Acid/base Flashcards
whats the most important extracellular buffer system
HCO3-
what do buffer systems include
proteins
phosphate ions
HCO3-
what senses plasma PCO2 and signals to the respiratory control centre
peripheral and central chemoreceptors
hyperventilation shifts what direction
left shift
what compensates for pH disturbances
ventilation
how much of the pH disturbances is handled by the kidneys
25%
how much of the pH disturbances is handled by ventilation
75%
what are the two mechanisms used by the kidneys to handle pH disturbances
directly
indirectly
what is “directly” mechanism
kidneys altering the rates of excretion or reabsorption of H+
what’d the “indirectly” mechanism
changing the rate at which HCO3- buffer is reabsorbed or secreted
what happens to excess H+ during acidosis
it is buffered by ammonia within tubule cells
or within the lumen by phosphate ions
is H+ filtered?
no
how does H+ enter the tubule
via secretion
what is H+ buffered in urine by
ammonia and phosphate ions
the proximal tubule secretes _____ and reabsorbs ________
H+
HCO3-
is HCO3- filtered
yes
how does HCO3- get into the cells in proximal tubules
converted to HCO3- in the cell but gets in by water and CO2 and carbonic anhydrase enzyme
are there HCO3- transporters on apical membrane of proximal tubule cells
no
what happens during acidosis (molecules)
start secreting hydrogen and reabsorb bicarbonate
where is there lots of carbonic anhydrase
the apical membrane
proximal tubule cells like to use an amino acid known as to produce energy.
glutamine
where does fine tuning happen
the distal nephron (collecting duct)
what cells are responsible for acid base balance within the collecting duct
intercalated cells
what cells are involved in fine regulation of acidosis
type A intercalated cells
