Lecture 11- Acid-base balance; Calcium Flashcards
pH values that cannot sustain life
less than 6.8
more than 7.8
2 forms of acids
volatile and nonvolatile
… acids are by-products of metabolism that can be exhaled or dissipated by the lungs
volatile
CO2 is one beacuse it produces H+ in the water of body fluids
…. acids arise from metabolism or the diet; examples are phosphoric, lactic, sulfuric acids and ketones
nonvolatile
nonvolatile acids must be neutralized by… and are regulated by the … system.
HCO3
renal
**neutralization requires continual replenishment of HCO3
the lowest possible pH for urine is …. which represents very little free H+ and this pH is of the urine is not sufficient to excrete the nonvolatile acid load. therefore the kidney needs to excrete more acid than can be hel in a solution of this pH–> solution is buffers
4.4
physiological buffers?
bicarbonate
phosphate
hgb
plasma proteins
in addition to bicarbonate, the kidney uses … and … as buffers
phosphate (used 1st but supply is limited)
ammonium
Net acid excretion (NAE) should remove all … acid in 3 components
nonvolatile
H+, HPO4-2, NH4+
urine contains both titratable acids and …
NH4+
what are the titratable acids in the urine?
H+
HPO4-
kidney regulates acidity of the urine by regulating…. reabsorption
HCO3-
3 options for renal regulation of body pH
- decrease body pH by not reabsorbing all bicarb
- no effect by reabsorbing all bicarb
- increase body pH by reabsorbing all bicarb and making more bicarb
bicarb reabsorption begins in the … and …% of filtered bicarb is reabsorbed here
proximal tubule
80%
… = bicarb reabsorption
hydrogen secretion
T/F bicarb is directly transported from tubular fluid into blood
false
in the proximal tubule, … acitivity in the tubular epithelium produces … and …
… is secreted via … antiporter and … is reabsorbed across basolateral membrane
carbonic anhydrase
H+
HCO3-
H+
Na+/H+
HCO3-
T/F no bicarb is reabsorbed in the thick ascending limb
false. some is and it is in the same manner as the proximal tubule
production of NH4+ in the proximal tubules by metabolism of …
the NH4+ that is produced is transported into the tubular fluid and the HCO3- moves into the blood
glutamine
production of NH4+ in the proximal tubule cells is regulated by …
systemic pH
acidosis upregulates synthesis of enzymes for … metabolism but this takes time
glutamine
more NH4+ can be added to urine by …
diffusion trapping
much of the NH4+ leaving the proximal tubules is reabsorbed by the ….
NH4+ substitutes for K+ in the …. symporter and enters the interstitial fluid in the medulla where it is in equilibrium with NH3
ascending loop of henle
Na/K/2Cl
because NH4+ is a polar molecule then it is … in the interstitial fluid but NH3 being …. can diffuse into the lumen of the collecting ducts
because there is excess H+ on the fluid, NH3 in lumen is …. to NH4+ and is once again … and gets eliminated in urine
“trapped”
nonpolar
protonated
“trapped”
new bicarb can be produced in the …. by production of NH4+ from …
proximal tubule
glutamine
diarrhea will cause gain or loss of H+?
gain H+ because bicarb lost
vomiting will cause gain or loss of H+?
loss
distribution of calcium
ICF
ECF
bone
1%
0.1%
99%
how much of the calcium is free to be filtered?
about 1/2 of the 0.1% that is in the ECF
hypocalcemia increases … of neural and mucle tissue ; tetany
excitability
hypercalcemia can cause… and disorientation; can lead to death
cardiac arrythmias
calcium is regulated by these 3 hormones
parathyroid hormone (PTH)
calcitriol (1,25 dihydroxyvitamin D)
calcitonin
calcium is regulated by 3 hormones all of which are regulated by a…. found in plasma membrane of clls in parathyroid gland, thyroid parafollicular cells and cells of the proximal tubule
calcium sensing receptor (CaSR)
… is released in response to hypocalcemia. it increases bone resorption, increases renal calcium reabsorption and stimulates calcitriol production
parathyroid hormone (PTH)
… is released in response to hypercalcemia and increases bone deposition
calcitonin
… stimulates actice transport of calcium into the small intestine
calcitriol (1,25 dihydroxyvitamin D)
metabolism of vitamin D to calcitriol is stimulated by … and/or …
hypocalcemia
hypophosphatemia
… facilitates PTH and increases renal reabsorption of calcium
calcitriol
70% of calcium us reabsorbed in the proximal tubules mostly via …
paracellular transport (solvent drag)
in the thick ascending limb, calcium is reabsorbed via…
transcellular and paracellular transport (not solvent drag)
in the distal tubule, there is …. transport reabsorption of calcium and it can be regulated because expression of calcium transporters is regulated by ….
PTH
T/F the collecting ducts have a significant role in calcium reabsorption
false
