Ch. 27 Fluids & Electrolytes

Martini - Fundamentals of Anatomy & Physiology 11th Edition

Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089Not the one you use?Change textbook

Martini, Nath, Bartholomew 11th Edition

Ch. 27 Fluids & Electrolytes

Problem 11

Chapter 26, Problem 11

Drinking a solution hypotonic to the ECF causes the ECF to:
(a) Increase in volume and become hypertonic to the ICF
(b) Decrease in volume and become hypertonic to the ICF
(c) Decrease in volume and become hypotonic to the ICF
(d) Increase in volume and become hypotonic to the ICF

Verified step by step guidance

Step 1: Understand the terms involved. The ECF (extracellular fluid) is the fluid outside cells, and the ICF (intracellular fluid) is the fluid inside cells. 'Hypotonic' means having a lower solute concentration compared to another solution, while 'hypertonic' means having a higher solute concentration.

Step 2: Recognize that drinking a hypotonic solution means introducing fluid with lower solute concentration than the ECF into the body, which will dilute the ECF, lowering its solute concentration.

Step 3: Since the ECF solute concentration decreases, water will move by osmosis from the ECF into the ICF (cells) because water moves from areas of lower solute concentration to higher solute concentration to balance osmotic pressure.

Step 4: As water moves into the cells, the volume of the ECF decreases because fluid is leaving the extracellular space and entering the intracellular space.

Step 5: Because the ECF solute concentration is now lower than that of the ICF, the ECF becomes hypotonic relative to the ICF.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Extracellular Fluid (ECF) and Intracellular Fluid (ICF) Compartments

The body’s fluids are divided mainly into ECF (outside cells) and ICF (inside cells). Understanding their volumes and solute concentrations is essential because fluid shifts between these compartments depend on osmotic gradients created by solute differences.

Tonicity and Its Effect on Cell Volume

Tonicity refers to the relative concentration of solutes in a solution compared to another solution, affecting water movement. A hypotonic solution has lower solute concentration, causing water to move into cells, potentially increasing cell volume and altering ECF volume and tonicity.

Osmosis and Fluid Movement Across Cell Membranes

Osmosis is the passive movement of water across a semipermeable membrane from a region of lower solute concentration to higher solute concentration. When hypotonic fluid is ingested, water moves from ECF into ICF, changing volumes and solute concentrations in both compartments.

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Direction of Osmosis

Related Practice

Textbook Question

In a protein buffer system, if the pH increases:

(a) The protein acquires a hydrogen ion from carbonic acid

(b) Hydrogen ions are buffered by hemoglobin molecules

(d) A chloride shift occurs

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Textbook Question

Metabolic alkalosis occurs when:

(a) Bicarbonate ion concentrations become elevated

(b) A severe bicarbonate loss occurs

(d) Ketone bodies are generated in abnormally large quantities

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Textbook Question

Identify four hormones that mediate major physiological adjustments affecting fluid and electrolyte balance. What are the primary effects of each hormone?

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Textbook Question

The osmotic concentration of the ECF decreases if an individual gains water without a corresponding:

(a) Gain of electrolytes

(b) Loss of water

(d) All of these

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Textbook Question

When the pH of body fluids begins to decrease, free amino acids and proteins will

(a) Release a hydrogen from the carboxyl group

(b) Release a hydrogen from the amino group

(d) Bind a hydrogen at the amino group