42. Osmoregulation and Excretion

An albatross spending its life hovering over the ocean provides an extreme example of __________, the process by which animals control solute concentrations and balance water gain and loss.

Osmoconformers are animals that __________.

In a marine environment, animals that are isoosmotic relative to their environment __________.

Which type of organism would have the least chance of long-term survival in the given environment?

Why do freshwater fish excrete a large amount of very dilute urine?

Dehydration in animals __________.

How do aquatic birds such as the wandering albatross avoid becoming dehydrated even though they live in an environment that is almost entirely salt water?

Most of our nitrogen-containing waste products are a result of __________.

What conditions are responsible for the stimulation of the juxtaglomerular apparatus (JGA)?

Alcohol consumption increases urinary output because alcohol __________.

Secretion of ADH (antidiuretic hormone) from the __________ occurs in response to __________ and causes __________.

Most aquatic animals excrete ammonia, whereas land animals excrete urea or uric acid. What is the most likely explanation for this difference?

What is the function of antidiuretic hormone (ADH) in the body?

The loops of Henle in the kidneys of a desert kangaroo rat are much longer than those in a white laboratory rat because the __________.

At a particular position along a nephron, the osmotic potential of the filtrate is 500 mOsm/L, whereas the surrounding kidney's is 600 mOsm/L. Which of the following is a likely result?

The lowest osmotic potential inside a nephron will be found in __________.

What is the function of the ascending loop of Henle?

As filtrate passes through the long loop of Henle, salt is removed and concentrated in the interstitial fluid of the kidney medulla. Because of this high salt concentration, the nephron is able to __________.

All of the following processes occur in the nephron of the kidney except __________.

Which is an accurate pairing of a key excretory function with its definition?

Which is an accurate statement about the anatomy of the human excretory system?

Which of the following substances is generally filtered from the blood by the kidneys?

The primary nitrogen-containing compound excreted by our kidneys is __________.

Metanephridia are found in __________ and function in __________.

The fluid that enters vertebrate nephrons is called the filtrate. What is the source of the filtrate?

The most effective molecule for nitrogenous waste disposal in desert animals would be __________.

Many insects, birds, and other reptiles excrete nitrogenous wastes in the form of uric acid, which __________.

In each nephron of the kidney, the glomerulus and Bowman's capsule __________.

The bed of capillaries in a vertebrate kidney where water, urea, and salts are filtered out of the blood is the __________.

Which of the following is a function of the excretory system?

Which excretory system contains structures called flame bulbs that function in filtration?

Which of the following is filtered from blood but not normally found in urine?

The filtrate formed by the nephrons in the kidney is not urine. The filtrate is first refined and concentrated by the processes of __________, which form the urine that leaves the body.

Which of the following is the most accurate and comprehensive description of the function of kidneys?

The functional units of kidneys are __________.

Which of the following is a tube that carries urine from the kidneys to the urinary bladder in a mammal?

Complete this map, which presents the three main topics of this chapter.

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.

The high osmolarity of the renal medulla is maintained by all of the following except a. active transport of salt from the upper region of the ascending limb. b. the spatial arrangement of juxtamedullary nephrons. c. diffusion of urea from the collecting duct. d. diffusion of salt from the descending limb of the loop of Henle.

In each nephron of the kidney, the glomerulus and Bowman's capsule a. filter the blood and capture the filtrate. b. reabsorb water into the blood. c. break down harmful toxins and poisons. d. refine and concentrate the urine for excretion.

Birds and insects excrete uric acid, whereas mammals and most amphibians excrete mainly urea. What is the chief advantage of uric acid over urea as a waste product? a. Uric acid is a much simpler molecule. b. It takes less energy to make uric acid. c. Less water is required to excrete uric acid. d. More solutes are removed excreting uric acid.

A freshwater fish would be expected to a. pump salt out through its gills. b. produce copious quantities of dilute urine. c. have scales and a covering of mucus that reduce water loss to the environment. d. do all of the above.

Match each of the following components of blood (on the left) with what happens to it as the blood is processed by the kidney (on the right). Note that each lettered choice may be used more than once. 8. Water 9. Glucose 10. Plasma protein 11. Toxins or drugs 12. Red blood cell 13. Urea a. passes into filtrate; almost all excreted in urine b. remains in blood c. passes into filtrate; mostly reabsorbed d. secreted and excreted

Which process in the nephron is least selective? a. secretion b. reabsorption c. filtration d. passive diffusion of salt

Compare the water and salt regulation in a salmon when it swims in the ocean to when it migrates into fresh water to spawn.

Two endothermic animals are the same size, but one is a carnivore and the other is an herbivore. Predict which of these animals would produce the greatest amount of nitrogenous wastes. Explain.

Kidneys were the first organs to be transplanted successfully. A donor can live a normal life with a single kidney, making it possible for individuals to donate a kidney to an ailing relative or even an unrelated individual. In some countries, poor people sell kidneys to transplant recipients through organ brokers. What are the pros and cons associated with organ commerce?

Scientists have found that the quantity of aquaporin molecules inserted in the membranes of collecting duct cells changes in response to ADH levels. Draw a line graph proposing a relationship between ADH levels and its effect on the quantity of aquaporins. Additionally, explain how the relationship between ADH and aquaporins corresponds to situations of dehydration and hydration.