Lecture 3 Renal Flashcards
(57 cards)
normal pH range of body fluids and concentration of HCO3
7.35-7.45
HCO3= 24 mM
if pH 7.8 life can not be sustained
the greatest concern of the body is too much acid or base?
TOO MUCH ACID. body produces more acid than base
what are volatile acids
volatile acids are by products of metabolism that can be exhaled or dissipated by lungs Ex: CO2 bc it produces H in water of body fluids
What are nonvolatile acids
non volatile acids arise from metabolism or the diet Ex: phosphoric, lactic, and sulfuric acid and KETONES
how does body handle non volatile acid
neutralizes them with HCO3, regulated by renal system
theory says amount of acid in urine should equal the NonVolatile load how is this accomplish
the kidney does this by reabsorbing all filtered bicarbonate and then producing enough bicarbonate to neutralize acids produced by body
what is the lowest pH of urine possible? and what does this tell us
lowest urine pH can be is 4.4 so body has to excrete more acid than can be held in a solution of pH = 4.4
how does kidney excrete more acid than a pH of 4.4 will allow?
BUFFERING!
buffers bind to excess or free H to INC acid carried in urine without decreasing the pH
what molecules serve as buffers
HCO3, phosphate and ammonium
phosphate as a buffer
phosphate is used first but small supply
ammonium as a buffer
ammonium produced within tubular cells eliminates H and produces HCO3 that is reabsorbed
Net acid excretion should remove all non volatile acids what forms are secreted
free H
HPO4(-2)
and NH4
what two acids are titratable and what 1 acid is NOT Titratable
H and HPO4 (-2) ARE TITRATABLE
NH4 is NOT titratable
URINE has all 3!
under normal conditions what does the kidney do t regulate the acidity of urine
regulates HCO3 reabsorption by excreting acid equal to the non volatile load and replenishing the HCO3 lost to the neutralization of the acids
what are the 3 options for renal regulation of body pH that will produce an alkaline urine and acidifies body fluids
- DEC body pH by not reabsorbing HCO3 this urine is alkaline and body fluids acidic
- no effect on body pH by reabsorbing all HCO3, urine is neutral
- INC body pH by reabsorbing all and producing more HCO3, produces and acidic urine and basic body fluids
what happens due to the fact that HCO is NOT directly transported from tubular fluid into blood
HCO3 production and reabsorption results in H secretion`
what produces H and HCO in the tubular epithelium
Carbonic Anhydrase activity
How is H secreted after production by CA
H is secreted via Na H antiporter and via H ATPase pump and H/K ATPase pump which secretes H
how is HCO3 reabsorbed
HCO3 is reabsorbed/ transported across basolaterial membrane
Where does CA activity take place to produce H and HCO3
CA = late distal tubule and Collecting duct
what do intercalated cells doe in the late distal tubule and collecting ducts
reverses H and HCO3 transporters to the basolateral and apical membranes, THUS causing reabsorption of H and secretion of HCO3
VEYR LOW activity usually
if body is alkaline what must kidney do
produce alkaline urine by INC excretion of HCO3 and not neutralizing all the HCO3 in the tubular fluid
What do cells in the proximal tubule do regarding pH
PCT detects intracellular pH and can alter CA activity
when does kidney use phosphatase as an additional buffer
when body is acidic so it can INC excretion of H
