Question 1

A particular epithelium has a paracellular (between the cells) pathway permeable to water and chloride. In order to enhance the net movement of NaCl and water from apical to basolateral portions of the cell, the epithelium needs:

Accepted Answer

The correct choice is A because it describes the necessary components for effective NaCl and water transport across epithelial cells: a basolateral Na+/K+-ATPase to actively pump Na+ out of the cell (creating a low intracellular Na+ concentration that drives Na+ entry at the apical side), basolateral K+ channels to allow K+ to recycle back into the extracellular space (maintaining the electrochemical gradient), and apical Na+ channels to allow Na+ entry into the cell from the apical side. This setup creates a net movement of NaCl from the apical to the basolateral side, with water following osmotically through the paracellular pathway.

Question 2

Some tumor cells have a large number of Cl^- channels on the plasma membrane. This makes the Cl^-permeability higher than that of any other ion and therefore:

Accepted Answer

The high Cl^- permeability means that the membrane potential is likely to be close to the equilibrium potential for Cl^-, as the ion with the highest permeability has the greatest influence on the membrane potential.

Question 3

An epithelial cell layer bathed in physiological saline solution on both apical and basolateral surfaces starts out in a steady state in which there is constant absorption of Na⁺, Cl^-, and H₂O. The addition of ouabain to the basolateral side will cause:

Accepted Answer

Ouabain inhibits the Na+/K+ ATPase pump, leading to an accumulation of Na+ inside the cell and a decrease in K+ inside the cell as the pump can no longer exchange intracellular Na+ for extracellular K+.

Question 4

A 36-year-old male patient with a recent head injury complains of polyuria. You suspect central diabetes insipidus. How could you confirm the diagnosis?

Accepted Answer

To confirm a diagnosis of central diabetes insipidus, a water deprivation test followed by administration of arginine vasopressin (AVP) can be used. If the patient has central diabetes insipidus, their ability to concentrate urine will be impaired due to a lack of AVP, but will improve after administration of AVP.

Question 5

A 30-year-old woman complains of extreme fatigue following even mild exercise. These symptoms become worse throughout the day. You diagnose this patient with myasthenia gravis (MG). In most patients with MG autoantibodies cause a decrease in:

Accepted Answer

Myasthenia gravis is an autoimmune disorder characterized by the production of autoantibodies against the acetylcholine receptors at the neuromuscular junction, leading to a decrease in the postsynaptic (endplate) potential. This impairs the ability of the muscle to contract in response to nerve impulses.

Question 6

Given the following data from a patient - urine output 1.5 L/day; plasma creatinine 1.0 mg/dL; urinary creatinine 1.2 mg/mL; plasma phosphate 0.002 mEq/mL; urinary phosphate 0.05 mEq/mL - what can you reliably conclude about the renal handling of phosphate?

Accepted Answer

The renal handling of phosphate primarily involves its reabsorption from the filtrate back into the bloodstream. Given the data, with a higher concentration of phosphate in the urine compared to plasma, it indicates that although phosphate is filtered, a significant portion is reabsorbed, as the body typically conserves phosphate due to its importance in various physiological processes. The fact that there is still phosphate present in the urine does not indicate net secretion or that it is neither secreted nor reabsorbed; rather, it shows that while phosphate is filtered, the majority is reabsorbed, which is a characteristic behavior of renal phosphate handling.

Question 7

A 44 year-old male presents to the emergency department with severe back pain radiating to the left flank. A radiological exam reveals a kidney stone partially blocking the ureter of one kidney. Based on your knowledge of renal physiology, which of the following statements is correct?

Accepted Answer

The presence of a kidney stone partially blocking the ureter can lead to increased pressure in the renal tubules upstream of the blockage, which can reduce the glomerular filtration rate (GFR) in the affected kidney due to the reduced ability of the kidney to filter blood effectively.

Question 8

Which statement is true about a 5 kg infant and his 50 kg mother?

Accepted Answer

The answer of Which statement is true about a 5...

Question 9

Lambert-Eaton Syndrome (LES) is similar to myasthenia gravis. In LES, which of the following is most affected during neuromuscular transmission?

Accepted Answer

Lambert-Eaton Syndrome (LES) primarily affects the release of acetylcholine (ACh) from the nerve terminal, leading to muscle weakness. This is due to antibodies against presynaptic calcium channels, which are crucial for ACh release.

