renal 3 Flashcards
what is the normal pH range for the human body
7.35-745
what is the nornmal HCO3 concentration of the body
24mM
outside of what pH can life not be sustained
less than 6.8
greater than 7.8
is it worse to be too basic or too acidic
too acidic, because body takes in more acid than base
what are the two forms of acid in the body
Volatile acids
Nonvolatile acids
what is a volatile acid
By-products of metabolism to be exhaled or dissipated by the lungs
what is CO2 an acid
produces H in the water of body fluids
what are nonvolatile acids
arise from metabolism of the diet
what are examples of nonvolatile acids
Phosphoric acid
Lactic
Sulfuric acids
Ketones
how can nonvolatile acids be neutralized
with HCO
what regulates nonvolatile acids
REnal system
what does neutralization of nonvolatile acids need
continual replenishment of HCO3
how much acid should be found in the urin
the same as the nonvolatile acid load
how does the kidney help in assuring that the amount of acid in the urine is equal to the nonvolatile acid load
reabsorbing all the filtered bicarbonate, then producing enough new bicarb to neutralize acids produced by the body
what is the lowest possible pH for urine
4.4
why is the lowest possible pH for urine 4.4
little free H, so not suffieicnet to excrete the nonvolatile acid load
- kidney must excrete more acid than can be held in solution (solid acid)
what helps to ensure that the pH of urine never gets to low
Buffers binding to excess H to increase acid carried in urine without decreasing pH
what acts as physiological buffers
HCO3
Phosphate
Ammonia
- all increase the amount of H excred
what physiologic bugger is used first
Phosphate (endogenous)
what is the action of Ammonium to serve as a buffer
Eliminates H and produces HCO3 that is reabsorbed
where is ammonium produces
within tubular cells
what should removal all nonvolatile acid
Net acid excretion
what are the 3 forms in which nonvolatile acid is excreted
Free H
H2PO4
NH4
what are the titratable acids in urin
H and H2PO4 to a pH of 7.4
what is the pka of NH4
9 ( not titratable)
what does the kidney use to regulate the acidity of urine
regulate HCO3 reabsorption
how much HCO3 is replenished by the kidney in normal contions
- kidney excretes acid equal to the nonvolatile load
- replenishes the HCO3 due to neutralizing the nonvolatile acids
what are the options for renal regualtion of body pH that will produce urine with different pH
- decrease body pH by not reabsorbing all HCO3
- no effect on body pH by reabsorbing all HCO3
- increase body pH by reabsorbing all and prodcuing more HCO3
what does not reabsorbing all HCO3 do to the urine and body fluid
alkaline urine
acid body fluid
what does reabsorbing all HCO3 do to the urine and the body fluid
urine and pH is neutral
what does reabsorbing all and producing more HCO3 do to the urine and body fluid
acid urine
alkalinizes body fluid
what is the most commone way the kidney regulates body pH
increase body pH by reabsorbing all and producing more HCO3
why does the fact that HCO3 transport from tubular fluid into blood is not direct
HCO3 production and reabsorption results in H secretion
where does Bicarb reabsorption begin
80% done in the Proximal tubule
what in the tubular epithelial cells produces H and HCO3
CA cativity
how is H secreted in tubular eptihelial cells
via Na/H antiporter
- also H ATPase
- H/K ATPase pumps
what happens to the HCO3 that is is created via CA activity
transported/reabsorbed across basolateral membrane
appart from the proximal tubule, where is HCO3 reabsorbed
Thick ascending limb of the loop of hendle (similar to proximal tubule)
late distal tubule
how is HCO3 reabsorbed and H secreted in the LAte distal tubule
CA actvity produces H and HCO
- H secreted via H ATPase pumps and H/K ATPase pump
what happens to secreted H to control pH
buffered by HCO3, HPO4, ammonia
where is the last of all filtered HCO reabsorbed
Late distal tubule and collecting duct
what cells reabsorb HCO3 in the late distal tubule and collecting duct
Intercalated cells
how is HCO33 secreted and H reabsorbed
by a less common intercalated cell with reversed position of the H and HCO3 transporters
should urine be acidic or alkaline
Alkaline (since body is alkaline)
what does the kidney do to keep urine alkaline
Incomplete reabsorption of HCO3
- increase excretion of HCO3 by not neutralizing all the HCO3 that is in tubular fluid
how does the body control the creation of HCO3 to keep urine alkaline
cells of proximal tubule detect intracellular pH and alter CA activity
