Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

25. The Urinary System

Renal Physiology Step 2: Tubular Reabsorption

Anatomy & Physiology

25. The Urinary System

Renal Physiology Step 2: Tubular Reabsorption

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Problem 7a

Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
a. Sodium ions and glucose are cotransported into the proximal tubule cell by secondary active transport.

Verified step by step guidance

Understand the concept of secondary active transport: Secondary active transport involves the movement of one substance (e.g., sodium ions) down its concentration gradient, which provides the energy to transport another substance (e.g., glucose) against its concentration gradient. This process typically relies on a carrier protein.

Analyze the statement: 'Sodium ions and glucose are cotransported into the proximal tubule cell by secondary active transport.' This suggests that sodium ions and glucose are moved together into the proximal tubule cell using a specific transport mechanism.

Recall the role of the sodium-glucose cotransporter (SGLT): In the proximal tubule of the nephron, sodium ions and glucose are indeed cotransported into the cell by the SGLT protein. Sodium moves down its electrochemical gradient, and this energy is used to transport glucose against its gradient.

Determine if the statement is true or false: Based on the physiological process described, the statement is true because sodium ions and glucose are cotransported into the proximal tubule cell by secondary active transport.

If the statement were false, the correction would involve identifying the incorrect part and revising it. For example, if the statement incorrectly mentioned 'primary active transport,' the correction would be: 'Sodium ions and glucose are cotransported into the proximal tubule cell by secondary active transport.'

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Secondary Active Transport

Secondary active transport is a mechanism that moves ions or molecules across a cell membrane against their concentration gradient, using the energy derived from the movement of another substance down its gradient. This process often involves the coupling of the transport of one substance, like sodium ions, with another, such as glucose, allowing cells to uptake essential nutrients efficiently.

Cotransport

Cotransport refers to the simultaneous transport of two different substances across a cell membrane. In the context of secondary active transport, it typically involves one substance moving down its concentration gradient, which provides the energy needed to transport another substance against its gradient. This is crucial for nutrient absorption in various tissues, including the kidneys.

Proximal Tubule Function

The proximal tubule is a segment of the nephron in the kidney responsible for reabsorbing a significant portion of filtered substances, including glucose and ions. It utilizes mechanisms like secondary active transport to reclaim these vital nutrients from the filtrate back into the bloodstream, playing a key role in maintaining homeostasis and fluid balance in the body.

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Related Practice

Textbook Question

Glucose is not normally found in the urine because it

a. Does not pass through the walls of the glomerulus

b. Is kept in the blood by colloid osmotic pressure

c. Is reabsorbed by the tubule cells

d. Is removed by the body cells before the blood reaches the kidney

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Textbook Question

Which is reabsorbed by the proximal convoluted tubule cells?

a. Na⁺

b. K⁺

c. Amino acids

d. All of the above

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Textbook Question

Two physiology students are having a disagreement about renal function. Dan says that the kidneys work harder when you eat a high-salt diet, whereas Peter says that they work harder when you drink lots of water. Who is right, and why?

Trace the pathway a uric acid molecule takes from a glomerulus to the urethra. Name every gross or microscopic structure it passes through on its journey.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

b. The distal tubule reabsorbs sodium ions and secretes potassium and hydrogen ions in response to ADH.

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Textbook Question

Dilute urine is produced when decreased levels of______ are secreted.

a. Aldosterone

b. Atrial natriuretic peptide

c. ADH

d. None of the above

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Textbook Question

The kidneys produce _____ urine when the osmolarity of the body's fluids increases. They produce _____ urine when the osmolarity of the body's fluids decreases.

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Textbook Question

Trace the pathway taken by a molecule of urea through the kidney from the glomerulus to the renal pelvis if the urea is recycled.

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