University of Waterloo: BIOL 373 Midterm Exam 2 Answered Fall 2025/2026.

BIOL 373 MIDTERM 2 Highlighted in Green = Confirmed Right Answer Highlighted in Yellow = Need to double check Highlighted in this = friend’s test 1. Kidneys participate all but one of the following, identify the EXCEPTION: a) Regulation of plasma protein concentrations b) Regulation of acid-base balance c) Regulation of Na+ homeostasis d) Regulation of plasma osmolarity e) Regulation of extracellular fluid volume 2. An unusual vascular arrangement found in nephrons includes… a) Two capillary beds b) Portal vein c) Two arterioles d) A and C e) A B and C 3. Below are four process involved in ‘’ ‘“ Reabsorption: movement from tubular lumen to blood Filtration: Movement from glomerulus to lumen of tubule Excretion: movement from tubular lumen to external environment Secretion: movement from peritubular capillaries to lumen of tubule 4. Place the following blood vessels that carry blood within a juxtamedullary nephron in the order in which blood passes through them Afferent arteriole - glomerulus - efferent arteriole - peritubular capillaries - vasa recta 5. Whether a molecule is filtered at the glomerulus depends on… a) The presence of specific carriers for that molecule on glomerular capillary endothelium b) Plasma vasopressin concentrations c) It’s size and charge d) A and C e) A, B and C 6. All of the following are freely filtered at the glomerulus EXCEPT a) Plasma proteins b) Glucose c) Erythrocytes d) Potassiume) A and C 7. The main force driving glomerular filtration is the a) ATP-dependent processes in the nephron b) Plasma oncotic pressure c) Osmotic pressure in the glomerular capillaries d) Fluid pressure in the bowman’s capsule e) Blood pressure in the glomerular capillaries 8. Measurements in a nephron reveal a glomerular hydrostatic pressure of 69 mmHg, and a fluid pressure in the bowman’s capsule of 15 mmHg. If the colloid osmotic pressure of plasma in 30 mmHg and no plasma proteins are filtered by the glomerulus, what is the net glomerular filtration pressure? a) -6 mm Hg b) 24 mm Hg c) 54 mm Hg d) 84 mm Hg e) 114 mm Hg Equations: 9. Your uncle has been diagnosed with hypertension. His mean arterial pressure is moderately elevated at 140 mmHg. You would expect his glomerular filtration rate (GFR) to be __. a) Elevated b) Normal c) Reduced 10. Which is NOT part of the barrier for renal filtration? a) Apical membrane of proximal tubule epithelium b) Basement membrane of glomerular capillaries c) Sieve (meshwork) over filtration formed by specialized proteins d) Podocyte foot processes e) Glomerular capillary endothelium11. Which statement is true about renal blood flow and glomerular filtration rate (GFR) a. In response to minor increases in systemic blood pressure, afferent arterioles will constrict, resulting in a relatively constant renal blood flow and GFR b. Because renal blood flow is driven by systemic arterial pressure, renal blood flow and GFR will fluctuate with minor changes in systemic blood pressure c. The most important regulator of renal blood flow and GFR is the autonomic nervous system d. The most important regulator of renal blood flow and GFR are hormones from the posterior pituitary and adrenal glands e. in response to minor increases systemic blood pressure, afferent arterioles will dilate, resulting in a relatively constant renal blood flow and GFR 12. When fluid flows through the distal tubule increases as a result of increased GFR… a) The macula densa cells will release a paracrine messenger that causes constriction of the afferent arteriole of that nephron b) Renin will be released from granular (JG) cells in the juxtaglomerular apparatus c) Parasympathetic innervation to the associated afferent arteriole will increase, leading to vasodilation and decreased GFR d) Tonic sympathetic innervation to the associated afferent arteriole will decrease, leading to vasoconstriction and decreased GFR 13. Large plasma proteins ( i.e. fibrinogen, MW = 340 kDA) would likely be a) Too large to cross the glomerular filtration barrier and therefore remain in the plasma b) Filtered at the glomerulus then taken into the proximal tubule epithelial cells by endocytosis c) Filtered at the glomerulus and excreted in the urine d) Degraded by proximal tubule epithelial