The lab demonstrated an experiment where the volunteer exhaled into a basic solution with a pH indicator. How did the expired air affect the solution?
It decreased the pH of the solution as it increased the amount of bicarbonate
There was no change.
It decreased the pH of the solution as it increases CO2 in the solution
It increased the pH of the solution as it increases CO2 in the solution
It increased the pH of the solution as it increased the amount of bicarbonate
The Correct Answer is C
A. It decreased the pH of the solution as it increased the amount of bicarbonate: While bicarbonate is part of the buffering system, the immediate reduction in pH is driven by the liberation of hydrogen ions. Bicarbonate itself acts as a conjugate base. The acidification is a result of the formation of carbonic acid.
B. There was no change: Exhaled breath contains a significant partial pressure of carbon dioxide, which is chemically active in aqueous solutions. The interaction between carbon dioxide and water inevitably produces weak acid. This chemical reaction alters the pH and triggers a color change.
C. It decreased the pH of the solution as it increases CO2 in the solution: Dissolved carbon dioxide reacts with water to form carbonic acid, which dissociates into hydrogen and bicarbonate ions. The increased concentration of free protons raises the acidity of the solution. This lower pH is detected by the indicator.
D. It increased the pH of the solution as it increases CO2 in the solution: Carbon dioxide is an acid anhydride and cannot increase the alkalinity of a solution. An increase in carbon dioxide concentration shifts the chemical equilibrium toward the production of more acidic products. This results in a lower pH value.
E. It increased the pH of the solution as it increased the amount of bicarbonate: Higher bicarbonate levels generally contribute to alkalinity or buffering capacity. However, the process of exhaling into the solution primarily introduces carbon dioxide, which acts to acidify the environment. It does not lead to an increase in pH.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. The cell begins to divide uncontrollably: Uncontrolled cellular proliferation is typically a result of genetic mutations or dysregulated signaling pathways rather than acute intracellular dehydration. Dehydration generally inhibits metabolic activity and halts the cell cycle. Chronic water deficit leads to apoptosis rather than hyperplasia.
B. The cytosol becomes overly concentrated with solutes, impairing function: Loss of intracellular water increases the molarity of cytosolic electrolytes and proteins, leading to cellular crenation. This hypertonic state disrupts the delicate spatial arrangement of organelles and molecular interactions. Essential biochemical pathways, including protein synthesis, become severely inhibited.
C. The cytosol becomes diluted and inactive: Dilution of the cytosol occurs during cellular swelling or water intoxication, where free water influx exceeds solute concentration. Low intracellular water levels result in a highly concentrated, not diluted, environment. Inactivity in this context stems from molecular crowding.
D. The cell gains energy efficiency: Dehydration places significant metabolic stress on the cell, requiring active transport mechanisms to attempt to restore osmotic balance. This increased workload consumes adenosine triphosphate and reduces overall metabolic efficiency. A dehydrated state is physiologically taxing and potentially lethal.
Correct Answer is D
Explanation
A. Hyperthermia: Barbiturate toxicity typically leads to central nervous system depression and a decrease in metabolic rate, which can result in hypothermia. While drug reactions vary, the primary life-threatening complication is respiratory failure. It does not typically trigger a primary hyperthermic response.
B. Hypoxia: While hypoxia occurs secondary to hypoventilation, hypercapnia is the direct respiratory acid-base consequence of reduced alveolar ventilation. Barbiturates suppress the medullary respiratory centers, specifically impairing the clearance of carbon dioxide. This leads to a primary elevation in arterial carbon dioxide levels.
C. Hypocapnia: This condition involves abnormally low levels of carbon dioxide in the blood, usually caused by hyperventilation or anxiety. Barbiturates are sedative-hypnotics that slow the breathing rate significantly. They would never cause a decrease in carbon dioxide under standard toxicological conditions.
D. Hypercapnia: Barbiturates depress the drive to breathe, leading to inadequate gas exchange and the systemic retention of carbon dioxide. This elevation in arterial carbon dioxide is the hallmark of respiratory depression. It leads to a concomitant drop in blood pH as carbonic acid levels rise.
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