Chapter 11 | Osmotic Regulation and Excretion

  1. Figure 11.5 Which of the following statements about the kidney is false?
    1. The renal pelvis drains into the ureter.
    2. The renal pyramids are in the medulla.
    3. The cortex covers the capsule.
    4. Nephrons are in the renal cortex. 
      The kidney is shaped like a kidney bean standing on end. Two layers, the outer renal fascia and an inner capsule, cover the outside of the kidney. The inside of the kidney consists of three layers: the outer cortex, the middle medulla and the inner renal pelvis. The renal pelvis is flush with the concave side of the kidney, and empties into the ureter, a tube that runs down outside the concave side of the kidney. Nine renal pyramids are embedded in the medulla, which is the thickest kidney layer. Each renal pyramid is teardrop-shaped, with the narrow end facing the renal pelvis. The renal artery and renal vein enter the concave part of the kidney, just above the ureter. The renal artery and renal vein branch into arterioles and venuoles, respectively, which extend into the kidney and branch into capillaries in the cortex.
      Figure 11.5 The internal structure of the kidney is shown. (credit: modification of work by NCI)
  2. Figure 11.6 Which of the following statements about the nephron is false?
    1. The collecting duct empties into the distal convoluted tubule.
    2. The Bowman’s capsule surrounds the glomerulus.
    3. The loop of Henle is between the proximal and distal convoluted tubules.
    4. The loop of Henle empties into the distal convoluted tubule. 
      Illustration shows the nephron, a tube-like structure that begins in the kidney cortex. Here, arterioles converge in a bulb-like structure called the glomerulus, which is partly surrounded by a Bowmans capsule. Afferent arterioles enter the glomerulus, and efferent arterioles leave. The glomerulus empties into the proximal convoluted tubule. A long loop, called the loop of Henle, extends from the proximal convoluted tubule to the inner medulla of the kidney, and then back out to the cortex. There, the loop of Henle joins a distal convoluted tubule. The distal convoluted tubule joins a collecting duct, which travels from the medulla back into the cortex, toward the center of the kidney. Eventually, the contents of the renal pyramid empty into the renal pelvis, and then the ureter.
      Figure 11.6 The nephron is the functional unit of the kidney. The glomerulus and convoluted tubules are located in the kidney cortex, while collecting ducts are located in the pyramids of the medulla. (credit: modification of work by NIDDK)
  3. Figure 11.8 Loop diuretics are drugs sometimes used to treat hypertension. These drugs inhibit the reabsorption of Na+ and Cl- ions by the ascending limb of the loop of Henle. A side effect is that they increase urination. Why do you think this is the case? 
    A U-shaped tube represents the loop of Henle. Filtrate enters the descending limb, and exits the ascending limb. The descending limb is water-permeable, and water travels from the limb to the interstitial space. As a consequence, the osmolality of the filtrate inside the limb increases from 300 milliosmoles per liter at the top to 1200 milliosmoles per liter at the bottom. The ascending limb is permeable to sodium and chloride ions. Because the osmolality inside bottom part of the limb is higher than the interstitial fluid, these ions diffuse out of the ascending limb. Higher up, sodium is actively transported out of the limb, and chloride follows. At the top of the ascending limb, the filtrate is 100 milliosmoles.
    Figure 11.8 The loop of Henle acts as a countercurrent multiplier that uses energy to create concentration gradients. The descending limb is water permeable. Water flows from the filtrate to the interstitial fluid, so osmolality inside the limb increases as it descends into the renal medulla. At the bottom, the osmolality is higher inside the loop than in the interstitial fluid. Thus, as filtrate enters the ascending limb, Na+ and Cl- ions exit through ion channels present in the cell membrane. Further up, Na+ is actively transported out of the filtrate and Cl- follows. Osmolarity is given in units of milliosmoles per liter (mOsm/L).

License

Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

Human Biology Copyright © by Janet Wang-Lee is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Share This Book