cells and recycled back into the circulation as amino acid e) Both B and D are true 14. A protein hormone with a molecular weight of 28 kDA would likely be… a) Too large to cross the glomerular filtration barrier and therefore remain in the plasma b) Filtered at the glomerulus then taken into the proximal tubule epithelial cells by endocytosis c) Filtered at the glomerulus and excreted in the urine d) Degraded by proximal tubule epithelial cells and recycled back into the circulation as amino acid e) Both B and D are true 15. Glucose and many amino acids are reabsorbed across the apical surface of proximal tubule epithelium bya) Cotransport with sodium b) Ion channels c) Leak channels d) Active transport e) Facilitated diffusion 16. Secondary transport is best described as… a) Cotransport of two different solutes across a membrane in opposite directions b) Cotransport of two different solutes across a membrane in the same direction c) Transport of a solute across a membrane against its concentration gradient by an ATPase transporter d) Transport of a solute across a membrane down it’s gradient by coupling it to the gradient for an ion that was generated/maintained by an ATPase driven pump e) Transport of a solute across a membrane up or down it’s gradient by coupling it to the gradient for an ion that was generated/maintained by an ATPase driven pump 17. Solutes in the peritubular capillaries are transported into renal tubules by.... a) Micturition b) Excretion c) Reabsorption d) Secretion e) Filtration 18. Beta-lactam antibiotics such as penicillin are eliminated by the kidneys. Secretion of penicillin at the proximal tubule would involve… a) Generation of a dicarboxylate gradient across epithelial cell membranes by co-transport of dicarboxylates with Na+ b) Primary active transport c) Bringing penicillin into the epithelial cells by exchange with dicarboxylates d) A and C e) A, B and C 19. OAT (organic ion transporter) proteins…a) Move organic anions from the interstitial fluid into the renal epithelial cells b) Move organic anions from the filtrate into the renal epithelial cells c) Are symports that cotransport organic anions with dicarboxylates such as alphaketoglutarate d) A and C e) B and C 19. OAT (organic ion transporter) proteins … a) Move organic anions from the interstitial fluid into the renal epithelial cell b) Move organic anions from the filtrate into the renal epithelial cell c) Exchange organic anions for dicarboxylates such as alphaketogluterate d) A and C e) B and C 20. Probenecid is on the WADA list of banned substances. This compound… a) Enhances renal clearance of known performance-enhancing drugs b) Reduces renal clearance of known performance-enhancing drugs c) Competes with other organic anions for the OAT transporter d) A and C e) B and C 21. The ____ refers to the plasma concentration at which all the renal carriers for a given substance are saturated. a) Transport maximum b) Tubuloglomerular capacity c) Renal threshold d) Saturation point e) Set point 22. Loss-of-function mutations in the protein nephrin would most likely be associated with…. a) Impaired tubuloglomerular feedback b) Decreased expression of transporters on the apical membranes of proximal tubule epithelium c) A leaky filtration barrier at the glomerular capillaries d) Vasoconstriction of the afferent arterioles leading to a reduced glomerular filtration rate e) Deficiency of renin secretion from granular cells23. If a patient has a plasma glucose concentration of 415 mg/100 mL, which of the following is/are true? a) The reabsorption rate of glucose is 400 mg/min b) Glucose will be freely filtered but not completely reabsorbed. c) This person likely has diabetes mellitus d) A and C e) A, B, and C 24. If a patient has a plasma glucose concentration of 200 mg/100 mL, which of the following is/are true. a) The reabsorption rate of glucose is 250 mg/min b) Glucose will be freely filtered but not completely reabsorbed. c) This person likely has diabetes mellitus. d) A and C e) A,B, and C 25. Inulin is … a) A hormone involved in carbohydrate metabolism in mammals. b) A storage carbohydrate found in many plants. c) A molecule that is freely filtered by the human kidney and neither reabsorbed nor secreted. d) A and C e) B and C 26. Why is creatinine used for routine