Major organs of the excretory system:

The Nephron: the functional unit of a kidney

• filtration
• resorption
• secretion
• concentration gradient
• importance of active transport, diffusion, osmosis

QUESTIONS:

1. The organ that filters metabolic wastes out of the blood is called the ______________.  This organ is made of about a million functional units called _________________.  The fluid produced by this organ is called ________________.  The fluid moves from this organ through a tube called the _______________; this tube takes the fluid to another organ, the _______________ for storage.  When this fluid is lost from the body, it leaves through a tube called the ___________________.
2.  Draw a nephron.  Label & describe the function of each of the following parts of the nephron: the glomerulus, Bowman's capsule, the proximal and distal convoluted tubules, the loop of Henle, the collecting duct.
3.  How does fluid from blood get from the circulatory system into the nephron?
4.  The movement of fluid from the glomerulus into Bowman's Capsule is called ___________________.
5. When fluid is in the proximal and distal convoluted tubules, substances from the fluid are actively transported into the blood.  This process is called ____________________.  Explain why this process is important to body function.
6.  When fluid is in the proximal and distal convoluted tubules, substances from blood vessels surrounding these tubules are actively transported into the fluid in the tubules.  This process is called ___________________.  Explain why this process is important to body function.
7.  Which structures in the nephron are involved in producing concentrated urine and regulating water balance?
8.  Do ions move in or out of the descending limb of the loop of Henle?  Do ions move in or out of the ascending limb of the loop of Henle?  Which ions are moved by active transport and which by diffusion?  What is the effect of  the loop of Henle on each of the following:
   a. the concentration of solutes in the fluid in the distal convoluted tubule
   b. the concentration of solutes in the fluid around the bottom of the loop of Henle
   c. the concentration of solutes around the top of the loop of Henle
   d. the concentration difference between the inside and outside of the collecting duct
9.  Why does fluid move out of the collecting duct?  What is the result of this on urine concentration?
10.  How is the process of osmosis important in determining the solute concentration of urine?