Renal Physio MCQ Flashcards
- In the presence of vasopressin, the greatest fraction of filtered water is absorbed in the:
a. Proximal tubule
b. Loop of Henle
c. Distal tubule
d. Cortical collecting duct
e. Medullary collecting duct
a. Proximal tubule
greatest fraction of filtered water will always be absorbed from the PCT, irrespective of ADH action. In general, most reabsorption of substances (water, electrolytes, glucose, etc) takes place in the PCT.
- A freely filtered substance with plasma concentration of 2mg/mL, GFR of 100mL/min, urine concentration of 10mg/mL, urine flow rate of 5mL/min.
a. Reabsorbed 150mg/min
b. Reabsorbed 200mg/min
c. Secreted 50mg/min
d. Secreted 150mg/min
e. Secreted 200mg/min
a. Reabsorbed 150mg/min
Amount that goes to glomerulus is 2x100 = 200mg/min
Amount that is excreted in urine is 10x5 = 50mg/min
Therefore the difference is the amount reabsorbed ie 200-50=150mg/min.
- Which of the following is not a potential cause of hypertonicity in the body?
a. Water deprivation
b. Massive sweating
c. Massive secretion of vasopressin
d. Diabetes insipidus
e. Severe diarrhea
c. Massive secretion of vasopressin
- As a result of counter-current exchange, the fluid in the tubule is most hyperosmotic in the:
a. Proximal convoluted tubule
b. Distal convoluted tubule
c. Ascending limb
d. Descending limb
e. Tops of the Loop of Henle
d. Descending limb
- What does dilation of the efferent arterioles do?
a. Increase GFR
b. Increase glomerular blood flow
b. Increase glomerular blood flow
- What happens to the GFR as the blood flows from afferent to efferent arterioles?
a. Increase
b. Decrease
c. No change
d. Increase, reaches a maximum, then decrease
e. Decreases, reaches a minimum, then increase
b. Decrease
As more small molecules are filtered out, plasma oncotic pressure increases and capillary hydrostatic pressure decreases, thus net filtration decreases throughout from afferent to efferent arterioles.
- ADH secretion and release is caused by:
a. Drinking 2L of distilled water
b. Drinking 2L of hypertonic saline (sea water)
c. Drinking 2L of isotonic saline
d. Drinking 2L of isotonic glucose
e. None of the above because increase in volume inhibits ADH secretion
b. Drinking 2L of hypertonic saline (sea water)
- Aldosterone:
a. Increases reabsorption of potassium at the proximal convoluted tubules
b. Secretion is stimulated by high blood potassium levels
c. Increases secretion of renin
d. Can lead to development of metabolic acidosis
b. Secretion is stimulated by high blood potassium levels
- A plasma pH of 7.32 may
a. Lead to inhibition of respiration
b. Cause Hb to have a lower affinity
c. Arise due to lower CO2 content in the blood
d. Lead to less renal excretion of H+ ions
e. Arise due to pulmonary hypertension
b. Cause Hb to have a lower affinity
- ADH deficiency may lead to all of the following except:
a. Increased urine output
b. Increased thirst
c. Increased urinary sodium excretion
d. Urinary osmolality of <200mOsm/kg
e. Increased plasma osmolality
c. Increased urinary sodium excretion
- ADH secretion is increased by all of the following factors except:
a. Increase in plasma osmolality
b. Loss of blood
c. Pain
d. Vomiting
e. Alcohol
e. Alcohol
The two main triggers of ADH secretion are increased osmolality (A) and decreased volume (B & D). Pain (C) may also increase ADH secretion but the mechanism is unclear. Alcohol (E) inhibits ADH secretion (mechanism is also not well understood). Consequently, the kidneys produce more urine, leading to excessive urination and possible dehydration.
- Increased aldosterone secretion by an adrenal tumour may cause all of the following except:
a. Hypertension
b. Muscle weakness
c. A low plasma potassium concentration
d. Decreased urine volume
e. Low plasma renin activity
d. Decreased urine volume
A: Aldosterone excess may result in increased blood pressure (RAAS mechanism).
B and C: Aldosterone increases potassium secretion, which when excessive can lead to hypokalemia (a low plasma potassium conc) and muscle weakness.
