Urine 5L

A set of Q&A flashcards covering thirst regulation, electrolyte imbalances, renin-angiotensin-aldosterone system, and acid-base balance (vomiting/diarrhea effects and compensations).

What activates the thirst center in the brain?

Low blood volume/pressure → Renin → Angiotensin II → Thirst center;

High blood osmolarity → Hypothalamus detects → ADH release → Thirst;

Dry mouth → Oral receptors trigger thirst sensation.

What deactivates the thirst center?

Increased blood volume/pressure → Less renin → Less angiotensin II → Less thirst; Distended stomach also helps reduce thirst.

What is hypernatremia and hyponatremia?

Hypernatremia = high blood sodium; Hyponatremia = low blood sodium.

What is hyperkalemia and hypokalemia?

Hyperkalemia = high blood potassium; Hypokalemia = low blood potassium.

What is hypercalcemia and hypocalcemia?

Hypercalcemia = less muscle/nervous excitability; Hypocalcemia = increased excitability (can cause spasms or breathing issues).

What is the role of renin-angiotensin in blood pressure regulation?

Renin forms angiotensin II, which causes vasoconstriction, reduces urine output, stimulates thirst, and triggers ADH and aldosterone release; All raise blood volume/pressure; Negative feedback shuts it off when BP is normal.

What does aldosterone do to regulate blood pressure?

Increases Na+ and water reabsorption → raises blood volume/pressure; Increases K+ excretion; Does not affect osmolarity (water and Na+ reabsorbed equally); Release stops via negative feedback once balance is restored.

How does vomiting affect blood hydrogen concentration?

Loss of HCl → decreased H+ in blood → metabolic alkalosis;

Compensation: reduced respiration to retain CO2; kidneys excrete bicarbonate if prolonged.

How does diarrhea affect blood hydrogen concentration?

Loss of bicarbonate (HCO3−) → less buffering → increased H+ → metabolic acidosis;

Compensation: increased respiration to blow off CO2; kidneys retain HCO3− and excrete H+.

What is respiratory acidosis and how is it corrected?

Caused by CO2 buildup (e.g., hypoventilation);

Compensation: kidneys reabsorb more HCO3− and secrete more H+; Slow compensation over hours–days.

What is metabolic acidosis and how is it corrected?

Caused by excess acid or loss of bicarbonate (e.g., DKA, diarrhea);

Compensation: kidneys excrete H+, reabsorb/generate more HCO3−; Use NH4+ and titratable acids to safely excrete H+.