what does the body do if the body is acidic
Use phophate as an additional buffer to increase excretion of H
why does the body produce NH4
after all the HCO3 is reabsorbed and HPO4 is depleted, NH4 acts as a 3rd buffer to increase the amount of H excreted
is it alright if NH4 enters the body
No, its no good since it will be converted to urea and produce H as a result
where is Nh4 produced
In the proximal tubules
how is NH4 produces in the proximal tubules
metabolism of glutamine
how is NH4 transported into tubular fluid
using Na, NH4 antiporters as HCO3 moves into the blood
what regulates production of NH4 in the proximal tubule
systemic pH
- acidosis upregulates synth of enzymes for gluamine metabolism
does responding to acidosis with NH4 production occure quickly
No, takes time
how can more NH4 be added to the urine
diffusion trapping
where is much of the nH4 leaving the proximal tubule reabsorbed
ascending limb of the loop of henle
how does NH4 enter the interstial fluid in diffusion trappyin
NH4 substitutes K in the Na K 2Cl symporter in the medulla
what is NH4 in equilibrium with in the medulla for diffusion trapping
Eq with NH3
how does difusion trapping work
Once the charged NH4 is in the interstial fluid, it can’t go through the cells
-non polar NH3 can diffuse though into the lumen of nearly collecting ducks
how does diffusion trapping increase pH
when NH3 diffuses into the collecting duct, it is protonated into NH4 and then again is trapped and cannot get reabsorbed
what is respiratory acidosis
low pH due to CO2 build-up
what causes respiratory acidosis
Impaired pulmonary function
what is the renal compensatory response to respiratory acidosis
produce new HCO3
what is respiratory alkalosis
high pH due to low PCo2
causes of respiratory alkalosis
hyperventilation, anxiety, altitude, fever, drugs
what is the renal compensaory response to respiratory alkalosis
excrete HCO3
what is metabolic acidosis
Low pH due to low HCO3
causes of metabolic acidosis
diabetic ketosis, diarrhea, renal failure
what is the respiratory compensatory response to metabolic acidosis
Hyperventilate
what is the renal compensatory response to metabolic acidosis
produce new HCO3
what is metabolic alkalosis
high pH due to excess HCO3
causes of metabolic alkalosis
vomiting
Antacids
Hemorrhages
what is the respiratory compensatory response to metabolic alkalosis
hypoventilate
what is the renal compensatory response to metabolic alkalosis
excrete HCO3
where is the calcium found in the body
1% in the ICF
.1% of the ECF
99% in the bone
what state is 1/2 the ECF calcium in
is free or complexed with anions
why is it important the 1/2 of the ECF of calcium is free or complexed with anioins
can be filtered in the glomerulus
what is the importance of calcium and phosphae
Cellular processes
what organ systems regulate calcium
renal and digestive system to balance GI absorption and renal excretion
what are some problems with hypocalcemia
increased excitability of neural and muscle tissue (tetany)
what are some problems with hypercalcemia
cardiac arrhythmia and disorientation
- death
how does pH affect free calcium levels
- decrease plasma pH increases free calcium to filter and excrete
- increase plasma pH leads to less free calcium
what hormones regulate calcium
Parathyroid hormone (PTH)
Calcitriol (1,25 dihydroxyvitamin D)
Calcitonin
what regulates all the hormones that regulate calcium
Calcium sensing recptor
where is calcium sensing receptor found
plasma membrane of cells of the parathyroid gland, thyroid parafollicular cells, cells of the proximal tubule
what stimulates release of parathyroid hromone
Hypocalcaemia
what is the action of parathyroid hromone
bone resorption
increased renal Ca reabsorption
stimulate calcitriol production
what does calcitriol come from
MEtabolism of Vitamin D
what stimulates vit D metabolism to calcitriol
hypocalcaemia or hyophosphatemia (further stimulated from PTH)
what is the action of calcitriol
- stimulates active transport mechanism for Ca absorption in small intestine
- faciliates action of PTH and increases renal Ca transport
why is calcitonin release
respond to hypercalcaemia
what odes calcitonin do
increase bone deposiion
how is calcium reabsorbed in the nephron
paracellular transport/solvent drag
who si calcium reabsorbed in the thick ascending limb
transcullar and paracellular (no solvent drag in in paracellular)
where is calcium reabsoprtion regulates
transcellular regulated in distal tubule due to Ca transporters regulated by PTH
how does the collecting duct reabsorb calcium
does not reabsorb the calcium
