Pathophysiology - Ch. 25: Acid-Base Homeostasis & Imbalances (Study Guide)

For proper pH balance within the human body, what is the ratio of bicarbonate ions to carbonic acid molecules? A. 1 bicarbonate ion to 10 carbonic acid molecules B. 20 bicarbonate ions to 1 carbonic acid molecule C. 1 bicarbonate ion to 20 carbonic acid molecules D. 10 bicarbonate ions to 1 carbonic acid molecule

B. 20 bicarbonate ions to 1 carbonic acid molecule The pH of any fluid is determined by the relative amounts of acids and bases contained in it. For the pH of the blood to be within the normal range, the ratio of bicarbonate ions to carbonic acid molecules must be 20:1. The other ratios would not maintain normal pH.

An acid accepts hydrogen ions. (T/F)

False

The normal ration of bicarbonate to carbonic acid is 10:1. (T/F)

False

The pH measured in the blood is always the same as that within cerebrospinal fluid and cells. (T/F)

False

PaCO2: 30 mm Hg (Normal, High, Low)

Low

When two primary imbalances develop simultaneously due to two different pathologies, it is called a __________ ___________ ____________.

Mixed (Combined) Acid-Base Balance

A pH buffer releases H+ when the pH is high and binds H+ when the pH is low. (T/F)

True

H+ in the urine can be buffered to form ammonium ions. (T/F)

True

The bicarbonate buffer system is the most important pH buffer in the extracellular fluid. (T/F)

True

The kidneys control the level of bicarbonate in the extracellular fluid. (T/F)

True

When the pH is lower than the normal serum range, it is called acidic. (T/F)

True

In general, acidosis produces central nervous system __________, and alkalosis produces central nervous ___________.

depression, excitation

When the mother of a child in the ER hyperventilates due to anxiety, she may develop a ____________ _____________.

respiratory alkalosis

A normal blood pH can be maintained despite variances in HC03, and carbonic acid as long as their ratio is maintained at ____________.

20:1

Which statement regarding age related changes to acid-base homeostasis is true of the older adult? (Select all that apply.) A. Chronic laxative overuse may contribute to metabolic acidosis. B. Ability to correct respiratory acidosis is delayed in the older adult. C. Older adults are at increased risk of respiratory acidosis from barbiturate use. D. Older adults experience an increased risk for metabolic acidosis from acid accumulation. E. Ammonia production is decreased by normal aging and often results in metabolic acidosis.

A. Chronic laxative overuse may contribute to metabolic acidosis. B. Ability to correct respiratory acidosis is delayed in the older adult. C. Older adults are at increased risk of respiratory acidosis from barbiturate use. D. Older adults experience an increased risk for metabolic acidosis from acid accumulation. Diarrhea from chronic laxative overuse may contribute to metabolic acidosis. The chemoreceptor response to increased PaCO2 (hyperventilation) is delayed in older adults, which may delay their ability to correct respiratory acidosis. Older adults are at increased risk of respiratory depression (and thus respiratory acidosis) from barbiturates because of increased drug half-life. Older adults’ kidneys are less able to excrete a large acid load, which increases the risk for metabolic acidosis from acid accumulation. Infants younger than 1 month have a reduced ability to excrete a large acid load; their kidneys are less able to reabsorb bicarbonate, they produce less ammonia, and urinary buffers are limited in quantity. These factors increase the risk of metabolic acidosis from acid accumulation.

How do the kidneys work to neutralize metabolic acidosis or alkalosis? A. If metabolic alkalosis exists, the kidneys slow their acid excretion. B. If metabolic alkalosis exists, the kidneys slow their acid retention. C. If metabolic acidosis exists, the kidneys slow their acid excretion. D. If metabolic acidosis exists, the kidneys increase their acid retention.

A. If metabolic alkalosis exists, the kidneys slow their acid excretion. If metabolic alkalosis exists in the body, the kidneys slow their acid excretion mechanisms to allow acid to accumulate to normal levels. If metabolic alkalosis exists in the body, the kidneys do not slow their acid retention. If metabolic acidosis exists in the body, the kidneys decrease their acid retention to allow the body to return to normalized values.

Which of the following statements regarding respiratory acidosis is true? A. It can occur in a prolonged, severe asthma attack B. The pH is elevated C. A decreased respiratory rate would be compensatory D. There is an increase in neuron excitability in motor neurons

A. It can occur in a prolonged, severe asthma attack

The kidneys excrete acids that include which of the following? (Select all that apply.) A. Lactic B. Carbonic C. Metabolic D. Phosphoric E. Hydrochloric

A. Lactic C. Metabolic D. Phosphoric E. Hydrochloric Lactic acid is a metabolic acid. The kidneys normally excrete metabolic acids. Acids that are not carbonic acid are called metabolic acids because cells continuously produce them during normal metabolism. The kidneys normally excrete metabolic acids. Phosphoric acid is a metabolic acid. The kidneys normally excrete metabolic acids. Hydrochloric acid is a metabolic acid. The kidneys normally excrete metabolic acids. The kidneys can excrete any acid from the body except carbonic acid, which is excreted solely by the lungs. If a metabolic acid begins to accumulate in the blood, the kidneys increase their acid excretion mechanisms to correct the problem.

