Q: Which equation best represents the relationship between plasma osmolarity, sodium concentration, and water balance?

$$Osmolarity = 2 \times [Na^+] + \frac{Glucose}{18} + \frac{BUN}{2.8}$$

Q: Which of the following formulas can be used to estimate the change in plasma sodium concentration after infusion of a given volume of hypotonic fluid?

$$\Delta [Na^+] = \frac{Infused\ Volume \times [Na^+]_{infusate}}{Total\ Body\ Water + Infused\ Volume}$$

Question 1

Which hormone is primarily responsible for increasing sodium reabsorption in the distal convoluted tubule of the nephron?

Accepted Answer

Aldosterone

Question 2

A patient presents with hyponatremia after excessive water intake. Which of the following best explains the physiological consequence?

Accepted Answer

Cells swell due to water entering the intracellular space

Question 3

Which equation best represents the relationship between plasma osmolarity, sodium concentration, and water balance?

Accepted Answer

$$Osmolarity = 2 	imes [Na^+] + \frac{Glucose}{18} + \frac{BUN}{2.8}$$

Question 4

A patient with hyperaldosteronism is likely to exhibit which of the following symptoms?

Accepted Answer

Hypernatremia and hypertension

Question 5

Which of the following mechanisms is activated in response to decreased blood volume and pressure?

Accepted Answer

Activation of the renin-angiotensin-aldosterone system (RAAS)

Question 6

A patient is found to have hypervolemia. Which of the following is the most likely cause?

Accepted Answer

Excessive sodium retention

Question 7

Which of the following best describes the effect of antidiuretic hormone (ADH) on water balance?

Accepted Answer

ADH increases water reabsorption in the collecting ducts

Question 8

Which of the following is a direct effect of atrial natriuretic peptide (ANP) on the kidneys?

Accepted Answer

Increased sodium excretion

Question 9

A patient with severe dehydration is likely to have which of the following laboratory findings?

Accepted Answer

High plasma sodium and high plasma osmolarity

Question 10

Which of the following scenarios would most likely trigger the release of renin from the juxtaglomerular cells?

Accepted Answer

Decreased blood pressure and decreased sodium concentration

Question 11

A patient with SIADH (syndrome of inappropriate antidiuretic hormone secretion) is most likely to develop which electrolyte imbalance?

Accepted Answer

Hyponatremia

Question 12

Which of the following best explains the physiological response to hypernatremia?

Accepted Answer

Water moves from the intracellular to the extracellular compartment

Question 13

Which of the following is the correct sequence of events in the renin-angiotensin-aldosterone system (RAAS)?

Accepted Answer

Renin → Angiotensin I → Angiotensin II → Aldosterone

Question 14

A patient with Addison's disease (adrenal insufficiency) is likely to present with which of the following?

Accepted Answer

Hyponatremia and hypotension

Question 15

Which of the following formulas can be used to estimate the change in plasma sodium concentration after infusion of a given volume of hypotonic fluid?

Accepted Answer

$$\Delta [Na^+] = \frac{Infused\ Volume 	imes [Na^+]_{infusate}}{Total\ Body\ Water + Infused\ Volume}$$

Question 16

Which of the following is a common cause of hypervolemic hyponatremia?

Accepted Answer

Congestive heart failure

Question 17

Which of the following best describes the effect of aldosterone on potassium balance?

Accepted Answer

Aldosterone increases potassium excretion in the nephron

Question 18

A patient with severe vomiting is at risk for which of the following electrolyte imbalances?

Accepted Answer

Hyponatremia and metabolic alkalosis

Question 19

Which of the following is the most immediate effect of increased plasma osmolarity?

Accepted Answer

Stimulation of thirst and ADH release

Question 20

A patient with diabetes insipidus is most likely to present with which of the following laboratory findings?

Accepted Answer

High plasma sodium and high urine output

Role of Sodium and Fluid Balance in Human Anatomy & Physiology

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