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