What is the primary anion of the ECF?

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: 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.

Correct Answer: D

Rationale: The correct answer is D because when the rate of CO removal by the lungs is less than the rate of CO production by the tissues, more CO builds up in the body. This excess CO leads to increased generation of H+ ions due to the breakdown of CO into H+ ions and carbon. This acidic environment from the increased H+ ions can disrupt the body's pH balance. Choice A is incorrect because the rate of protein catabolism and anabolism does not directly impact the generation of H+ from CO. Choice B is also incorrect because the speed of protein breakdown and synthesis does not affect the generation of H+ from CO. Choice C is incorrect because the rate of CO removal by the lungs being higher than CO production does not lead to an increase in H+ generation.

Correct Answer: B

Rationale: The correct answer is B: Chemical buffer systems respond to changes in acid or base levels. This is because chemical buffer systems work by absorbing or releasing H+ ions to maintain a stable pH in the body. They act immediately to prevent drastic changes in pH levels. A is incorrect because chemical buffer systems act almost instantaneously, not in one to three minutes. C is incorrect because chemical buffer systems do not directly promote H+ excretion by the kidneys; that is the role of the renal system. D is incorrect because chemical buffer systems do not directly stimulate the respiratory center; that is the role of the respiratory system.