26. Fluid and Electrolyte Balance, Acid Base Balance

What is the main buffer system of the ECF?

a. Protein buffer system

b. Carbonic acid–bicarbonate ion buffer system

c. Phosphate buffer system

d. None of the above

Explain what happens to the pH of a buffered solution when hydrogen ions are added. Why does this happen?

An increase in ventilation ________ the pH of the blood due to a/an ________ of carbon dioxide in the blood. A decrease in ventilation ________ the pH of the blood due to a/an ________ of carbon dioxide in the blood.

Which of the following mechanisms is/are used by the kidneys to regulate the pH of the blood? Circle all that apply.

a. Hydrogen ions are secreted from the proximal and distal tubules and the collecting system.

b. Hydrogen ions are reabsorbed from the nephron loop.

c. New bicarbonate ions are formed from glutamine and carbon dioxide in the interstitial fluid that enters proximal tubule cells.

d. Bicarbonate ions can be secreted.

e. Bicarbonate ions are reabsorbed directly from the filtrate.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

a. Respiratory acidosis is caused by hypoventilation.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

b. Renal compensation for acid-base disturbances begins within minutes, whereas respiratory compensation begins within several hours.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

c. Respiratory compensation for metabolic acidosis consists of hypoventilation.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

d. Renal compensation for metabolic alkalosis consists of reabsorption of hydrogen ions and secretion of bicarbonate ions.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

e. You would expect to find an elevated Pco₂ in arterial blood gas analysis of a patient with respiratory acidosis.

Diabetic ketoacidosis is characterized by an increased level of ketone bodies, which causes metabolic acidosis. A patient in diabetic ketoacidosis will have an altered rate of ventilation. Will the patient be hyperventilating or hypoventilating? How will a change in the rate and depth of ventilation compensate for an acidosis that is metabolic in nature?

Elise Anderson is a 6-year-old girl who presents to the emergency department with a history of vomiting for the past 3 days. The nurse notices that her respiratory rate is abnormally low. What is the likely reason for this change in ventilation? Predict what Elise's arterial blood gas values would show.

Ms. Johanssen is a patient in the hospital. The nurse examines her laboratory reports and notices that she has developed hyperkalemia and acidosis over the past several days. On closer examination of her medical chart, the nurse also sees that her physician recently doubled her dose of spironolactone, an aldosterone-blocking diuretic. How does this explain her laboratory findings?

A laboratory printout of arterial blood gases indicates that a patient has an increased Pco₂ , decreased pH, and normal bicarbonate ion concentration. Is this patient in acidosis or alkalosis? Is the pH disturbance respiratory or metabolic in nature? Explain your reasoning. How long do you think the patient has had this pH disturbance? (Hint: Look at the bicarbonate ion concentration. What system controls the concentration of bicarbonate ions, and how quickly does it compensate for pH disturbances?)