D: Increased aldosterone secretion will lead to increased reabsorption of sodium and water. This increased volume will trigger a compensatory reduction in ADH secretion, which will decrease water reabsorption at the collecting duct and thus increase or maintain (not decrease) urine volume.
Option E: Aldosterone decreases renin activity via negative feedback on the RAAS system.
- Respiratory compensation for metabolic alkalosis cannot be complete as
a. Low PaCO2 stumulates respiration
b. High PaCO2 stimulates respiration
c. Low PaCO2 inhibits respiration
d. High PaCO2 inhibits respiration
e. None of the above, as respiratory compensation for metabolic alkalosis can be complete
b. High PaCO2 stimulates respiration
- Why does eating a very salty snack make you thirsty?
a. ECF volume decreases
b. ECK osmolarity decreases
c. It would inhibit the hypothalamic chemoreceptors
d. It would stimulate the hypothalamic osmoreceptors
e. It would immediately cause a rise in urine output
d. It would stimulate the hypothalamic osmoreceptors
- Vasopressin
a. Causes plasma to be osmolar
b. Completely halts urine output
c. Causes distal and collecting tubules to become impermeable to water
d. Results in hyperosmolar urine output
d. Results in hyperosmolar urine output
- Inulin and substance X were found in the kidney. Ratio of inulin to X was 2:1 initially in the early tubule of the kidney but after which in later portions of the kidney the ratio became 1:1
a. Substance X is secreted
b. Inulin is reabsorbed
c. X is reabsorbed
d. Inulin is secreted
a. Substance X is secreted
Inulin is freely filtered, not secreted and not reabsorbed (that’s why it’s preferred for measuring GFR). Since the amount of Substance X was originally half that of inulin but later doubled (increased) to become equal, Substance X must have been secreted by the renal tubule (for its amount in the tubule to have increased).
- In a severely dehydrated patient, this is the best infusion to give:
a. 0.9% sodium
b. 5% glucose
c. hypertonic solution
d. isotonic saline
a. 0.9% sodium
d. isotonic saline
both are same
- Which of the following substances are not regulated by the kidneys?
a. Glucose
b. Sodium
c. Hydrogen
d. Phosphate
e. Water
a. Glucose
- X has diarrhoea for 2 days. His pH is 7.3, CO2 is 40mmHg, bicarbonate concentration is 18mmol/L. what acid base disorder does he have?
a. Metabolic acidosis
b. Metabolic alkalosis
c. Respiratory acidosis
d. Respiratory alkalosis
e. Both
a. Metabolic acidosis
pH is below normal, PaCO2 is normal, [HCO3-] is below normal. This indicates simple (uncompensated) metabolic acidosis. In this case, this is due to the loss of alkaline (bicarbonate-rich) intestinal fluid as a result of the diarrhoea.
- Oat cell carcinoma causes excessive production of ADH. What other condition mimics this condition?
a. Moderate hemorrhage
b. Excessive salt intake
c. Excessive water intake
d. Renal failure
e. Evaporative dehydration
b. Excessive salt intake
d. Renal failure
e. Evaporative dehydration
A: severe haemorrhage is required before ADH is produced excessively. blood volume falls so greatly that “survival is threatened” and the body sacrifices osmolarity for increasing blood volume.
B: best answer out of the given options. consumption of excessive amounts of salt will cause the body to produce a lot more ADH.
D: Renal failure patients are unable to regulate serum osmolarity, ie unable to excrete excess sodium. This results in excessive ADH production.
E: Dehydration leads to increase ADH production
It is noteworthy that chronic kidney disease causes hyponatremia instead of hypernatremia
- Carbonic anhydrase inhibitor is expected to lead to
a. Increased urinary acid excretion
b. Increased bicarbonate reclamation
c. Metabolic alkalosis
d. Decreased bicarbonate regeneration
d. Decreased bicarbonate regeneration
Option D: Carbonic anhydrase is important for the regeneration of new bicarbonate (and hydrogen ion excretion) in the distal parts of the renal tubule. A carbonic anhydrase inhibitor will thus decrease bicarbonate regeneration and urinary acid excretion, leading to a metabolic acidosis.
