MLT GlobePhysiology: Renal physiology & acid-base – page 2
29 Physiology MCQs on Renal physiology & acid-base with answers and explanations.
A patient with a bladder infection is most likely to report which symptom?
Cystitis (bladder inflammation) causes frequency, urgency and dysuria; it is commoner in women and can be non-infective. Renal pelvis inflammation is pyelonephritis.
A dehydrated person secretes ADH and passes concentrated urine. At the cellular level, ADH achieves this by:
ADH binds V2 receptors and moves aquaporin-2 into the luminal membrane of collecting-duct cells, making them permeable to water so urine becomes concentrated.
Movement of H+ and K+ from peritubular capillary blood into the tubular fluid is termed:
Urine forms by filtration, reabsorption and secretion. Secretion adds substances such as H+, K+ and some drugs from blood into the tubule; reabsorption moves substances the opposite way.
With a GFR of about 125 mL/min, roughly how much filtrate do the kidneys form in 24 hours?
125 mL/min x 1440 min is about 180 L/day. Over 99% is reabsorbed, leaving about 1.5 L of urine.
The maximum capacity of the adult urinary bladder is approximately:
The adult bladder can hold roughly 500-600 mL, although the urge to void is usually felt at about 300-400 mL.
At roughly what bladder volume does an adult usually first become aware of the need to pass urine?
Stretch receptors in the bladder wall signal a desire to void at about 300-400 mL; micturition can usually be postponed until nearer maximum capacity.
Which organ does NOT contribute a key component to the renin–angiotensin–aldosterone pathway?
The liver makes angiotensinogen, the kidney releases renin, and pulmonary endothelium supplies most ACE; the adrenal cortex makes aldosterone. The heart releases natriuretic peptides that oppose this system.
Which condition lowers GFR by raising hydrostatic pressure in Bowman's capsule?
Urinary obstruction raises back-pressure in the tubule and Bowman's space, opposing filtration. Afferent dilation, efferent constriction and low oncotic pressure all tend to increase GFR.
Why is glomerular capillary pressure much higher than in most other capillary beds?
Blood leaves the glomerulus through a narrower, high-resistance efferent arteriole, keeping glomerular hydrostatic pressure near 55-60 mmHg and driving filtration along the whole capillary.