Why is it not accurate to refer to body fluids as "body water"?

Correct Answer: B

Rationale: The correct answer is B because body fluids encompass more than just water, including substances like sweat. Sweat is an example of body fluid that is not solely composed of water but also contains electrolytes and other solutes. This distinction is important because body fluids are not limited to pure water but consist of various components that serve different functions in the body. Choices A, C, and D are incorrect because they do not accurately reflect the comprehensive nature of body fluids. Choice A focuses on internal body cavities, which are still considered part of the body, while choice C incorrectly states that body fluid is lipid-based, and choice D oversimplifies body fluids as just water and solutes.

Correct Answer: B

Rationale: The correct answer is B: chloride ion. In the extracellular fluid (ECF), chloride ion is the primary anion that helps maintain electrolyte balance and osmotic pressure. It is the most abundant anion in the ECF and plays a crucial role in acid-base balance. Bicarbonate ion is an important buffer in the blood but not the primary anion in the ECF. Phosphate ion is more abundant in intracellular fluid than extracellular fluid. Potassium ion is a cation, not an anion, and is primarily found inside cells, not in the ECF.

Correct Answer: A

Rationale: The correct answer is A: to maintain blood pressure. Extracellular fluid volume regulation is crucial for maintaining blood pressure within a normal range. Any imbalance in extracellular fluid volume can lead to changes in blood pressure, potentially causing issues like hypotension or hypertension. Adequate blood pressure is necessary for proper perfusion of organs and tissues. Choice B (to maintain adequate urine formation) is incorrect because extracellular fluid volume regulation primarily affects blood pressure, not urine formation. Choice C (to prevent changes in ICF osmolarity) is incorrect because extracellular fluid volume regulation does not directly impact intracellular fluid osmolarity. Choice D (to prevent cells from swelling or shrinking) is incorrect because intracellular fluid volume regulation, not extracellular fluid volume, is primarily responsible for preventing cellular swelling or shrinking.

Correct Answer: C

Rationale: The correct answer is C because an increase in sodium reabsorption would be triggered by a drop in arterial blood pressure, not a decrease. When arterial blood pressure drops, the body aims to retain sodium and water to increase blood volume and pressure. Choices A, B, and D are incorrect as they are all actions that would be triggered by a drop in arterial blood pressure. A decrease in glomerular filtration rate (GFR) helps conserve fluids and maintain blood pressure, release of aldosterone promotes sodium and water retention, and a decrease in chloride excretion also helps in retaining fluids. Therefore, an increase in sodium reabsorption is the action NOT triggered by a drop in arterial blood pressure.

Correct Answer: D

Rationale: The correct answer is D: water retention. Water intoxication leads to dilution of electrolytes in the body, causing intracellular fluid (ICF) hypotonicity and circulatory extracellular fluid (ECF) hypotonicity. Excess free water intake can overwhelm the kidneys' ability to excrete it, resulting in hyponatremia. Water retention, on the other hand, implies the body is holding onto water, which is not a characteristic of water intoxication where excess water is typically excreted. Therefore, water retention does not occur during water intoxication.