The nurse administers a drug to a patient whose heart rate is bradycardic aimed at increasing heart rate and myocardial activity. What adrenergic receptor is this drug stimulating?
Beta 1
Beta 2
Alpha 2
Alpha 1
The Correct Answer is A
A) Beta 1: Beta-1 adrenergic receptors are primarily located in the heart and are responsible for increasing heart rate (chronotropy), the force of contraction (inotropy), and the conduction speed of electrical impulses within the heart (dromotropy). When a drug is given to increase heart rate and myocardial activity, it is stimulating the beta-1 receptors, which enhance the heart's performance..
B) Beta 2: Beta-2 receptors are predominantly found in smooth muscles, such as those
in the bronchi, blood vessels, and uterus. Stimulation of beta-2 receptors leads to relaxation of these muscles, including bronchodilation and vasodilation, which would not have a direct effect on increasing heart rate or myocardial activity.
C) Alpha 2: Alpha-2 receptors are primarily located in the central nervous system (CNS) and act to inhibit the release of norepinephrine, leading to a reduction in sympathetic nervous system activity. They have the opposite effect of what is desired in this case, as stimulation of alpha-2 receptors would actually lower heart rate and decrease myocardial activity, not increase it.
D) Alpha 1: Alpha-1 receptors are found in the smooth muscle of blood vessels and when stimulated, cause vasoconstriction, which increases blood pressure. While alpha-1 receptors do affect the cardiovascular system, they do not directly influence heart rate or myocardial contractility.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["A","C","E","F"]
Explanation
A) Bradycardia: Bradycardia is a common symptom of a cholinergic crisis. It results from excessive acetylcholine at the neuromuscular junction, which can overstimulate the parasympathetic nervous system, leading to a decrease in heart rate.
B) Rash: A rash is not a typical symptom of a cholinergic crisis. Rash might occur as a side effect of medications or other conditions, but it is not a hallmark feature of a cholinergic crisis in myasthenia gravis.
C) Vomiting: Vomiting is a potential symptom of a cholinergic crisis. It occurs due to the excessive stimulation of the parasympathetic nervous system, which can cause gastrointestinal distress and nausea.
D) Fever: Fever is not typically associated with a cholinergic crisis, but it can occur if there is an underlying infection or other condition. A cholinergic crisis itself usually leads to symptoms like weakness and excessive salivation, not fever.
E) Weakness: Weakness is a hallmark symptom of a cholinergic crisis, as it results from overstimulation at the neuromuscular junction, leading to muscle fatigue and paralysis. This is similar to the symptoms of myasthenia gravis, but in a cholinergic crisis, the weakness is more profound.
F) Drooling: Drooling is another common symptom of a cholinergic crisis. Excessive acetylcholine can lead to excessive salivation due to overstimulation of the parasympathetic nervous system.
Correct Answer is A
Explanation
A) Myasthenia gravis (MG):
Weakness of the extremities and diplopia (double vision) are hallmark symptoms of myasthenia gravis, an autoimmune disorder that affects the neuromuscular junction. In MG, antibodies attack acetylcholine receptors, leading to muscle weakness that worsens with activity and improves with rest. The weakness typically affects voluntary muscles, including those responsible for eye movement, which leads to symptoms such as diplopia and ptosis (drooping eyelids).
B) Multiple sclerosis (MS):
Multiple sclerosis involves the demyelination of neurons in the central nervous system, leading to a variety of neurological symptoms. While MS can cause weakness and visual disturbances, the typical symptoms of MS include fatigue, muscle spasticity, ataxia, and sensory deficits. Diplopia can occur in MS but is usually accompanied by other neurological signs such as numbness, tingling, or loss of coordination.
C) Cerebral palsy (CP):
Cerebral palsy is a group of disorders affecting movement and posture due to non-progressive brain injury or abnormal brain development, often occurring in early childhood. While CP can cause muscle weakness and coordination issues, it does not typically present with diplopia. Instead, it often involves spasticity, motor impairment, and difficulty with fine motor tasks.
D) Parkinson disease (PD):
Parkinson disease is characterized by tremors, bradykinesia (slowness of movement), rigidity, and postural instability. While PD can lead to muscle weakness and visual issues like blurred vision, it is not typically associated with diplopia as a primary symptom. The hallmark motor symptoms are primarily related to tremor and difficulty initiating movements rather than generalized weakness and double vision.
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