assessment of renal function in humans? a) Creatinine is only filtered whereas insulin is both filtered and secreted. Thus creatinine gives a more accurate estimation of filtration rate. b) Creatinine is not normally present in humans, so results are not complicated by endogenous levels. c) Creatinine is endogenously produced at a constant rate, so no intravenous infusions are necessary. d) A and B e) A and C27. As part of your co-op position with a pharmaceutical company, you are asked to report on renal handling of a new antibiotic. You calculated GFR to be 115 mL/min. The plasma concentration of the drug is 5.44 mg/mL. In a 24 hour urine sample collection of 1.1 L, the concentration of the drug is 855 mg/mL. You conclude the substance is.... a) Almost completely retained in the body b) Not filtered c) Filtered and secreted d) Excreted in the feces e) Almost completely reabsorbed Use the following data for the next two questions: 28. What is this mf Omar’s GFR (glomerular filtration rate) a) 0.69 mL/min b) 30 mL/min c) 41.7 mg/min d) 69 mL/min e) 1,000 mL/min 29. Using GFR as the indicator of renal function, which of the following statements is true about Omar? a) His GFR is higher than normal, so his glomerular capillaries are likely damaged.b) His GFR is normal so his kidneys are probably OK. c) We have not been given enough information to estimate Omar’s GFR. d) His GFR is about half normal, so he has likely sustained kidney damage. 30. Micturition (urination) involves... a) Increased parasympathetic output to smooth muscles of the bladder. b) Increased sympathetic output to smooth muscles of the bladder. c) Inhibition of somatic motor neurons that normally keep the external sphincter contracted. d) A and C e) B and C 31. The osmoreceptors believed to be primary regulators of plasma osmolarity are located in the a) Pons b) Venous drainage of the intestine c) Kidney d) Medulla oblongata e) Hypothalamus 32. Osmoreceptors decrease their firing rate after they ______ in response to ______ plasma osmolarity. a) Shrink, decreased b) Shrink, increased c) Swell, decreased d) Swell, increased 32. Osmoreceptors increase their firing rate after they _____ in response to _____ plasma osmolarity a. shrink , decreased b. Shrink, increased c. Swell, decreased d. Swell, increased 33. Vasopressin … a) Causes diuresis b) Reduces the volume of urine output c) Is secreted in response to decrease in plasma osmolarity d) Stimulates the kidney to reabsorb sodium. e) Acts on the proximal tubule to increase water reabsorption.34. Vasopressin is produced by…. a) Magnocellular neurons that terminate in the posterior pituitary gland. b) Epithelial cells lining the proximal tubules. c) Granular cells within the juxtaglomerular apparatus of each nephron. d) Epithelial cells lining the collecting ducts. e) Osmoreceptors surrounding cerebral ventricles. 35. Vasopressin acts on epithelial cells in the distal nephron to … a) Increase activity of Na+/K+ ATPase on the basolateral membranes. b) Increase aquaporin expression on the apical surfaces. c) Increase salt reabsorption via secondary active transport. d) Increase expression of ENaC channels on the basolateral surface. e) Both B and D 36. Eating dry salty food without drinking will cause ______ in plasma osmolarity and _______ in the volume of body fluids. (before any compensatory responses) a) A decrease; a decrease b) An increase; an increase c) A decrease; an increase d) A decrease; no change e) An increase; no change 37. When your body is dehydrated, water in the urinary bladder will be…. a) Reabsorbed and returned to the circulation in the presence of certain hormones. b) Reabsorbed and returned to the circulation after moving back into the kidneys. c) Lost from the body via the urine. d) Reabsorbed and returned to the circulation. 38. The two organ systems that work together to regulate most aspects of blood volume and pressure are a) Digestive and cardiovascular b) Cardiovascular and respiratory c) Digestive and respiratory d) Renal and cardiovascular e) Renal and respiratory 39. Reabsorption is hormonally regulated in the …. a) Proximal tubule b) Collecting duct c) Loop of Henle d) Distal tubule e) B and D 40. The hormone that regulates water reabsorption/excretion by the kidneys acts ….a) On the proximal tubule to increase water permeability. b) On the distal nephron to decrease water permeability. c) On the proximal tubule to decrease water permeability. d) Throughout the renal tubules to regulate water permeability. e) On the distal nephron to increase water permeability. 