front 1 A patient with high circulating ADH forms very concentrated urine because water leaves the collecting duct until tubular fluid equilibrates with which compartment? A) Renal cortex B) Renal medulla C) Peritubular plasma D) Bowman space | back 1 B. Renal medulla ADH opens water channels → water leaves collecting duct → follows salty medulla → concentrated urine |
front 2 A dehydrated patient has high ADH and high urea concentration in the medullary collecting duct. Which transporter pair most directly allows urea to leave this duct and enter the medullary interstitium? A) UT-A1 and UT-A2 B) UT-A2 and UT-B C) UT-B and AQP1 D) UT-A1 and UT-A3 | back 2 D. UT-A1 and UT-A3 medullary collecting duct lumen → UT-A1 → cell → UT-A3 → medullary interstitium |
front 3 A researcher is modeling urea handling by the kidney. Which combination best determines the final rate of urea excretion? A) Plasma urea, GFR, tubular reabsorption B) Plasma sodium, RPF, tubular secretion C) Medullary flow, ADH, distal potassium D) Cortical tonicity, aldosterone, sodium delivery | back 3 A. Plasma urea, GFR, tubular reabsorption Urea excretion = filtered urea − reabsorbed urea |
front 4 Urea recycling helps maintain the hyperosmotic renal medulla. Which transporter mediates passive urea movement from the medullary interstitium into the thin loops of Henle? A) UT-A1 B) UT-A3 C) UT-A2 D) AQP1 | back 4 C. UT-A2 |
front 5 A patient with high serum ADH has already increased water reabsorption in the distal nephron, leaving urea highly concentrated in tubular fluid. Which process then reinforces medullary hyperosmolarity? A) Urea exits through UT-A1/UT-A3 B) Sodium exits through UT-A2 C) Water exits through UT-B D) Urea exits through AQP1 | back 5 A. Urea exits through UT-A1/UT-A3 ADH → water leaves collecting duct → urea becomes concentrated → urea exits via UT-A1/UT-A3 → medulla becomes more salty/hyperosmotic → urine concentrates more |
front 6 As blood in the vasa recta ascends from the renal medulla toward the cortex, which exchange pattern best preserves the corticomedullary gradient? A) Solutes enter, water exits B) Solutes enter, water enters C) Solutes exit, water exits D) Solutes exit, water enters | back 6 D. Solutes exit, water enters descending vasa recta: gains solute, loses water |
front 7 The vasa recta are arranged as slow countercurrent exchangers. What is their key function in urine concentration? A) Create filtrate in Bowman space B) Prevent medullary gradient washout C) Secrete urea into distal tubules D) Pump sodium into cortex | back 7 B. Prevent medullary gradient washout |
front 8 A patient has increased medullary blood flow through the vasa recta. What effect would this most likely have on maximum urine-concentrating ability? A) Increase by trapping solute B) Increase by removing water C) Decrease by washing solute away D) Decrease by blocking ADH release | back 8 C. Decrease by washing solute away |
front 9 A nephron segment reabsorbs water rapidly and almost iso-osmotically with solute. Which channel mainly aids water diffusion across this proximal tubular epithelium? A) AQP2 B) UT-A1 C) UT-A2 D) AQP1 | back 9 D. AQP1 |
front 10 A tubular fluid sample is taken after passage through the thick ascending limb of the loop of Henle. What best describes its osmolarity relative to plasma? A) Very dilute B) Very concentrated C) Identical to medulla D) Protein-rich | back 10 A. Very dilute thick ascending limb → salt leaves → water cannot follow → tubular fluid becomes dilute |
front 11 High ADH increases water permeability before tubular fluid reaches the medullary collecting duct. Which nephron regions are directly made water-permeable in this setting? A) PCT and thin descending limb B) Macula densa and glomerulus C) Late distal and cortical collecting tubules D) Thick ascending and proximal tubules | back 11 C. Late distal and cortical collecting tubules High ADH makes the late distal tubule and cortical collecting tubule water-permeable by inserting aquaporin-2 channels. So before the fluid even reaches the medullary collecting duct, ADH has already pulled out a lot of water. |
