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 8

Chapter 26, Problem 8

Respiratory acidosis develops when the blood pH is:
(a) Increased due to a decreased blood P𝒸ₒ₂ level
(b) Decreased due to an increased blood P𝒸ₒ₂ level
(c) Increased due to an increased blood P𝒸ₒ₂ level
(d) Decreased due to a decreased blood P𝒸ₒ₂ level

Verified step by step guidance

Step 1: Understand the definition of respiratory acidosis. Respiratory acidosis occurs when there is an accumulation of carbon dioxide (CO\_2) in the blood, leading to an increase in hydrogen ion concentration and thus a decrease in blood pH.

Step 2: Recall the relationship between CO\_2 and blood pH. CO\_2 reacts with water in the blood to form carbonic acid, which dissociates into hydrogen ions (H\^+) and bicarbonate (HCO\_3\^-). An increase in CO\_2 shifts this equilibrium, increasing H\^+ concentration and lowering pH.

Step 3: Analyze each option in terms of CO\_2 levels and pH changes: (a) Increased pH with decreased CO\_2 is alkalosis, not acidosis; (b) Decreased pH with increased CO\_2 matches respiratory acidosis; (c) Increased pH with increased CO\_2 is contradictory; (d) Decreased pH with decreased CO\_2 is unlikely.

Step 4: Conclude that respiratory acidosis is characterized by a decreased blood pH due to an increased blood CO\_2 level.

Step 5: Therefore, the correct description of respiratory acidosis corresponds to option (b): decreased pH due to increased blood P\_CO\_2.

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Key Concepts

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

Respiratory Acidosis

Respiratory acidosis is a condition where the blood becomes more acidic due to impaired lung function, leading to an accumulation of carbon dioxide (CO₂). This excess CO₂ increases hydrogen ion concentration, lowering blood pH below the normal range (7.35-7.45). It typically results from hypoventilation or respiratory diseases.

Blood pH and Acid-Base Balance

Blood pH measures the acidity or alkalinity of blood, with normal values around 7.4. A decrease in pH indicates acidosis, while an increase indicates alkalosis. The body maintains pH balance through respiratory and renal mechanisms that regulate CO₂ and bicarbonate levels.

Partial Pressure of Carbon Dioxide (P𝒸ₒ₂)

P𝒸ₒ₂ represents the amount of CO₂ gas dissolved in the blood and is a key factor in respiratory regulation of acid-base balance. Elevated P𝒸ₒ₂ (hypercapnia) leads to increased acidity (lower pH), while decreased P𝒸ₒ₂ (hypocapnia) causes alkalinity (higher pH).

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Partial Pressure

Related Practice

Textbook Question

The most important factor affecting the pH of body tissues is the concentration of:

(a) Lactic acid

(b) Ketone bodies,

(d) Carbon dioxide

(e) Hydrochloric acid

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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

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

(d) Increase in volume and become hypotonic to the ICF

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Textbook Question

Changes in the pH of body fluids are compensated for by all of the following except:

(a) An increase in urine output

(b) The carbonic acid–bicarbonate buffer system