Renal 2 Flashcards
(19 cards)
What is the main function of the countercurrent multiplier system?
To create a hyperosmotic medullary interstitium for water reabsorption.
Which part of the nephron is impermeable to water?
The ascending limb of the loop of Henle.
Which part of the nephron is permeable to water but not NaCl?
The descending limb of the loop of Henle.
What is the role of ADH in the collecting duct?
It inserts aquaporins into the apical membrane, increasing water reabsorption.
What is the function of the vasa recta?
To preserve the osmotic gradient via countercurrent exchange.
What is the maximum urine osmolarity achievable by human kidneys?
Around 1200–1400 mOsm/L.
What stimulates ADH secretion?
Increased plasma osmolality and decreased blood volume or pressure.
Where is ADH synthesised and released?
Synthesised in the hypothalamus (SO and PVN nuclei), released by the posterior pituitary.
What inhibits ADH release?
Alcohol.
What factors enhance ADH secretion besides osmolality?
Pain, stress, exercise, nicotine, and Angiotensin II.
What is micturition?
The process of urination involving stretch receptor activation and spinal reflex.
Which muscle contracts during micturition?
The detrusor muscle.
Which muscles relax during micturition?
The internal and external urethral sphincters.
What is the normal blood pH range?
7.35 to 7.45.
What causes metabolic acidosis?
Loss of bicarbonate (e.g., diarrhoea) or accumulation of acids (e.g., ketoacidosis).
How do the kidneys compensate for metabolic acidosis?
By reabsorbing HCO3−, secreting H+, and generating new HCO3−.
What causes respiratory acidosis?
Hypoventilation leading to CO2 retention.
What causes respiratory alkalosis?
Hyperventilation leading to CO2 loss.
What is the role of glutamine metabolism in the kidney?
It produces ammonium and new bicarbonate during acidosis.