41. Major function(s) of the loop of Henle is/are … a) Reabsorption of approximately 25% of the sodium and potassium from the glomerular filtrate. b) Water reabsorption via action of aldosterone in the ascending loop. c) Creation of a salt gradient in the renal medulla. d) A and C e) A, B and C 42. In humans, the highest osmolarity reached in the Loop of Henle is .... a) ~ 100 mOsM. b) ~ 300 mOsM. c) ~ 900 mOsM. d) ~ 1200 mOsM. e) Dependent on the level of vasopressin. Use the following information for the next two questions: A former house-mate mf named Kevin, has a genetic disease called diabetes insipidus. His underlying issue is a (loss-of-function) mutation in the gene that codes for the vasopressin hormone. 43. Which of the following would be true for Kevin? a) He tends to produce very concentrated urine. b) His condition could be treated with desmopressin (a vasopressin agonist). c) He tends to produce copious quantities of dilute urine. d) A and B e) B and C 44. While celebrating St Patties with friends including Kevin, one of your guests decides to test something your physiology prof said in class by tasting Kevin’s urine. With no need (or desire) to taste it yourself, you know that because of his disease, Kevin’s urine would be: a) Salty b) Full bodied with just the right touch of fruit flavour. c) Minty d) Bland, rather tasteless e) Sweet45. A loop diuretic a) Is a drug that blocks the effects of vasopressin at the distal nephrons b) Is a drug that inhibits the activity of renewal NKCC transporters in the loop of Henle c) Is a drug that blocks expression of aquaporins in the distal nephron d) Will reduce the transport of salt from the filtrate into epithelial cells lining the ascending limb of the loop of Henle e) Both B and D are true 46. The salt gradient in the renal medulla is important for… a) Reabsorption of water from collecting ducts b) Reabsorption of water from the proximal tubule c) The ability of vasopressin to regulate water conservation d) A and C are true e) A, B and C are true 47. Your other mf friend Dan has been lost in the desert for two days with very little water. He is suffering from dehydration. You would expect Dan to have… a) Normal urine production b) Decreased blood osmolarity c) Elevated vasopressin levels d) Increased blood volume e) Elevated aldosterone levels 48. Aldosterone is.... a) A peptide stored in membrane-bound vesicles in cells within the posterior pituitary b) A peptide stores in membrane-bound vesicles within the adrenal cortex c) A steroid produced by cells within the adrenal cortex d) A steroid produced by epithelial cells lining the distal nephron 49. Aldosterone acts… a) On an intracellular receptor express by P cells in the distal nephron b) On a membrane receptor expressed on the basolateral surfaces of P cells in the distal nephron c) By driving transcription of genes that code for proteins involved in Na+ reabsorption and K+ secretion d) A and C e) B and C 50. In response to hyperkalemia, you would expect… a) Increased K+ reabsorption at the distal nephron b) Increased K+ secretion at the distal nephron c) Increased Na+ reabsorption at the proximal tubule d) Elevating of circulating aldosteronee) B and D 51. Considering renal function in the presence of maximal concentrations of aldosterone… a) Most of the sodium filtered at the glomerulus is reabsorbed in the distal tubule and collecting duct b) There is increased expression of pumps and channels involved in sodium reabsorption in the proximal tubule c) Most of the sodium filtered at the glomerulus is reabsorbed in the proximal tubule d) A and B e) B and C 52. Which of the following statements concerning the hormone atrial natriuretic peptide is FALSE? a) It is produced by cells in the heart in response to increased stretch b) It suppresses vasopressin secretion c) It reduces the sensation of thirst d) It promotes sodium loss at the kidneys e) It increases aldosterone secretion 53. Angiotensin-converting enzyme (ACE) converts ______ and is expressed in _____ a) Angiotensinogen to angiotensin