Renal Physiology & Pathophysiology Flashcards

What is the primary function of the glomerulus in the nephron?

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.

Which hormone is most directly involved in sodium reabsorption in the distal nephron?

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.

What is the role of the loop of Henle in urine concentration?

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.

Which of the following is a common early symptom of chronic kidney disease (CKD)?

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.

How does metabolic acidosis commonly develop in CKD patients?

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.

What is the significance of a decreased glomerular filtration rate (GFR)?

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.

Which lab value is most useful in assessing renal function?

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.

Why is anemia common in CKD?

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.

How does hyperkalemia occur in CKD patients?

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.