Which electrolyte is associated with a change in pH of blood?
Calcium
Sodium
Magnesium
Potassium
The Correct Answer is D
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.

Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A: Decreased Respirations
Decreased respirations, or a slower breathing rate, are not typically associated with acute stress. In fact, acute stress often leads to an increase in respiratory rate as part of the body’s “fight or flight” response. This response is mediated by the autonomic nervous system, which prepares the body to respond to a perceived threat by increasing heart rate, respiratory rate, and blood pressure.
Choice B: Tachycardia
Tachycardia, or an increased heart rate, is a common indicator of acute stress. When an individual experiences acute stress, the body releases stress hormones such as adrenaline and cortisol. These hormones stimulate the heart to beat faster, providing more oxygen and nutrients to the muscles and brain to prepare for a rapid response to the stressor. Tachycardia is a hallmark of the acute stress response and can be easily measured by checking the pulse.
Choice C: Hair Loss
Hair loss is generally associated with chronic stress rather than acute stress. Chronic stress can lead to conditions such as telogen effluvium, where hair follicles enter a resting phase and hair falls out more easily. However, this process takes time and is not an immediate response to acute stress. Therefore, hair loss is not a reliable indicator of acute stress.
Choice D: Pupil Constriction
Pupil constriction, or miosis, is not typically associated with acute stress. In fact, acute stress usually causes pupil dilation (mydriasis) as part of the “fight or flight” response. Dilated pupils allow more light to enter the eyes, improving vision and awareness of the surroundings. Pupil constriction is more commonly associated with relaxation or the body’s “rest and digest” state, mediated by the parasympathetic nervous system.
Correct Answer is A
Explanation
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.
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