Which of the following arterial blood gases would be categorized as compensated metabolic acidosis? A. pH 7.39, PaCO2 32, HCO3 18 B. pH 7.31, PaCO2 37, HCO3 18 C. pH 7.45, PaCO2 32, HC03 23 D. pH 7.40, PaCO2 39, HC03 24

A. pH 7.39, PaCO2 32, HCO3 18

Which serum value is a reflection of the effectiveness of the kidney's ability to properly maintain serum metabolic pH? A. (H+) molecule B. Bicarbonate (HCO3-) C. Carbon dioxide (CO2) D. Carbonic acid (H2CO3)

B. Bicarbonate (HCO3-) Bicarbonate (HCO3-) is returned to the blood simultaneously at the glomerulus during acid excretion for each (H+) molecule that is secreted into the renal tubular fluid. Net (H+) excretion can be accomplished by being attached to ammonia (ammonium ions NH4). (H+) molecule is not involved in serum pH maintenance. Carbon dioxide (CO2) and carbonic acid (H2CO3) are not involved in serum metabolic pH maintenance.

Which statement concerning the location of specific buffers is correct? (Select all that apply.) A. Protein buffers are found in urine. B. Phosphate buffers are found in the intracellular space. C. Hemoglobin buffers are found inside the erythrocytes. D. Bicarbonate buffers are found in the extracellular space. E. Protein buffers are found in the intracellular compartment.

B. Phosphate buffers are found in the intracellular space. C. Hemoglobin buffers are found inside the erythrocytes. D. Bicarbonate buffers are found in the extracellular space. E. Protein buffers are found in the intracellular compartment. Bicarbonate buffers are found in the extracellular space. Phosphate buffers are found in the intracellular space and urine. Hemoglobin buffers are found inside the erythrocytes. Protein buffers are found in the intracellular and vascular compartments. Protein buffers are not found in human urine.

Which statement is true regarding indicators? A. The indicator of the respiratory component of regulating serum pH is the concentration of plasma bicarbonate ions (HCO3-). B. The indicator of the respiratory component of regulating serum pH is the concentration of the partial pressure of carbon dioxide (CO2). C. The indicator of the metabolic component of regulating serum pH is the concentration of the partial pressure of CO2 in the blood. D. The indicator of a buffer system working properly is to take up a hydrogen ion when the fluid is too alkaline.

B. The indicator of the respiratory component of regulating serum pH is the concentration of the partial pressure of carbon dioxide (CO2). The partial pressure of carbon dioxide (CO2) in arterial blood is the indicator of the respiratory component of acid-base balance, not HCO3-. The plasma bicarbonate ion (HCO3-) concentration is an indicator of the renal (metabolic) component of acid-base balance. The plasma bicarbonate ion (HCO3-) concentration is an indicator of the renal (metabolic) component of acid-base balance, not CO2. Each buffer system consists of a weak acid, which releases hydrogen ions when the fluid is too alkaline, and a base, which takes up hydrogen ions when the fluid is too acidic.

In response to chronically elevated PaCO2, the kidneys would be expected to compensate by A. excreting more bicarbonate B. producing more bicarbonate C. reabsorbing more hydrogen ions D. filtering more bicarbonate

B. producing more bicarbonate

Metabolic acidosis is associated with all of the following except A. diarrhea B. vomiting C. end-stage kidney disease D. ketoacidosis

B. vomiting

A blood gas with pH 7.24, PaC02 58, and HC03 24 would be categorized as A. metabolic acidosis B. metabolic alkalosis C. respiratory acidosis D. respiratory alkalosis

C. respiratory acidosis

The normal adult pH in the blood is A. 7.30 B. Less than 6.9 C. Greater than 7.8 D. Between 7.35 and 7.45

D. Between 7.35 and 7.45 An acceptable range is 7.35 to 7.45. 7.30 is slightly below the normal range. If the blood becomes too acidic (less than 6.9) death is likely. If the blood becomes too alkaline (greater than 7.8) death is likely.

Which statement is true regarding carbonic acid (H2CO3)? A. If body fluids are too alkaline, carbonic acid is excreted through the respiratory system in the form of carbon dioxide and water. B. If body fluids are too alkaline, carbonic acid is retained through the respiratory system in the form of carbon dioxide and water. C. If body fluids are too acidic, carbonic acid is retained through the respiratory system in the form of carbon dioxide and water. D. If body fluids are too acidic, carbonic acid is excreted through the respiratory system in the form of carbon dioxide and water.

D. If body fluids are too acidic, carbonic acid is excreted through the respiratory system in the form of carbon dioxide and water. If too much acid is present, bicarbonate (HCO3) picks up a hydrogen (H+) molecule to form carbonic acid (H2CO3), and with the help of the enzyme called carbonic anhydrase, the carbonic acid is then excreted through the respiratory system in the form of carbon dioxide (CO2) and water (H2O). The other statements do not reflect effective utilization of carbonic acid (H2CO3).

When carbonic acid begins to accumulate in the blood, the individual's respirations will A. Increase, and the depth decrease B. Decrease, and the depth increase C. Decrease, and the depth decrease D. Increase, and the depth increase

D. Increase, and the depth increase The respiratory system adjusts the amount of carbonic acid that remains in the body when there is an excess; therefore the rate and depth of respirations will increase so that the excess carbonic acid is removed. Increased respirations and decreased depth does not occur; it would not resolve the existing problem. Decreased respirations and increased depth does not occur; it would not resolve the existing problem. If too little carbonic acid is present in the blood, the rate and depth of the respirations will decrease to retain carbonic acid until it is once more present in normal amounts.

The role of lungs in maintaining acid-base balance includes A. elimination of metabolic acids B. elimination of excess H+ C. production of bicarbonate D. elimination of carbonic acids

D. elimination of carbonic acids

Arterial HC03: 24 mEq/L (Normal, High, Low)

Normal

Arterial pH: 7.38 (Normal, High, Low)

Normal