Which of the following physiologic principles would be considered a function of the somatic nervous system?
the patella reflex "knee jerk" activated by tapping the patella tendon
abdominal viscera the beginning of depolarization in the cardiac conduction of impulses
the act of typing a report using a computer keyboard
withdrawing the hand after touching a hot surface
The Correct Answer is C
A) The patella reflex ("knee jerk") activated by tapping the patella tendon: The patellar reflex is a monosynaptic spinal reflex that involves the somatic nervous system but is a reflex action rather than a voluntary motor function. The somatic nervous system governs voluntary movements, but reflex actions like the patellar reflex are involuntary responses that do not require higher brain input, though they involve somatic motor pathways.
B) Abdominal viscera the beginning of depolarization in the cardiac conduction of impulses: This process is primarily under the control of the autonomic nervous system (ANS), not the somatic nervous system. The ANS regulates involuntary processes like heart rate and digestion, while the somatic nervous system controls voluntary movements and somatic sensation.
C) The act of typing a report using a computer keyboard: Typing is a voluntary motor activity, controlled by the somatic nervous system. The somatic system is responsible for conscious, voluntary actions such as moving muscles in the arms, hands, and fingers to type. This is the most accurate example of a somatic function.
D) Withdrawing the hand after touching a hot surface: This is a reflex action known as the "withdrawal reflex," which involves the somatic nervous system. However, it is an involuntary action triggered by a sensory stimulus. While it does involve the somatic system, it is not a voluntary action like typing, and reflexes are considered part of the automatic response mechanisms.
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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 A
Explanation
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.
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