Many of the clinical manifestations for acute stress are attributed to activation of the sympathetic nervous system and are mediated by:
Norepinephrine
Cortisol
ACTH
Glucagon
The Correct Answer is A
Choice A Reason:
Norepinephrine is a key neurotransmitter released by the sympathetic nervous system during the “fight-or-flight” response. It plays a crucial role in preparing the body to respond to stress by increasing heart rate, blood pressure, and blood flow to muscles, as well as dilating the airways. These physiological changes are essential for coping with acute stress.
Choice B Reason:
Cortisol is a hormone released by the adrenal glands in response to stress, but it is primarily associated with the hypothalamic-pituitary-adrenal (HPA) axis rather than the sympathetic nervous system. While cortisol contributes to the body’s overall stress response by increasing blood sugar levels and suppressing the immune system, it is not the primary mediator of the acute “fight-or-flight” response.
Choice C Reason:
ACTH (adrenocorticotropic hormone) is a hormone produced by the pituitary gland that stimulates the adrenal glands to release cortisol. It is part of the HPA axis and plays a role in the body’s long-term stress response, but it is not directly involved in the immediate activation of the sympathetic nervous system.
Choice D Reason:
Glucagon is a hormone produced by the pancreas that raises blood glucose levels by promoting the breakdown of glycogen to glucose in the liver. While it can be involved in the body’s response to stress by ensuring an adequate supply of glucose, it is not a primary mediator of the acute stress response mediated by the sympathetic nervous system.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A: Calcium
Calcium plays a crucial role in various physiological processes, including muscle contraction, blood clotting, and nerve transmission. While calcium is essential for maintaining overall health, it is not directly associated with changes in blood pH. Calcium levels are tightly regulated by hormones such as parathyroid hormone (PTH) and calcitonin, but these do not significantly influence blood pH.
Choice B: Sodium
Sodium is a major extracellular electrolyte that helps regulate fluid balance, nerve function, and muscle contraction. Although sodium is vital for maintaining osmotic balance and blood pressure, it does not directly affect blood pH. Sodium levels are primarily controlled by the kidneys and hormones like aldosterone, which do not have a direct impact on the acid-base balance of the blood.
Choice C: Magnesium
Magnesium is involved in over 300 biochemical reactions in the body, including protein synthesis, muscle and nerve function, and blood glucose control. While magnesium is important for overall health, it does not have a direct role in altering blood pH. Magnesium levels are regulated by the kidneys and are essential for maintaining normal muscle and nerve function, but they do not directly influence the acid-base balance.
Choice D: Potassium
Potassium is a key intracellular electrolyte that plays a significant role in maintaining the acid-base balance of the blood. Changes in potassium levels can affect the pH of the blood. For example, hyperkalemia (high potassium levels) can lead to acidosis, while hypokalemia (low potassium levels) can lead to alkalosis. Potassium helps regulate the hydrogen ion concentration in the blood, which directly impacts the pH. Therefore, potassium is the electrolyte most closely associated with changes in blood pH.
Correct Answer is D
Explanation
Choice A: Minimal Effect on Vessels
A reduction in blood pH, which indicates acidosis, does not have a minimal effect on blood vessels. Acidosis can significantly impact vascular tone and function. Therefore, this choice is incorrect as it underestimates the physiological changes that occur in response to a decrease in pH.
Choice B: No Effect on Vessels
Similarly, stating that a reduction in blood pH has no effect on vessels is inaccurate. Blood pH is tightly regulated, and deviations from the normal range (7.35-7.45) can lead to significant physiological responses. Acidosis can alter vascular tone, making this choice incorrect.
Choice C: Vasodilation
While vasodilation can occur in response to certain conditions, a reduction in blood pH typically leads to vasoconstriction rather than vasodilation. Vasodilation is more commonly associated with an increase in blood pH (alkalosis) or other factors such as increased levels of nitric oxide or prostaglandins.
Choice D: Vasoconstriction
When the pH of blood reduces, indicating acidosis, it often leads to vasoconstriction. This response is mediated by chemoreceptors that detect changes in pH and stimulate the vasomotor center to increase vascular tone. Vasoconstriction helps to maintain blood pressure and ensure adequate perfusion of vital organs during acidosis. Therefore, this is the correct answer.
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