Lecture 19: Acid/Base Regulation Flashcards
What is a buffer?
Substance that can reversibly bind H+ (contains a weak acid)
What are the 3 main buffer systems of the body and which is the most important extracellular buffer system?
Bicarbonate, Phosphate, and Proteins
*Bicarbonate most important
How is the bicarbonate buffer system regulated?
By the kidneys, which excrete excess HCO3-
Metabolic Acid-Base disorders
Due to change in extracellular [HCO3-]
Alkalosis: high [HCO3-]
Acidosis: low [HCO3-]
Respiratory Acid-Base disorders
Due to change in pCO2
Acidosis: high pCO2
Alkalosis: low pCO2
Why is the phosphate buffer system conducive to working in the renal tubular fluid?
Low pH of tubular fluid is optimal operating range because buffer is close to pK of the system
Where are intercalated cells found?
Late distal renal tubules
How does excess H+ secretion form new HCO3-?
H+ binds with buffers so that excess HCO3- can be returned to the blood as “new” bicarbonate ion
How do the kidneys handle excess base/alkalosis?
Fail to reabsorb all filtered bicarbonate ion, lowering the pH
What is metabolic acidosis and what is the compensatory response?
Decrease in HCO3-
*Compensatory: lungs increase ventilation rate (kidneys can also add more HCO3- to EC fluid)
What is respiratory acidosis and what is the compensatory response?
Increase in CO2
*Compensatory: kidneys produce more HCO3-
What is metabolic alkalosis and what is the compensatory response?
Increase in HCO3-
*Compensatory: decreased ventilation in lungs (less CO2 blown off), kidneys can also excrete HCO3-
What is respiratory alkalosis and what is the compensatory response?
Decrease in CO2
*Compensatory: renal excretion of HCO3-
Which of the following buffer systems is most important in buffering renal tubular fluid?
A. Phosphate buffer system
B. Carbonate buffer system
C. Bicarbonate buffer system
D. Hemoglobin buffer system
A. Phosphate buffer system
Compounds that disassociate incompletely into hydrogen ions and a conjugate base are members of which of the following compounds?
A. Strong acids
B. Weak acids
C. Strong bases
D. Weak bases
B. Weak acids
The bicarbonate buffer system consists of a bicarbonate salt and which of the following?
A. Weak acid
B. Strong acid
C. Weak base
D. Strong base
A. Weak acids
Which of the following buffer systems is the most important buffer system?
A. Phosphate buffer system
B. Carbonate buffer system
C. Bicarbonate buffer system
D. Hemoglobin buffer system
C. Bicarbonate buffer system
Primary active hydrogen secretion involves a hydrogen transporting ATPase. It occurs in which of the following parts of the renal tubules?
A. Descending limb of Henle
B. Ascending limb of Henle
C. Late distal tubules in intercalated cells
D. Early collecting tubules in principal cells
C. Late distal tubules in intercalated cells
Most bicarbonate reabsorption occurs in which of the following parts of the renal tubule?
A. Proximal tubule
B. Descending limb of Henle
C. Ascending limb of Henle
D. Distal tubule
A. Proximal tubule
Which of the following occurs when a decrease in bicarbonate ion results in a decrease in the ratio of bicarbonate ion to carbon dioxide in the extracellular fluid?
A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis
C. Metabolic acidosis
Respiratory alkalosis due to a decrease in CO2 concentration caused by hyperventilation is compensated for by which of the following mechanisms?
A. Increased ventilation rate
B. Decreased ventilation rate
C. Renal excretion of bicarbonate ion
D. Renal addition of new bicarbonate ion to extracellular fluid
C. Renal excretion of bicarbonate ion
