Acid/Base Flashcards
Acidosis has what effect on the CNS?
neurons
become less excitable and CNS depression results
Alkalosis has what effect on the CNS?
neurons
become hyperexcitable, firing action potentials at the slightest
signal leading to numbness or tingling, then as muscle twitches (tetanus)
Example of buffers in the ECF
HCO3 (bicarb)
Example of buffers in cells
Proteins, hemoglobin and phosphate
Examples of buffers in the urine
phosphates
Examples of H+ compounds from the diet and metabolism
Diet: Fatty acids, Amino acids
Metabolism: CO2, lactic acid, ketoacids
What is the most acidic urine kidneys can excrete
a pH of 4 to 4.5
How does H+ secretion aid in the reabsorption of HCO3
when H+ is secreted, it combines with filtered HCO3 in the renal tubule and forms CO2 which then diffuses into the renal tubule cells then is converted to H= and HCO3 through carbonic anhydrase
Primary factors/ compounds that cause increased secretion of H+
Decrease in ECF [HCO3-] (↓pH)
Increase in arterial PCO2
Cortisol
Endothelin
Secondary factors/ compounds that cause increased secretion of H+
Increase in the filtered load of HCO3-
ECF volume contraction
Angiotensin II
Aldosterone
Hypokalemia
PTH (chronic)
Primary factors/ compounds that cause decreased secretion of H+
Increase in ECF [HCO3-] (↑pH)
Decrease in arterial PCO2
Secondary factors/ compounds that cause decreased secretion of H+
Decrease in the filtered load of HCO3-
ECF volume expansion
Hypoaldosteronism
Hyperkalemia
PTH (acute)
Which amino acid is metabolized to form NH3 inside renal tubular cells
Glutamine
Alpha ketoglutarate is a metabolic by product from glutamine that will form which compound to be reabsorbed
HCO3 (bicarb)
How would hyperkalemia cause a decrease in H+ secretion
When there is a higher concentration of K+ in the the blood there will be less reabsorption of K+, there less K+ available for the K+/H+ transporter resulting in a decrease in H+ secreted
Which cells are responsible for H+ secretion during acidosis
Type A intercalated cells
Which cells are responsible for HCO3 secretion during alkalosis
Type B intercalated cells
During acidosis which transporters are activated and which one is inactivated
H+, K+-ATPase is activated and Na+,K+-ATPase is
inhibited
During acidosis, RAAS system is activated to release aldosterone.
How does this help?
Aldosterone will cause an upregulation of K+ channels and reactivation of Na+/K+ channels which allows more K+ to leave the cells and more HCO3 to be reabsorbed (cotransport with Na)
Which portion of the nephron reabsorbs most filtered bicarbonate and produces & secretes ammonium
proximal tubule
Which portion of the nephron reabsorbs second largest fraction of filtered bicarbonate
thick ascending limb
Which portion of the nephron:
Reabsorbs virtually all remaining filtered bicarbonate as well as any
secreted bicarbonate
Produces titratable acid
Secretes bicarbonate
Distal convoluted tubule and collecting duct system
How is a new bicarb molecule reabsorbed for every NH4 excreted
NH4 is made when glutamine metabolizes into NH3 and HCO3, the bicrb gets reabsorbed and the NH3 combines with H+ to make NH4
