Human Anatomy and Physiology : Help with Nephron Physiology
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Example Question #11 : Help With Nephron Physiology
What is the main purpose of the vasa recta?
Maintains appropriate temperature in the renal medulla to allow for regular blood flow
Reabsorbs the majority of the solute from the filtrate
Maintains countercurrent multiplication to prevent disregulation in the concentration gradients set up in the renal medulla
Secretes the majority of the 
Provides the nephron with oxygen-rich blood
Maintains countercurrent multiplication to prevent disregulation in the concentration gradients set up in the renal medulla
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 #12 : Help With Nephron Physiology
Which of the following is the most concentrated part of the nephron?
Thin descending loop of Henle
Thick ascending loop of Henle
Distal convoluted tubule
Proximal convoluted tublue
Collecting duct
Thin descending loop of Henle
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 #13 : Help With Nephron Physiology
If the efferent arteriole becomes constricted, what is likely to occur in the nephron?
Fluid backup will cause the nephron to rupture
Glomerular filtration rate will remain the same
Glomerular filtration rate will decrease due to a loss in blood pressure
The increased osmotic pressure will elevate glomerular filtration rate
The increased hydrostatic pressure will elevate glomerular filtration rate
The increased hydrostatic pressure will elevate glomerular filtration rate
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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