Question 1

Which of the following best explains why hypokalemia leads to muscle weakness and cardiac arrhythmias?

Accepted Answer

Low $$K^+$$ levels cause the resting membrane potential to become hyperpolarized, making cells farther from threshold.

Question 2

A patient presents with high blood potassium ($$K^+) $$levels. Which of the following is the most likely effect on their neurons' resting membrane potential (RMP)?

Accepted Answer

RMP becomes less negative, making cells closer to threshold.

Question 3

Which part of the nephron is impermeable to potassium ($$K^+$$)?

Accepted Answer

Descending limb of the nephron loop

Question 4

Approximately what percentage of filtered potassium ($$K^+) is $$reabsorbed before entering the nephron loop?

Accepted Answer

65-70%

Question 5

Why does the filtrate remain isosmotic with plasma as it passes through the proximal convoluted tubule (PCT)?

Accepted Answer

Because salts and water are removed in proportionate amounts.

Question 6

The nephron loop creates a corticomedullary gradient. What is the primary function of this gradient?

Accepted Answer

To enable urine concentration by providing a driving force for water reabsorption.

Question 7

Which of the following best describes the permeability of the nephron loop's descending and ascending limbs?

Accepted Answer

Descending limb: permeable to water, not salt; Ascending limb: impermeable to water, permeable to salt

Question 8

A patient is given an antidiuretic hormone (ADH) analog. What is the expected effect on their urine?

Accepted Answer

Urine volume decreases and osmolality increases.

Question 9

Alcohol consumption leads to increased urination. What is the physiological mechanism behind this effect?

Accepted Answer

Alcohol suppresses pituitary gland ADH secretion, reducing water reabsorption.

Question 10

Which of the following is TRUE regarding diabetes insipidus?

Accepted Answer

It results in the inability to properly concentrate urine, leading to polyuria and polydipsia.

Question 11

A patient with nephrogenic diabetes insipidus would have which of the following abnormalities?

Accepted Answer

Kidneys do not respond to ADH

Question 12

Which of the following statements about inulin is CORRECT?

Accepted Answer

Inulin is a fructose polymer produced by plants and is safe for people with diabetes.

Question 13

Why is inulin clearance considered the gold standard for measuring glomerular filtration rate (GFR)?

Accepted Answer

Inulin is freely filtered, not reabsorbed, secreted, or metabolized by the kidney.

Question 14

Given the following data from an inulin clearance test: urine formation rate $$V = 1.5\ \mathrm{mL/min}$$, urine inulin concentration $$U = 30\ \mathrm{mg/mL}$$, plasma inulin concentration $$P = 0.5\ \mathrm{mg/mL}$$, what is the glomerular filtration rate (GFR)?

Accepted Answer

$$GFR = \dfrac{V 	imes U}{P} = \dfrac{1.5 	imes 30}{0.5} = 90\ \mathrm{mL/min}$$

Question 15

If a patient’s urine formation rate is $$2.0\ \mathrm{mL/min}$$ and urine inulin concentration is $$25\ \mathrm{mg/mL}$$, what is the rate of inulin excretion?

Accepted Answer

$$2.0 	imes 25 = 50\ \mathrm{mg/min}$$

Question 16

Which formula correctly calculates the glomerular filtration rate (GFR) using inulin clearance?

Accepted Answer

$$GFR = \dfrac{V_{(\mathrm{mL/min})} 	imes U_{(\mathrm{mg/mL})}}{P_{(\mathrm{mg/mL})}}$$

Question 17

A patient’s plasma inulin concentration is $$0.4\ \mathrm{mg/mL}$$, urine formation rate is $$1.2\ \mathrm{mL/min}$$, and urine inulin concentration is $$40\ \mathrm{mg/mL}. $$What is the rate of filtration of inulin?

Accepted Answer

$$RF = GFR 	imes P = 120 	imes 0.4 = 48\ \mathrm{mg/min}$$

Question 18

Which of the following is a function of the vasa recta in the kidney?

Accepted Answer

Traps $$NaCl in $$the medullary interstitial fluid, helping maintain the osmotic gradient.

P: Urinary System 3

Study Guide - Practice Questions

Study Guide - Flashcards