Which of the following catecholamines may have a vasodilator effect on renal blood vessels and be prescribed for a client in shock who are experiencing renal insufficiency manifestations?
Norepinephrine
Dopamine
Acetylcholine
Enkephalin
The Correct Answer is B
A) Norepinephrine: Norepinephrine is a potent vasoconstrictor primarily used in cases of shock to increase blood pressure by constricting blood vessels. However, it does not have a vasodilatory effect on renal blood vessels. Instead, it tends to decrease renal perfusion due to its strong vasoconstrictor properties, which could worsen renal insufficiency.
B) Dopamine: Dopamine is a catecholamine that has a dose-dependent effect on various receptors. At low doses, dopamine specifically acts on dopaminergic receptors in the kidneys, leading to vasodilation of renal blood vessels, which can improve renal perfusion. This makes it particularly useful in treating shock when there is concern about renal insufficiency or reduced kidney function.
C) Acetylcholine: Acetylcholine is a neurotransmitter of the parasympathetic nervous system, not a catecholamine. It is involved in promoting various physiological effects such as slowing the heart rate and stimulating digestive processes, but it does not have a specific role in vasodilation of renal blood vessels or shock management.
D) Enkephalin: Enkephalins are endogenous peptides involved in the regulation of pain and stress responses. They do not have a direct effect on vasodilation of renal blood vessels. Enkephalins are not typically used to treat shock or manage renal insufficiency.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A) They increase norepinephrine at the neuromuscular junction: Anticholinergic agents do not directly increase norepinephrine at the neuromuscular junction. Instead, they work by blocking acetylcholine receptors (specifically muscarinic receptors) in the parasympathetic nervous system, which reduces parasympathetic activity. Norepinephrine is primarily involved in the sympathetic nervous system, not the action of anticholinergics.
B) They act to block the effects of the parasympathetic nervous system: This is the correct explanation. Anticholinergic agents work by inhibiting the action of acetylcholine at muscarinic receptors, which are part of the parasympathetic nervous system. By blocking these receptors, anticholinergics reduce parasympathetic effects such as slowing of the heart rate, increased glandular secretions, and smooth muscle contraction, leading to effects like increased heart rate, dry mouth, and bronchodilation.
C) They compete with serotonin for muscarinic acetylcholine receptor sites: Anticholinergic drugs do not interact with serotonin receptors. They specifically target muscarinic acetylcholine receptors, which are involved in parasympathetic responses. Serotonin is a different neurotransmitter, and while some drugs may affect both serotonin and acetylcholine pathways, anticholinergic agents do not compete with serotonin at these receptor sites.
D) They block nicotinic receptors: Anticholinergics typically block muscarinic receptors, not nicotinic receptors. Nicotinic receptors are involved in the transmission of signals at the neuromuscular junction and in the autonomic ganglia, while muscarinic receptors are primarily involved in parasympathetic functions. Blocking nicotinic receptors would have different effects and is not the action of anticholinergic agents.
Correct Answer is C
Explanation
A) GABA-ergic:
GABA-ergic neurons use gamma-aminobutyric acid (GABA) as their neurotransmitter, not acetylcholine (ACh). GABA is the main inhibitory neurotransmitter in the brain, playing a crucial role in reducing neuronal excitability.
B) Dopaminergic:
Dopaminergic neurons release dopamine as their neurotransmitter. Dopamine is involved in several critical functions, including movement, reward, and regulation of mood. Since acetylcholine is not involved in dopaminergic transmission, this is not the correct answer.
C) Cholinergic:
Cholinergic neurons use acetylcholine (ACh) as their neurotransmitter. These neurons are involved in many functions, including muscle activation (in the somatic nervous system), as well as modulating parasympathetic responses in the autonomic nervous system.
D) Serotonergic:
Serotonergic neurons release serotonin (5-HT), which is a neurotransmitter involved in regulating mood, appetite, sleep, and other functions. Acetylcholine is not involved in serotonergic transmission
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