lecture 19 (T3): renal acid-base regulation Flashcards
which buffer system is most important in buffering renal tubular fluid
phosphate buffer system
compounds that dissociate incompletely into hydrogen ions and a conjugate base are members of what compound
weak acids
bicarbonate buffer system consists of ____ and _____
bicarbonate salt and weak acid
what occurs when there is a decrease in bicarbonate ion results in a decrease in the ratio of bicarbonate ion to carbon dioxide in the extra cell fluid
metabolic acidosis
what is respiratory alkalosis due to a decrease in carbon dioxide concentration caused by hyperventilation compensated by
renal excretion of bicarbonate ion
where does primary active hydrogen secretion involving a hydrogen-transporting ATPase occur
late distal tubule in intercalated cells
where does most bicarbonate reabsorption occur
proximal tubule
where is volatile acid excreted from
lungs
where is nonvolatile acids excreted form
kidneys
what are some major systems regulated H+ concentration
chemical acid-base buffer systems of the body fluids
respiratory center
kidneys
define buffer
substance that can reversibly bind H+
what does addition of a strong acid lead to in the bicarbonate buffer system
formation of a weak acid
what does addition of a strong base to the bicarbonate buffer system lead to
formation of weak base
what excretes the increases levels of HCO30 in the bicarbonate buffer system
kidneys
what do decreased CO2 levels in the bicarbonate buffer system do to respiration rate
decreases it
what is bicarbonate concentration regulated primarily by in the bicarbonate buffer system
kidneys
what is the pCO2 controlled by in the bicarbonate buffer system
rate of respiration
what is the most important extracellular buffer system
bicarbonate buffer system
what do metabolic acid base disorders primarily result form
change in bicarbonate concentrations in extracellular fluid
what does respiratory acid base disorders primarily result from
change in pCO2
why is phosphate buffer system important
plays major role in buffering tubular fluid and intracellular fluids
why is the phosphate buffer system important in the kidneys (2 reasons)
usually becomes greatly concentrated in the tubules
lower pH of the tubular fluid brings the operating range of the buffer closer to the pk of the buffer system
what is the primary method for removing nonvolatile acids
through renal excretion
what are mechanisms for regulating extracellular H+
kidneys reabsorb filtered extracellular H+
kidneys can secrete hydrogen ions
kidneys produce new bicarbonate ions
where does hydrogen ion secretion via secondary transport occur
almost all parts of the tubules except descending and ascending thin limbs of the loop of henle
where does bring active hydrogen secretion begin
in the late distal tubules in intercalated cells and involves a hydrogen-transporting ATPase
where does the majority of bicarbonate reabsorption occur
proximal tubule
why is carbonic anhydrase necessary
it is necessary for the formation of carbonic acid from carbon dioxide and water
how is incomplete titration used to correct acidosis
in metabolic acidosis, new bicarbonate ion is added to the extracellular fluid
how is incomplete titration used to correct alkalosis
in metabolic alkalosis, bicarbonate ions are removed form the extracellular fluid by renal excretion
how does the tubular epithelium secretion hydrogen ion
via primary active transport
what is active transport resulting in hydrogen ion secretion carried out by
intercalated cells
how does hydrogen ion secretion in the proximal tubule occur
via secondary sodium-hydrogen counter-transport
where are the sodium-hydrogen exchanges located
on the apical (luminal) membranes of the renal epithelial cells
where are sodium-potassium-ATPase exchangers found
basal membranes
what is the lower limit of pH that can be achieved in normal cells
4.5
how are nonvolatile acids primarily removed
via renal excretion
what is the minimal urine pH
4.5
how are excess hydrogen ions eliminated
through binding with phosphate or ammonia ions
how do the kidneys correct alkalosis
failing to reabsorb all the filtered bicarbonate ions or adding hydrogen ion to the extracellular fluid
what happens when there is a decreases in the ration of bicarbonate ion to carbon dioxide in extracellular fluid
decrease in bicarbonate ion: metabolic acidosis
increase in CO2: respiratory acidosis
what is the primarily compensatory response to respiratory acidosis
increase in plasma bicarbonate ion due to addition of new bicarbonate by the kidney
what is the primary compensatory response to metabolic acidosis
increase in ventilation rate
what is the renal compensation to metabolic acidosis
adds new bicarbonate ion to extracellular fluid
in alkalosis, how is excess bicarbonate excreted
in urine
what is respiratory alkalosis caused by
hyperventilation
what is the compensatory response to respiratory alkalosis
reduction in plasma bicarbonate ion concentration caused by renal excretion of bicarbonate ion
what is metabolic alkalosis caused by
rise in the extracellular fluid bicarbonate ion concentration
what is the compensatory response to metabolic alkalosis
decreased ventilation
increased renal bicarbonate ion excretion