- What causes a high serum anion gap?
a. Metabolic alkalosis
b. Vomiting
c. Respiratory alkalosis
d. Respiratory acidosis
e. Metabolic acidosis
d. Respiratory acidosis
e. Metabolic acidosis
- If you took a drug that inhibited the reabsorption of Na+ in the PCT, you would
a. Have an increased urine output
b. Have a decreased urine output
c. Have a decreased plasma [bilirubin] and become jaundiced
d. Have decreased absorption of fats and have grey-white feces
a. Have an increased urine output
- Glucose is
a. Filtered, reabsorbed, and secreted
b. Filtered, and reabsorbed, but not secreted
c. Filtered, and secreted, but not reabsorbed
d. Filtered, and neither secreted nor reabsorbed
b. Filtered, and reabsorbed, but not secreted
- If mean arterial pressure (MAP) increased from 120mmHg to 154mmHg, GFR would most likely
a. Increase
b. Decrease
c. Stay the same
c. Stay the same
autoregulation
- Typically, as GFR increases, the [Na+] of the filtrate reaching the DCT will
a. Increase
b. Decrease
c. Stay the same
a. Increase
As GFR increases, more Na+ is filtered across than can be reabsorbed; thus, the [Na+] of the filtrate reaching the DCT will increase.
- What would happen to the GFR if the hydrostatic pressure exerted by the fluid in the capsular space increased?
a. GFR would increase
b. GFR would decrease
c. GFR would not change
b. GFR would decrease
- While the kidneys process about 180L of blood-derived fluids per day, the amount that actually leaves the body is:
a. 50%, or 90L
b. 100%, or 180L
c. 10%, or 18L
d. 1%, or 1.8L
d. 1%, or 1.8L
- The fluid in the capsular space is similar to plasma except that it does not contain a significant amount of:
a. Glucose
b. Sodium
c. H+
d. Albumin
d. Albumin
- True or False: Glomerular filtration is an ATP-driven process
False: Filtration across the glomerular membrane is down a pressure gradient (from an area of high to low hydrostatic pressure) and is not an energy dependent process.
- Aldosterone causes:
a. Decreased K+ in the urine
b. Increased Na+ in the urine
c. Increased urine output
d. Decreased urine output
d. Decreased urine output
- Creatinine is a
a. Chemical that is typically not secreted
b. Substance typically found in greater amounts in renal arteries than in renal veins
c. Building block for complex carbohydrates
d. 2 of the above are correct
b. Substance typically found in greater amounts in renal arteries than in renal veins
- In humans, the thirst centre is located in the
a. Adrenal cortex
b. Pons
c. Hypothalamus
d. Medulla Oblongata
e. Thalamus
c. Hypothalamus
- The longer the ______________, the greater an animal’s capacity to conserve water and to concentrate the solutes excreted in the urine.
Loop of Henle
- Hormonal control of urinary excretion primarily affects:
a. Bowman’s capsules
b. DCTs and collecting ducts
c. PCTs and Loops of Henle
d. Urinary bladder
Option B: The main hormones which control urine production are aldosterone and ADH, which act primarily on the DCT and collecting duct.
- As dehydration increases, the release of ADH from the posterior pituitary will
a. Increase
b. Decrease
c. Stay the same
a. Increase
- The plasma protein concentration of a patient with untreated glomerulonephritis would be expected to be:
a. Greater than normal
b. Less than normal
c. Normal
b. Less than normal
In untreated glomerulonephritis, there is autoimmune damage to the filtration barrier of the glomerular membrane, resulting in (abnormally) large amounts of plasma proteins (eg albumin) being filtered across the membrane which cannot be reabsorbed and are lost in the urine. Thus, the plasma protein concentration of a patient with untreated glomerulonephritis would be expected to be lower the normal.
- Which of the following is NOT a function of atrial natriuretic peptide?
a. It acts to decrease aldosterone release from the adrenal cortex
b. It acts to increase urine output
c. It acts to increase blood pressure
d. It acts to decrease ADH release
c. It acts to increase blood pressure
Atrial natriuretic peptide (ANP) opposes the effects of aldosterone and the RAAS system; thus it decreases aldosterone and ADH release (Options A and D), increases urine output (Option B) and decreases (not increases) blood pressure (Option C).