Multiple Choice
Where does most nutrient reabsorption occur in the nephron?
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25. The Urinary System
Renal Physiology Step 2: Tubular Reabsorption
Problem 3
Textbook Question
The process of urine formation involves all of the following, except
(a) Filtration of plasma
(b) Reabsorption of water
(c) Reabsorption of certain solutes
(d) Secretion of wastes
(e) Secretion of excess lipoprotein and glucose molecules
Verified step by step guidance1
Step 1: Understand the process of urine formation, which primarily involves three key stages: filtration, reabsorption, and secretion. Filtration occurs in the glomerulus where plasma is filtered to form filtrate.
Step 2: Recognize that reabsorption involves the movement of water and certain solutes from the filtrate back into the bloodstream, helping to conserve essential substances and maintain fluid balance.
Step 3: Identify that secretion is the active transport of additional wastes and excess ions from the blood into the tubular fluid to be excreted in urine.
Step 4: Analyze each option in the problem: (a) filtration of plasma, (b) reabsorption of water, (c) reabsorption of certain solutes, and (d) secretion of wastes are all normal parts of urine formation.
Step 5: Note that (e) secretion of excess lipoprotein and glucose molecules is not a typical part of urine formation because lipoproteins are generally not secreted into urine, and glucose is usually reabsorbed completely unless in pathological conditions like diabetes.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Filtration of Plasma
Filtration is the first step in urine formation where blood plasma is filtered through the glomerulus into Bowman's capsule, allowing water and small solutes to pass while retaining blood cells and large proteins.
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The Filtration Membane
Reabsorption of Water and Solutes
Reabsorption occurs mainly in the renal tubules, where essential substances like water, glucose, and ions are selectively reabsorbed back into the bloodstream to maintain homeostasis.
Recommended video:
2:301b) Passive Reabsorption of Water & Solutes in the Proximal Tubule
Secretion of Wastes
Secretion is the active transport of additional waste substances and excess ions from the blood into the tubular fluid, helping to eliminate toxins and maintain chemical balance in the body.
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01:33Protein Secretion
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