta-adrenergic response(s) when the client suddenly fails to respond to the prescribed dose of medication? Select all that apply. A. Hypersensitization B. Desensitization C. Up-regulation D. Down-regulation E. Antagonist

ANS: B, D Rationale: Down-regulation is also called desensitization, which occurs when high doses of an adrenergic are taken over a long period of time, causing a reduction in the number of beta receptors and their ability to stimulate adenyl cyclase. The client received the norepinephrine for several days and needed an increased dose because of desensitization. An antagonist is a medication that binds to a receptor and, as a result, inactivates the physiologic response normally associated with that receptor. Norepinephrine is an adrenergic agonist. Up-regulation is also called hypersensitization, which occurs with chronic exposure to a drug that blocks receptor function. This would cause an increase in the number of beta receptors and their ability to stimulate adenyl cyclase.

7. The nurse is caring for a client with premedication data as follows: blood pressure (BP) 88/40 mm Hg, heart rate (HR) 45, respiratory rate (RR) 12, glucose 70 mg/dL, cardiac output (CO) 3.8 L/min (normal range 4-6 L/min). The nurse would predict which assessment findings after administering a sympathomimetic to the client? Select all that apply. A. HR 40 B. BP 100/60 C. CO 3.5 L/min D. Glucose 150 mg/dL (8.32 mmol/L) E. RR 20

ANS: B, D, E Rationale: A sympathomimetic medication has the same effects on the body as the sympathetic nervous system when activated. The "stress or emergency" or also called "fight-or-flight" response effects would include increased heart rate and blood pressure, increased cardiac output, hyperglycemia, or increased glucose, and increased respirations.

3. A client has a decreased heart rate. Which receptor will activate the potassium channels to increase the cardiac output and rate? A. Acetylcholine B. Muscarinic1 C. Muscarinic2 D. Neuromuscular junctions

ANS: C Rationale: Muscarinic2 receptors activate as a result of inhibition of adenyl cyclase in the heart. Receptor stimulation also results in activation of potassium channels in cell membranes of the heart. Muscarinic1 receptors are expressed primarily in the CNS, autonomic ganglia, and the gastric and salivary glands. Activation of these receptors results from a series of processes during which phospholipids in the cell membrane and inside the cell are broken down. Acetylcholine is a neurotransmitter. Neuromuscular junctions are sites for parasympathetic response.

12. The nurse is scheduled to administer pancuronium, a neuromuscular-blocking medication, to a client receiving mechanical ventilation. The nurse would predict which receptor subtype(s) to be activated resulting in a stimulatory response? A. All muscarinic receptors B. Specifically nicotinicn receptors C. Specifically nicotinicm receptors D. Both muscarinic and nicotinic receptors

ANS: C Rationale: Pancuronium is selective in only stimulating the nicotinicm receptors of the autonomic nervous system, resulting in the paralysis of the skeletal muscles. This is beneficial in the ventilated client; complete relaxation of the muscles prevents interference with mechanical ventilation. The client can only safely receive the medication while being ventilated. The medication does not affect the other nicotinic or muscarinic receptors, so the client's body may rest and digest.

A client is experiencing stimulation of receptors in the parasympathetic nervous system. What symptom does the nurse assess in this client? A. Urinary retention B. Constipation C. Sweating D. Dry mouth

ANS: C Rationale: Stimulation of receptors in the parasympathetic nervous system produces cholinergic effects. Blockade of receptors produces anticholinergic effects. Cholinergic effects include increased secretions from glands in the lungs, stomach, intestines, and skin, including the sweat glands. Constipation, dry mouth, and urinary retention are signs of anticholinergic effects.

The nurse educates a client diagnosed with asthma concerning the prescribed selective beta2- adrenergic agonist inhaler. Which client statement indicates the need for further clarification? A. "The inhaler will cause my bronchi to dilate and make it easier for me to breathe." B. "Beta2 receptors are in the respiratory tract and the bronchi." C. "The medication will cause my heart rate to increase and will cause palpitations." D. "The medication will bind to beta2 receptors and activate the physiologic response."

ANS: C Rationale: The nurse should emphasize that the medication is selective to beta2 receptors that affect bronchodilation. The medication does not significantly activate beta1 receptors leading to tachycardia or palpitations. The definition of agonist is that the medication will bind to the beta2 receptors and activate the physiologic response, and in this case, the sympathetic nervous system.

1. During ambulation after surgery, the skeletal muscle produces contraction. What receptor is located in motor nerves and skeletal muscle? A. Acetylcholine B. Muscarinic C. Beta adrenergic D. Nicotinic

ANS: D Rationale: Nicotinic receptors are located in motor and skeletal muscle. When they are activated by acetylcholine, the cell membrane depolarizes and produces muscle contraction. Acetylcholine is a neurotransmitter. Beta adrenergic is the receptor for the release of epinephrine and norepinephrine. Muscarinic are receptors located in most internal organs to address the affected cells with the release of acetylcholine.

13. The nurse administers an anticholinergic medication to a client. The nurse would predict which receptor subtypes to be blocked? Select all that apply. A. Alpha B. Beta C. Dopaminergic D. Muscarinic E. Nicotinic

ANS: D, E Rationale: Anticholinergic medication blocks the cholinergic receptor subtypes, including muscarinic and nicotinic, resulting in blocking the parasympathetic nervous system effects. An anticholinergic does not block the adrenergic neurotransmitters—alpha, beta, and dopaminergic—found in the sympathetic nervous system.