Ch. 37: Water, Electrolytes, Acid-Base Balance Flashcards
3 main functions of the kidneys?
1) form protein-free ultrafiltrate @ glomerulus
2) active resorption of solute from filtrate
3) active excretion (e.g. H+) into lumen
What is normal GFR?
100-120 mL/min
Osmolarity of extra cellular fluid (due to Na+ & anions) is kept w/in narrow range, via what processes?
1) water intake (thirst center)
2) water excretion (ADH)
What is the antagonistic system to RAAS? (to ⬇️ blood volume)
High blood volume ➡️ cardiocytes release ANP ➡️ diuresis & natriuresis (via ⬆️ GFR & inhibit Na+ reabsorption)
Antagonistic system to RAAS: MoA?
ANP binds to plasma membrane receptor ➡️ form cGMP ➡️ activate cGMP dependent protein kinases
What hormone has similar structure to ADH & is also made by posterior pituitary ➡️ can co-inact with ADH?
Oxytocin
What is osmolality? How is it measured?
particles per unit wt of solvent
Freezing point or vapor pressure depression
Diabetes insipidus vs Diabetes mellitus?
DI: problem with ADH secretion or ADH receptors/aquaporins ➡️ bland urine
DM: problem with glucose regulation ➡️ sweet urine
What promotes K+ uptake into cells?
What promotes K+ excretion into urine?
Insulin, catecholamines
Aldosterone
What is the most important buffer in the body? What regulates it?
Carbonic acid-bicarbonate system
Kidneys (slower) & respiration (faster)
What are the 3 ways the kidneys actively secrete H+ ?
1) Na+ / H + exchange
2) Reclaim bicarbonate
3) Production of ammonia & excretion of NH4+
Where is carbonic anhydrase I found?
Blood (RBCs)
Where is carbonic anhydrase II found?
Bone, kidneys (in PCT cell)
Where is carbonic anhydrase III found?
Skeletal muscle
Where is carbonic anhydrase IV found?
Kidney (PCT lumen)
How does ammonia production by kidneys cause secrete H+ ?
Ammonia (hydrophobic) ➡️ freely crosses into lumen ➡️ combines w/H+ to form ammonium ion (not hydrophobic) ➡️ ammonium ion trapped in lumen, excreted in urine
Equation to calculate anion gap?
Normal anion gap?
Anion gap = [Na+] + [K+] - [Cl-] - [HCO3-]
12 +/- 4 mEq/L (positive gap due to high Na+ in blood)
What does high anion gap indicate?
Indicates very high Na+ ➡️ something else (another anion) is countering Na+
What indicates metabolic acidosis? How does body react?
pH <7.4 due to ⬇️ [HCO3-]
Respiratory compensation (⬇️ Pco2)
What indicates respiratory acidosis? How does body react?
pH <7.4 due to ⬆️ Pco2
Renal compensation (⬆️ HCO3-)
What indicates metabolic alkalosis? How does body react?
pH > 7.40 due to ⬆️ [HCO3-]
Respiratory compensation (⬆️ Pco2)
What indicates respiratory alkalosis? How does body react?
pH > 7.40 due to ⬇️ Pco2
Renal compensation (⬇️ HCO3-)
What are the 3 ketone bodies? Which 2 are acidic?
Acetoacetate (acidic)
Hydroxybutyrate (acidic)
Acetone
