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Questions and Answers
What is the term used for the process of filtering blood in the kidney?
Which molecules are primarily included in the glomerular filtrate?
Where does most selective reabsorption of molecules occur in the nephron?
What percentage of water is typically reabsorbed in the proximal convoluted tubule?
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Which hormone facilitates sodium reabsorption in the kidney?
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What happens to glucose in the urine of a healthy person?
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How much urine is typically produced by the kidneys in 24 hours under normal conditions?
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What is the primary mechanism of water reabsorption in the nephron?
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Study Notes
Glomerular Filtration
- Urine is produced by filtering waste and fluids from the blood in the kidneys.
- The initial filtration occurs in the glomerulus through a process known as ultra-filtration.
- Glomerular filtrate primarily contains water, electrolytes, amino acids, bicarbonate, and nitrogenous wastes like urea, uric acid, and creatinine.
- Glomerular filtration rate (GFR) is influenced by hydrostatic pressure in the glomerulus, which is affected by the diameter difference of afferent and efferent arterioles.
- The kidney filters approximately 180 liters of blood daily, resulting in the production of 2.5 liters of urine under normal conditions.
- GFR is typically stable due to autoregulation, but can vary with changes in fluid intake or body fluid levels.
Selective Reabsorption
- The composition of glomerular filtrate differs from that of urine, indicating changes as fluid moves through the renal tubules (PCT, loop of Henle, DCT).
- For a healthy person, glucose is reabsorbed from the filtrate and is not found in urine, while urea and uric acid levels are higher in urine than in filtrate.
- Selective reabsorption allows for the recovery of specific molecules filtered out of blood, including nitrogenous wastes and water.
- Most selective reabsorption occurs in the proximal convoluted tubule (PCT), where vital substances are returned to the bloodstream.
- Around 67% of water, 100% of glucose, along with various electrolytes (Na, K, Cl, Ca, Mg, HPO42-) and nutrients are reabsorbed in the PCT.
- Water reabsorption is passive, while glucose and sodium reabsorption is active.
- Sodium aids in the reabsorption of negatively charged ions through charge interactions.
- Aldosterone hormone enhances sodium reabsorption, while antidiuretic hormone (ADH) promotes water reabsorption.
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Description
Test your understanding of the glomerular filtration process in the kidneys. This quiz covers the initiation of urine formation, the composition of glomerular filtrate, and the mechanisms involved in ultra-filtration. Dive into the fascinating biology behind kidney function and waste removal.