front 12 A dehydrated patient has urine osmolarity greater than plasma osmolarity. What does this urine-plasma relationship indicate physiologically? A) Obligatory salt wasting B) Net water conservation C) Primary bicarbonate loss D) Excess water excretion | back 12 B. Net water conservation dehydration → ADH high → water reabsorbed → urine becomes concentrated → body conserves water |
front 13 A patient has polyuria and polydipsia due to deficient posterior pituitary ADH release. Which treatment-receptor-site pairing is most appropriate? A) Desmopressin, V2, distal/collecting tubules B) Desmopressin, V1, proximal tubules C) Vasopressin, V1, thick ascending limb D) Aldosterone, mineralocorticoid, collecting ducts | back 13 A. Desmopressin, V2, distal/collecting tubules |
front 14 A patient with suspected diabetes insipidus receives desmopressin, but urine osmolarity fails to increase. Which diagnosis best explains this response? A) Central diabetes insipidus B) Primary hyperaldosteronism C) SIADH D) Nephrogenic diabetes insipidus | back 14 D. Nephrogenic diabetes insipidus |
front 15 A water deprivation test shows low urine osmolarity that markedly increases after desmopressin administration. Which mechanism best explains this correction? A) Increased tubular sodium secretion B) V2-mediated water permeability increase C) UT-A2 blockade in thin limbs D) Reduced medullary interstitial tonicity | back 15 B. V2-mediated water permeability increase |
front 16 A patient with nephrogenic diabetes insipidus receives desmopressin. Why does urine osmolarity remain low despite the medication? A) Kidneys cannot respond to ADH B) Posterior pituitary cannot release ADH C) Plasma urea concentration is excessive D) Vasa recta blood flow stops | back 16 A. Kidneys cannot respond to ADH |
front 17 During high ADH states, urea contributes strongly to inner medullary hyperosmolarity. Which sequence best describes the relevant urea recycling pathway? A) Cortex to glomerulus via AQP1 B) Thick limb to cortex via UT-B C) Interstitium to thin limb via UT-A2 D) Distal tubule to PCT via V2 | back 17 C. Interstitium to thin limb via UT-A2 ADH ↑ → urea exits collecting duct → urea enters medullary interstitium → urea reenters thin limb via UT-A2 → urea cycles again |
front 18 A drug selectively blocks UT-A1 and UT-A3 in the medullary collecting duct. Which renal concentrating process would be most directly impaired? A) Proximal water diffusion B) Thick limb fluid dilution C) Urea entry into medulla D) V2 receptor activation | back 18 C. Urea entry into medulla |
front 19 Renal imaging shows cortical tissue extending between adjacent medullary pyramids. Which anatomic structure is being identified? A) Renal papilla B) Columns of Bertin C) Minor calyx D) Renal capsule | back 19 B. Columns of Bertin |
front 20 What best describes the loop of Henle as it goes deeper into the medulla? A) More hyperosmotic B) More hypoosmotic C) Protein impermeable D) Fully isoosmotic | back 20 A. More hyperosmotic That means the medulla is “saltier”/more concentrated than the cortex. |
front 21 The vasa recta run alongside loops of Henle and participate in countercurrent exchange. Besides preserving medullary tonicity, what essential exchange do they allow? A) Bile and bilirubin B) Glucose and lactate C) Oxygen and nutrients D) Albumin and fibrinogen | back 21 C. Oxygen and nutrients |
front 22 A patient’s bladder sympathetic pathway is traced from spinal cord to its peripheral synapse. Where do sympathetic fibers to the bladder synapse? A) Pelvic splanchnic nerves B) Hypogastric plexus C) Pudendal canal D) Vesical epithelium | back 22 B. Hypogastric plexus |