Question 10

A 25-year-old female medical student from out of state wants to drive home over the 4th of July holiday. She hates to use public facilities and would prefer to minimize her urinary flow rate. Unfortunately, the air conditioning in her car is broken so she knows that she will have to consume 2-3 L of fluids to replace that lost due to sweating. What is her best choice to drink during the 8-hours to result in a minimum of rest room breaks?

Accepted Answer

Sports drinks are the best choice in this scenario because they contain electrolytes (like sodium and potassium) which help to retain fluid in the body, thus reducing urine output. This is in contrast to diuretics like coffee and soda, which increase urine production, and to plain water or sweetened tea, which do not contain electrolytes to aid in fluid retention.

Quiz 1: Introduction

A particular epithelium has a paracellular (between the cells) pathway permeable to water and chloride. In order to enhance the net movement of NaCl and water from apical to basolateral portions of the cell, the epithelium needs:

Some tumor cells have a large number of Cl^- channels on the plasma membrane. This makes the Cl^-permeability higher than that of any other ion and therefore:

An epithelial cell layer bathed in physiological saline solution on both apical and basolateral surfaces starts out in a steady state in which there is constant absorption of Na⁺, Cl^-, and H₂O. The addition of ouabain to the basolateral side will cause:

A 36-year-old male patient with a recent head injury complains of polyuria. You suspect central diabetes insipidus. How could you confirm the diagnosis?

A 30-year-old woman complains of extreme fatigue following even mild exercise. These symptoms become worse throughout the day. You diagnose this patient with myasthenia gravis (MG) . In most patients with MG autoantibodies cause a decrease in:

Given the following data from a patient - urine output 1.5 L/day; plasma creatinine 1.0 mg/dL; urinary creatinine 1.2 mg/mL; plasma phosphate 0.002 mEq/mL; urinary phosphate 0.05 mEq/mL - what can you reliably conclude about the renal handling of phosphate?

A 44 year-old male presents to the emergency department with severe back pain radiating to the left flank. A radiological exam reveals a kidney stone partially blocking the ureter of one kidney. Based on your knowledge of renal physiology, which of the following statements is correct?

Which statement is true about a 5 kg infant and his 50 kg mother?

Lambert-Eaton Syndrome (LES) is similar to myasthenia gravis. In LES, which of the following is most affected during neuromuscular transmission?

Quiz 1: Introduction

A particular epithelium has a paracellular (between the cells) pathway permeable to water and chloride. In order to enhance the net movement of NaCl and water from apical to basolateral portions of the cell, the epithelium needs:

Some tumor cells have a large number of Cl- channels on the plasma membrane. This makes the Cl- permeability higher than that of any other ion and therefore:

An epithelial cell layer bathed in physiological saline solution on both apical and basolateral surfaces starts out in a steady state in which there is constant absorption of Na+, Cl-, and H2O. The addition of ouabain to the basolateral side will cause:

A 36-year-old male patient with a recent head injury complains of polyuria. You suspect central diabetes insipidus. How could you confirm the diagnosis?

A 30-year-old woman complains of extreme fatigue following even mild exercise. These symptoms become worse throughout the day. You diagnose this patient with myasthenia gravis (MG) . In most patients with MG autoantibodies cause a decrease in:

Given the following data from a patient - urine output 1.5 L/day; plasma creatinine 1.0 mg/dL; urinary creatinine 1.2 mg/mL; plasma phosphate 0.002 mEq/mL; urinary phosphate 0.05 mEq/mL - what can you reliably conclude about the renal handling of phosphate?

A 44 year-old male presents to the emergency department with severe back pain radiating to the left flank. A radiological exam reveals a kidney stone partially blocking the ureter of one kidney. Based on your knowledge of renal physiology, which of the following statements is correct?

Which statement is true about a 5 kg infant and his 50 kg mother?

Lambert-Eaton Syndrome (LES) is similar to myasthenia gravis. In LES, which of the following is most affected during neuromuscular transmission?

Some tumor cells have a large number of Cl^- channels on the plasma membrane. This makes the Cl^-permeability higher than that of any other ion and therefore:

An epithelial cell layer bathed in physiological saline solution on both apical and basolateral surfaces starts out in a steady state in which there is constant absorption of Na⁺, Cl^-, and H₂O. The addition of ouabain to the basolateral side will cause: