Human Anatomy and Physiology : Help with Nephron Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

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Example Question #851 : Human Anatomy And Physiology

What is the main purpose of the vasa recta?

Possible Answers:

Provides the nephron with oxygen-rich blood

Reabsorbs the majority of the solute from the filtrate

Secretes the majority of the  and  ions into the filtrate

Maintains countercurrent multiplication to prevent disregulation in the concentration gradients set up in the renal medulla

Maintains appropriate temperature in the renal medulla to allow for regular blood flow

Correct answer:

Maintains countercurrent multiplication to prevent disregulation in the concentration gradients set up in the renal medulla

Explanation:

The vasa recta wind around the loop of Henle and maintain a countercurrent multiplication to prevent any disregulation or washout of the concentration gradient that has been set up in the renal medulla.  Without this gradient, the nephron would be unable to concentrate filtrate.  Since the vasa recta carry venous blood, it's oxygen concentration is low and thus needs to go through the pulmonary circuit to pick up more oxygen.

Example Question #851 : Human Anatomy And Physiology

Which of the following is the most concentrated part of the nephron?

Possible Answers:

Collecting duct

Distal convoluted tubule

Thick ascending loop of Henle

Thin descending loop of Henle

Proximal convoluted tublue

Correct answer:

Thin descending loop of Henle

Explanation:

Thin descending loop of Henle is the most concentrated part of the nephron. As you progress up and down the nephron, the closer the nephron is to the medulla, the more concentrated it is. This ability is due to the increases absorption of water and the inability to reabsorb solute at this level. 

The other mentioned parts of the nephron are permeable to solute and some water and thus are not as concentrated as the thin descending loop of Henle.

Example Question #853 : Human Anatomy And Physiology

If the efferent arteriole becomes constricted, what is likely to occur in the nephron? 

Possible Answers:

Glomerular filtration rate will remain the same

The increased hydrostatic pressure will elevate glomerular filtration rate

Fluid backup will cause the nephron to rupture

Glomerular filtration rate will decrease due to a loss in blood pressure

The increased osmotic pressure will elevate glomerular filtration rate

Correct answer:

The increased hydrostatic pressure will elevate glomerular filtration rate

Explanation:

The efferent arteriole carries blood away from the glomerulus, and so if it is constricted, the blood pressure behind it will increase.  The raise in blood pressure will result in an increase in hydrostatic pressure, pushing additional fluid through the glomerulus i.e elevated glomerular filtration rate. While high hydrostatic pressure does cause damage to the nephron, the nephron rupturing is too extreme of a statement and requires assumptions that are not necessarily valid.

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