In this schematic of urine production in a nephron, label the four processes involved and list some of the substances that are moved in each process.

Unlike an earthworm's metanephridia, a mammalian nephron

a. Is intimately associated with a capillary network.

b. Functions in both osmoregulation and excretion.

c. Receives filtrate from blood instead of coelomic fluid.

d. Has a transport epithelium.

Which of the following statements regarding fishes that live in fresh-water is/are correct? Select True or False for each statement.

T/F Water moves across the gills via osmosis until equilibrium is established, at which time the water molecules stop moving.

T/F They lose water to their environment primarily through the gills. They replace this water by drinking.

T/F Water enters epithelial cells in their gills via osmosis. Electrolytes leave the same cells via diffusion.

T/F They have specialized epithelia that actively pump electrolytes from the environment into the blood.

Which process in the nephron is least selective?

a. Filtration

b. Reabsorption

c. Active transport

d. Secretion

Which of the following organisms would lose the most water by osmosis across its gills?

a. Marine bony fish

b. Shark

c. Freshwater fish

d. Freshwater invertebrate

Which of the following animals generally has the lowest volume of urine production?

a. Vampire bat

b. Salmon in fresh water

c. Marine bony fish

d. Freshwater flatworm

What effect does antidiuretic hormone (ADH) have on the nephron?

a. It increases the water permeability of the descending limb of the loop of Henle.

b. It decreases the water permeability of the descending limb of the loop of Henle.

c. It increases the water permeability of the collecting duct.

d. It decreases the water permeability of the collecting duct.

The high osmolarity of the renal medulla is maintained by which of the following?

a. Active transport of salt from the upper region of the descending limb.

b. The loose packing of juxtamedullary nephrons.

c. Diffusion of urea into the collecting duct.

d. Diffusion of salt from the descending limb of the loop of Henle.