front 23 During normal micturition, parasympathetic output coordinates bladder emptying. Which paired muscular response best describes this effect? A) Detrusor contracts, internal sphincter relaxes B) Detrusor relaxes, internal sphincter contracts C) Detrusor contracts, external sphincter contracts D) Detrusor relaxes, external sphincter relaxes | back 23 A. Detrusor contracts, internal sphincter relaxes |
front 24 Which division primarily initiates erection? A) Sympathetic nervous system B) Somatic pudendal system C) Parasympathetic nervous system D) Enteric nervous system | back 24 C. Parasympathetic nervous system |
front 25 During ejaculation, semen is prevented from refluxing into the bladder. Which autonomic pathway closes the internal urethral sphincter? A) Parasympathetics S2-S4 B) Sympathetics L1-L2 C) Pudendal nerve S2-S4 D) Vagus nerve medulla | back 25 B. Sympathetics L1-L2 |
front 26 During ejaculation, contraction of urethral smooth muscle is attributed in these notes to which pathway? A) Sympathetics T5-T9 B) Pudendal motor fibers C) Hypogastric sensory fibers D) Parasympathetics S2-S4 | back 26 D. Parasympathetics S2-S4 |
front 27 A patient becomes dehydrated after prolonged sweating. Which serum change most directly stimulates ADH secretion? A) Increased serum osmolarity B) Decreased serum osmolarity C) Increased urine sodium D) Decreased urine urea | back 27 A. Increased serum osmolarity |
front 28 The kidney can excrete water while conserving solutes, producing dilute urine. Which nephron regions are stimulated to reabsorb solutes during this process? A) PCT and descending limb B) Thin limb and macula densa C) Glomerulus and Bowman space D) Late distal tubule and collecting ducts | back 28 D. Late distal tubule and collecting ducts |
front 29 A sample is taken from the proximal tubule. How does tubular fluid compare with serum here? A) Strongly hypoosmotic B) Strongly hyperosmotic C) Mostly isoosmotic D) Protein enriched | back 29 C. Mostly isoosmotic proximal tubule → Na⁺ and other solutes reabsorbed → water follows → tubular fluid stays about isoosmotic with serum |
front 30 As filtrate passes through the descending loop of Henle, it equilibrates with the surrounding renal medulla. Which transport event explains this concentration change? A) Water is reabsorbed B) Sodium is secreted C) Urea is destroyed D) Potassium is secreted | back 30 A. Water is reabsorbed |
front 31 A tubular fluid sample becomes progressively more concentrated while descending into the medulla. What is the best explanation? A) NaCl secretion into lumen B) Water reabsorption into medulla C) Protein filtration increases distally D) ADH blocks water permeability | back 31 B. Water reabsorption into medulla |
front 32 In the ascending limb of the loop of Henle, filtrate becomes diluted because the segment actively reabsorbs which solutes? A) Urea and glucose B) Albumin and calcium C) Bicarbonate and phosphate D) Na+, K+, and ions | back 32 D. Na+, K+, and ions |
front 33 A nephron segment actively removes ions but is relatively water impermeable. Which segment is best described? A) Ascending loop of Henle B) Descending loop of Henle C) Proximal convoluted tubule D) Medullary collecting duct | back 33 A. Ascending loop of Henle |
front 34 Regardless of ADH level, tubular fluid leaving the early distal tubule has which osmotic property? A) Hyperosmotic to plasma B) Hypoosmotic to plasma C) Isoosmotic to plasma D) Equal to medulla | back 34 B. Hypoosmotic to plasma The early distal tubule is part of the diluting segment. Before this, the thick ascending limb has removed Na⁺, K⁺, and Cl⁻, but water could not follow. So the fluid entering/leaving the early distal tubule is dilute. |
front 35 A patient lacks ADH activity. What happens to fluid in the distal and collecting tubules? A) It becomes more dilute B) It becomes protein rich C) It equilibrates with medulla D) It becomes more acidic | back 35 A. It becomes more dilute |
front 36 In the absence of ADH, why does tubular fluid become more dilute in the distal nephron and collecting ducts? A) Urea replaces sodium reabsorption B) Water permeability remains low C) Plasma osmolarity rapidly decreases D) Vasa recta blood flow stops | back 36 B. Water permeability remains low |