I; renal epithelial cells b) Angiotensinogen to angiotensin I; vascular endothelial cells c) Angiotensin I to angiotensin II; granular (G) or juxtaglomerular cells d) Angiotensin I to angiotensin II; vascular endothelial cells e) Angiotensin II to aldosterone; vascular endothelial cells 54: Situations that lead to the activation of the RAS pathway include…** WOAHH THE ANSWER FOR A IN THIS QUESTION IS DIFF IN MY FRIENDS** HERS IS a) Low blood pressure in renal afferent arterioles a) Elevated blood pressure in renal afferent arterioles b) An increase in sodium chloride flowing past the macula densa c) Increased sympathetic input from the cardiovascular control centre in the medulla acting on granular (G) cells d) A and C e) A, B and C 55. Angiotensin II… a) Causes vasopressin release from the hypothalamus b) Increases cardiac output c) Causes the synthesis and release of aldosterone from the adrenal cortex d) A and C e) A, B and C 56. ACE inhibitors would be useful drugs for treatment ofa) Metabolic acidosis b) Male pattern baldness c) Diabetes insipidus d) Hypertension e) Dizziness due to blood loss 57. In response to severe hemorrhage you would expect… a) Increased sympathetic output from the cardiovascular control centre b) Increased parasympathetic output from the cardiovascular control centre c) Increased heart rate d) Decreased cardiac output e) A and C 58. In a case of volume depletion due to extreme sweating combined resulting in hyperosmolarity, in the compensatory response you would expect… a) A rapid pulse b) Elevated aldosterone c) Elevated vasopressin d) A and C e) A, B and C 59. The two organ systems that work together to regulate the body’s acid-base balance are a) Digestive and respiratory b) Digestive and cardiovascular c) Cardiovascular and respiratory d) Renal and respiratory e) Renal and cardiovascular 60. The main factor affecting blood pH under normal conditions is the plasma concentration of a) Lactic acid b) Ketone bodies c) Organic acids d) Hydrochloric acid e) Carbon dioxide 61. In general renal compensation for alkalosis in the distal nephron involves… a) Pumping protons across the apical membrane into the tubular fluid b) Pumping protons across the basolateral membrane into the interstitium c) Reabsorbing more bicarbonate d) A and C e) B and C61. In general renal compensation for alkalosis in the distal nephron involves… a) Pumping protons across the basolateral membrane into the interstitium b) Pumping protons across the apical membrane into the tubular fluid c) Moving more bicarbonate into the filtrate d) A and C e) B and C 62. Hyperventilation (e.g due to exam-induced anxiety) will likely bring on... a) Metabolic alkalosis b) Metabolic acidosis (Hyperventilation occurs as a response to metabolic acidosis *check this) c) Respiratory acidosis d) Respiratory alkalosis 63. Regulatory responses to correct acid-base imbalances can influence K+ homeostasis due to… a) Activity of the H+/K+ -ATPase expressed on membranes of intercalated cells in the distal nephron b) Activity of the H+/K+ -ATPase expressed on membranes of epithelial cells in the proximal tubule c) Compensatory changes in respiratory rate d) Compensatory changes in carbonic anhydrase activity in renal epithelial cells e) A and C 64. Jasmine has normal PCO2 levels, low plasma pH and low plasma bicarbonate level. What type of disturbance is she suffering from? a) Metabolic acidosis b) Respiratory alkalosis c) Metabolic alkalosis d) Respiratory acidosisAdditional - 15 ) The typical pattern for molecules reabsorbed by Na+ -dependent cotransport involves an apical ___ and a basolateral ___. a) Facilitated diffusion carrier, osmotic gradient b) Symport protein, osmotic gradient c) Osmotic gradient, symport protein d) Facilitated diffusion carrier, symport protein e) Symport protein, facilitated diffusion carrier Aldosterone … a. Is secreted in response to hyperkalemia b. Increases sodium excretion c. Promotes sodium retention d. A and B e. A and C In the presence of maximal concentration of vasopressin and aldosterone, the ascending limb of the loop of Henle a. Continues to reabsorb salt at its usual rate b. Increases reabsorption of both water and salt c. Increases it secretion of salt d. Increases its reabsorption of salt e. Continues to secrete salt at its usual rate