1. Relate the three primary nitrogenous wastes to the habitat of animals.

•Ammonia~ Very toxic. Can be eliminated from the body IF the organism lives in water, and has structures that are in direct contact with water all the time.•Urea~ Less toxic and can be accumulated in the body. Requires a lot of energy to be made from ammonia. Important for land animals so they can conserve body water.•Uric acid~ Least toxic. Not soluble in water. Very important for water conservation. Allows animals to develop inside of eggs w/o toxic wastes building up and killing the developing animal.

2. Describe how the excretory organs of the earthworm and the insect function.

•Earthworm~ (Ammonia and water) two “neprhidia” in each body segment. Wastes and move through here and are excreted through a pore. 60% of body weight is excreted each day.

•Insect~ Uric acid “Malpighian tubules,” long thin tubules attached to gut. Active transport of Uric acid into tubes. Water moves into tubes and must be reabsorbed later.

3. Contrast the osmotic regulation of a marine bony fish with a freshwater bony fish.

Marine fish~ Urine in small amounts. Constantly drinking seawater (loss through osmosis). Salts are excreted through active transport).

Freshwater fish~ Very dilute urine in massive amounts. Water is constantly diffusing into cells. Salt is actively moved to blood.

4. Give examples of how other animals regulate their water and salt balance.

•Kangaroo rat~ Lives in arid environment and must conserve water:

–Fur–Inactive during the day–Maze-like nasal passageways that collect condensation in breath.–Very concentrated urine–Dry feces–Obtains water through reactions in cell respiration (does not drink!!)

•Sea animals~ Drink salt water. –Whales~ enormous kidneys –Birds~ Have special glands on the beak that pump salt from the blood.–Sea turtles~ specialized tear ducts/ glands for pumping salt–Sea snakes~ specialized glands below the tongue that pump salt

5. Describe the path of urine in humans and give a function for each structure mentioned.

•Kidney- Filtration of blood, formation of urine reabsorption of necessary products back to blood.

•Ureter- Tube connecting the kidney to bladder.

•Bladder- Temporary storage of urine.

•Urethra- Tube connecting bladder to outside environment.

6. Describe the macroscopic anatomy of a human kidney and relate it to the placement of nephrons.

Cortex- Less concentrated tissues (less solutes). Most of the nephron is found in this region

Medulla- More concentrated tissues (more solutes). Only the loop of the nephron is found in this region.

7. List the parts of a nephron and give a function for each structure mentioned.

•Glomerulus- blood plasma is pushed from the blood here. (filtration)•Glomerular (Bowman’s capsule)- blood plasma from the glomerulus is collected here•Convoluted tubule (renal tubule)- Components of urine remain in this tube, materials needed by the blood are pushed out and recaptured by the capillaries.•Capillaries- Make a “ball” in glomerulus. Form a network around the renal tubule to recapture important blood componenents.•Loop of the nephron (Henle) Part of nephron that dips into the medulla. Helps to move materials in or out of the nephron and into the blood.•Collecting duct Moves some materials from the blood to urine. (H+ especially)

8. Describe how urine is made by outlining what happens at each part of the nephron.

•Glomerulus- plasma is “filtered” out of the blood.•Glom. Capsule- plasma from blood enters the renal tubule.•Renal tubule- Materials that must be moved back to the blood are transported from the tubule to capillaries.•Collecting duct- H+ ions are moved to adjust the pH of the blood.

9. Describe the reabsorption of water and salt along the length of the nephron. Include the contribution of the loop of the nephron (Henle)

•As the nephron goes deeper into the kidney the concentration of solutes get more concentrated.•This forces water out of the renal tubule•This also happens in the collecting tubule.•Hormones regulate the uptake of water by the bloodstream

10. Name and describe the action of antidiuretic hormone (ADH), the renin-aldosterone connection and the atrial natriuretic hormone (ANH).

•ADH~ Makes the collecting tubule more permeable to water. (We retain more water this way)

•Renin-aldosterone connex~ renin stim’s angiotension (from liver) stim’s aldosterone (from adrenals) causes ions to move and water to be reabsorbed by the blood

•ANH~ counteracts renin (above) & stimulates the release of Na+ and water)

11. How does the nephron regulate the pH of the blood?

•Related to breathing (co2 is carried as carbonic acid in the blood)•The kidneys can release H+ ions or HCO3 ions (bicabonate) to adjust pH as needed