front 37 A 70-kg patient must excrete 600 mOsm of solute daily and can maximally concentrate urine to 1200 mOsm/L. What obligatory urine volume is required? A) 0.25 L/day B) 0.5 L/day C) 1.0 L/day D) 2.0 L/day | back 37 B. 0.5 L/day |
front 38 A laboratory wants to estimate urine specific gravity from a patient’s urine sample. Which instrument is commonly used? A) Refractometer B) Hemocytometer C) Spectrophotometer D) Flow cytometer | back 38 A. Refractometer |
front 39 A dehydrated patient has high ADH and a very hyperosmotic renal medulla. What movement directly allows water conservation? A) Water enters collecting ducts B) Water exits into medullary interstitium C) Sodium enters collecting ducts D) Urea exits through glomerulus | back 39 B. Water exits into medullary interstitium ADH ↑ → collecting duct water permeability ↑ → water exits tubule → water returns to blood → urine becomes concentrated |
front 40 In high ADH states, water leaves the collecting duct into the medullary interstitium and is ultimately returned to circulation through which structure? A) Bowman capsule B) Minor calyx C) Vasa recta D) Renal pelvis | back 40 C. Vasa recta |
front 41 Which process in the thick ascending limb is a major contributor to the renal medullary solute gradient? A) Passive water secretion into lumen B) Active Na+ transport outward C) Albumin diffusion into interstitium D) Glucose secretion into medulla | back 41 B. Active Na+ transport outward |
front 42 Which combination best describes a key solute-building mechanism in the renal medulla? A) Na+, K+, Cl− leave thick limb B) Water leaves thick ascending limb C) Albumin enters collecting duct D) Glucose accumulates in medulla | back 42 A. Na+, K+, Cl− leave thick limb |
front 43 The collecting duct contributes to renal medullary hyperosmolarity through which process? A) Active ion transport into interstitium B) Protein filtration into tubule C) Water pumping into lumen D) Glucose reabsorption into cortex | back 43 A. Active ion transport into interstitium The collecting duct helps make the medulla hyperosmotic by moving solute out of the tubular fluid and into the medullary interstitium. |
front 44 Urea becomes highly concentrated in medullary collecting duct fluid. Which process helps build medullary interstitial osmolarity? A) Urea filtration into Bowman space B) Urea secretion into proximal tubule C) Urea diffusion into medulla D) Urea metabolism in cortex | back 44 C. Urea diffusion into medulla |
front 45 Why does the renal medulla remain highly hyperosmotic instead of being diluted by water movement? A) Thick limb pumps water outward B) Little water enters interstitium C) Glomeruli remove medullary water D) Albumin traps cortical water | back 45 B. Little water enters interstitium |
front 46 Which set best summarizes major contributors to medullary hyperosmolarity? A) Protein filtration, glucose secretion, ADH loss B) NaCl transport, urea diffusion, limited water C) Cortical dilution, albumin uptake, bicarbonate loss D) Potassium secretion, glucose filtration, high flow | back 46 B. NaCl transport, urea diffusion, limited water |
front 47 A renal physiologist blocks solute transport from the thick ascending limb into the medullary interstitium. Which renal function is most directly impaired? A) Medullary gradient formation B) Glomerular protein filtration C) Bladder sympathetic synapse D) External sphincter relaxation | back 47 A. Medullary gradient formation |
front 48 A patient with impaired renal medullary hyperosmolarity cannot concentrate urine despite ADH release. Which explanation best matches the normal role of the medulla? A) It filters plasma proteins B) It provides osmotic pull C) It secretes ADH centrally D) It contracts the bladder | back 48 B. It provides osmotic pull |
