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Ch. 24 The Urinary System
Amerman- Human Anatomy & Physiology 3e
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook
All textbooksAmerman 3rd EditionCh. 24 The Urinary SystemProblem L3.A1c
Chapter 24, Problem L3.A1c

Drugs that treat hypertension, or high blood pressure, have the following actions. Discuss the specific effect that each drug will have on the kidneys.
c. Blocking the Na+/Cl−/2K+ transport pumps in the thick ascending limb of the nephron loop

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Understand the role of the Na+/Cl−/2K+ transport pumps in the thick ascending limb of the nephron loop. These pumps are responsible for reabsorbing sodium (Na+), chloride (Cl−), and potassium (K+) ions from the filtrate back into the bloodstream, which helps maintain the osmotic gradient necessary for water reabsorption in the kidney.
Recognize that blocking these transport pumps will inhibit the reabsorption of Na+, Cl−, and K+ ions. This will disrupt the osmotic gradient in the renal medulla, reducing the kidney's ability to reabsorb water from the filtrate.
Explain that the reduced water reabsorption will lead to an increase in urine output (diuresis). This is because water will remain in the filtrate instead of being reabsorbed into the bloodstream, which can help lower blood volume and, consequently, blood pressure.
Discuss how the increased excretion of Na+ and Cl− ions (natriuresis) will also contribute to a reduction in blood volume. Lower blood volume reduces the workload on the heart and decreases blood pressure.
Conclude that this mechanism makes these drugs effective in treating hypertension by reducing both blood volume and systemic vascular resistance, which are key factors in high blood pressure.

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Key Concepts

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

Nephron Structure and Function

The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. It consists of various segments, including the glomerulus, proximal tubule, loop of Henle, distal tubule, and collecting duct. Each segment plays a specific role in reabsorbing water, electrolytes, and nutrients, as well as excreting waste products.
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Na+/Cl−/2K+ Transport Pumps

The Na+/Cl−/2K+ transport pumps, located in the thick ascending limb of the loop of Henle, are crucial for reabsorbing sodium, chloride, and potassium ions from the filtrate back into the bloodstream. This process is essential for maintaining electrolyte balance and regulating blood pressure. Inhibition of these pumps can lead to increased excretion of these ions and diuresis.
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Effects of Diuretics on Blood Pressure

Diuretics are medications that promote the excretion of water and electrolytes through urine. By blocking the Na+/Cl−/2K+ transport pumps, diuretics reduce sodium reabsorption, leading to decreased blood volume and lower blood pressure. Understanding this mechanism is vital for comprehending how certain antihypertensive drugs function and their impact on kidney function.
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Related Practice
Textbook Question

Mr. Gupta has been diagnosed with nephrotic syndrome, which is characterized by the loss of plasma proteins such as albumin into the urine. What impact will this have on his colloid osmotic pressure? How will this affect the net filtration pressure in his capillary beds? What effect will this likely cause?

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Textbook Question

Explain how each of the drugs in question 1 from this section would lower blood pressure.

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Textbook Question

Deana is a 4-year-old girl with a rare genetic defect that causes the Na+/glucose symporters in the proximal tubule to reabsorb fewer glucose and sodium ions than normal. Predict the effects this defect will have on the composition and volume of Deana's urine. Explain why you would expect to see increased activity of the tubuloglomerular feedback and the renin-angiotensin-aldosterone system in Deana's kidneys.

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Textbook Question

What might it mean if you found a high concentration of urobilinogen in your patient's urine? (Hint: Consider the source of urobilinogen.)

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Textbook Question

Drugs that treat hypertension, or high blood pressure, have the following actions. Discuss the specific effect that each drug will have on the kidneys.

a. Blocking the action of aldosterone on the kidneys

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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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