CSR Renal Physiology & Pathophysiology 1 — Questions and Answers
Question 1: What is the primary function of the glomerulus in the nephron?
- Reabsorbs electrolytes.
- Concentrates urine.
- Filters blood to form primary urine (Correct answer)
- Secretes erythropoietin.
Correct answer: Filters blood to form primary urine
The glomerulus is a network of tiny blood vessels (capillaries) located at the beginning of a nephron in the kidney. Its primary function is ultrafiltration, where blood plasma, excluding large proteins and blood cells, is filtered from the capillaries into Bowman's capsule. This process forms the initial filtrate, or primary urine, which then proceeds through the rest of the nephron for further processing.
Question 2: Which hormone is most directly involved in sodium reabsorption in the distal nephron?
- ADH
- Aldosterone (Correct answer)
- Erythropoietin
- Renin
Correct answer: Aldosterone
Aldosterone is a mineralocorticoid hormone produced by the adrenal cortex that acts directly on the principal cells of the distal convoluted tubule and collecting duct in the kidney. Its primary function is to increase sodium reabsorption and potassium excretion. This action helps regulate blood pressure and maintain fluid balance within the body.
Question 3: What is the role of the loop of Henle in urine concentration?
- Eliminates toxins.
- Maintains blood pressure.
- Generates a medullary concentration gradient (Correct answer)
- Regulates blood glucose levels.
Correct answer: Generates a medullary concentration gradient
The loop of Henle is crucial for concentrating urine by establishing a medullary osmotic gradient through the countercurrent multiplier system. The descending limb is permeable to water, while the ascending limb actively transports solutes like sodium and chloride out of the tubule. This creates a hyperosmotic environment in the renal medulla, which is then utilized by the collecting ducts to reabsorb water, leading to concentrated urine.
Question 4: Which of the following is a common early symptom of chronic kidney disease (CKD)?
- Excessive energy.
- Sudden weight gain.
- Fatigue (Correct answer)
- Increased urine output only at night.
Correct answer: Fatigue
Fatigue is a common early symptom of chronic kidney disease (CKD) due to several contributing factors. As kidney function declines, waste products accumulate, leading to uremia, and patients often develop anemia from decreased erythropoietin production. These combined effects result in a general feeling of tiredness, weakness, and reduced energy levels.
Question 5: How does metabolic acidosis commonly develop in CKD patients?
- Due to increased bicarbonate production.
- Because of excessive vomiting.
- From reduced acid excretion and bicarbonate reabsorption (Correct answer)
- From hyperventilation.
Correct answer: From reduced acid excretion and bicarbonate reabsorption
Metabolic acidosis commonly develops in CKD patients because their impaired kidneys are less able to excrete hydrogen ions (acid) and regenerate or reabsorb bicarbonate. As kidney function declines, the body's buffering capacity is overwhelmed, leading to an accumulation of acid. This imbalance results in a decrease in blood pH, which is characteristic of metabolic acidosis.
Question 6: What is the significance of a decreased glomerular filtration rate (GFR)?
- It indicates improved kidney clearance.
- It reflects normal aging.
- It signifies declining kidney function (Correct answer)
- It suggests increased erythropoietin production.
Correct answer: It signifies declining kidney function
A decreased glomerular filtration rate (GFR) is the most important indicator of declining kidney function. GFR measures how well the kidneys are filtering waste products from the blood. A lower GFR signifies that the kidneys are not effectively removing these waste products, which is a hallmark of chronic kidney disease progression.
Question 7: Which lab value is most useful in assessing renal function?
- Serum potassium.
- Serum creatinine (Correct answer)
- Serum calcium.
- Hemoglobin level.
Correct answer: Serum creatinine
Serum creatinine is the most widely used lab value for assessing renal function because it is a waste product of muscle metabolism primarily filtered by the kidneys. As kidney function declines, creatinine accumulates in the blood, leading to elevated serum levels. This makes it a reliable marker for estimating glomerular filtration rate (GFR) and monitoring kidney health.
Question 8: Why is anemia common in CKD?
- Due to iron overload.
- Because of excessive RBC destruction.
- From decreased erythropoietin production (Correct answer)
- Owing to increased dietary iron intake.
Correct answer: From decreased erythropoietin production
Anemia is very common in chronic kidney disease (CKD) primarily due to decreased production of erythropoietin by the kidneys. Erythropoietin is a hormone essential for stimulating red blood cell production in the bone marrow. With impaired kidney function, insufficient erythropoietin leads to fewer red blood cells, resulting in anemia.
Question 9: How does hyperkalemia occur in CKD patients?
- Due to excessive potassium in the diet alone.
- From reduced potassium excretion by kidneys (Correct answer)
- Because of dehydration.
- Due to high sodium excretion.
Correct answer: From reduced potassium excretion by kidneys
Hyperkalemia, or high potassium levels, frequently occurs in CKD patients because their kidneys lose the ability to adequately excrete potassium. Healthy kidneys efficiently filter and excrete excess potassium, but as kidney function declines, this capacity is severely diminished. This leads to potassium accumulation in the blood, which can be life-threatening.
CSR Renal Physiology & Pathophysiology 1
What is the primary function of the glomerulus in the nephron?