front 49 Which paired systems primarily regulate extracellular fluid sodium concentration and osmolarity under normal physiology? A) Aldosterone and ANP B) Osmoreceptor-ADH and thirst C) Sympathetics and renin D) Natriuresis and potassium | back 49 B. Osmoreceptor-ADH and thirst |
front 50 A patient’s plasma osmolarity rises after water deprivation, triggering hypothalamic sensing that increases ADH release. Where are the specialized osmoreceptor cells located? A) Posterior pituitary B) Adrenal cortex C) Renal medulla D) Anterior hypothalamus | back 50 D. Anterior hypothalamus |
front 51 A lesion near the third ventricle disrupts ADH secretion, thirst, sodium appetite, and blood pressure regulation. Which region is most likely damaged? A) AV3V region B) Area postrema C) Median eminence D) Suprachiasmatic nucleus | back 51 A. AV3V region |
front 52 A researcher studies circumventricular organs that can sense plasma osmolarity because their vascular supply lacks normal blood-brain solute impermeability. Which pair is most relevant? A) SFO and OVLT B) Hippocampus and amygdala C) Pons and medulla D) Cerebellum and thalamus | back 52 A. SFO and OVLT SFO = subfornical organ These are circumventricular organs, meaning they have a weaker blood-brain barrier. |
front 53 Why can the subfornical organ and OVLT participate in osmotic sensing despite being near the brain? A) They secrete aldosterone locally B) They lack neuronal osmoreceptors C) They drain into renal veins D) They lack typical BBB impermeability | back 53 D. They lack typical BBB impermeability |
front 54 A patient loses blood volume, activating cardiopulmonary and arterial pressure afferents that help trigger ADH release. Which cranial nerves carry these afferent signals? A) CN III and CN VII B) CN IX and CN X C) CN V and CN XII D) CN I and CN II | back 54 B. CN IX and CN X |
front 55 Signals from glossopharyngeal and vagal afferents relay cardiovascular volume-pressure information before hypothalamic ADH activation. Which brainstem nucleus receives these inputs? A) Red nucleus B) Dentate nucleus C) Nucleus solitarius D) Edinger-Westphal nucleus | back 55 C. Nucleus solitarius low blood volume/pressure → CN IX and CN X afferents → nucleus solitarius → hypothalamus → ADH release |
front 56 Afferent signals from CN IX and CN X reach the nucleus solitarius during hypovolemia. What is the next major relay effect relevant to water conservation? A) Direct collecting duct insertion B) Adrenal medulla catecholamine release C) Renal sympathetic shutdown D) Hypothalamic nuclei trigger ADH | back 56 D. Hypothalamic nuclei trigger ADH |
front 57 What is alcohol’s effect on ADH? A) Inhibits ADH B) Stimulates ADH C) Mimics ADH at V2 D) Converts ADH to oxytocin | back 57 A. Inhibits ADH |
front 58 A lesion in the AV3V region reduces a patient’s drive to drink despite hyperosmolar extracellular fluid. Which function is most directly impaired? A) Micturition B) Urea recycling C) Thirst generation D) Renin secretion | back 58 C. Thirst generation |
front 59 A dehydrated patient has increased extracellular fluid osmolarity and reduced effective circulating volume. Which response is most strongly stimulated? A) Bicarbonate secretion B) Thirst C) Protein filtration D) Potassium excretion | back 59 B. Thirst |
front 60 Which combination includes the most important physiologic stimuli for thirst? A) Low ADH, high calcium B) Low potassium, high glucose C) High albumin, low urea D) High ECF osmolarity, low volume-pressure | back 60 D. High ECF osmolarity, low volume-pressure |
front 61 What is the direct relationship between angiotensin II and thirst? A) Angiotensin II stimulates thirst B) Angiotensin II inhibits thirst C) Thirst suppresses angiotensin II D) Thirst blocks renin release | back 61 A. Angiotensin II stimulates thirst |
front 62 Why is the ADH-thirst system more directly responsible for normal sodium concentration regulation than aldosterone? A) It changes plasma proteins B) It regulates body water balance C) It blocks sodium filtration D) It secretes sodium into urine | back 62 B. It regulates body water balance |