Chapter 48

Which of the following statements about osmoregulation is true? a. In freshwater invertebrates, salts move out of the body into the water because the animal is hypoosmotic to the water. b. A marine teleost has to fight gaining water because it is isoosmotic to the sea. c. Most land animals are osmoconformers. d. Vertebrates are usually osmoregulators. e. Terrestrial animals can regulate their osmolarity without expending energy.

One role of tubules in excretion is to: a. absorb \(\mathrm{H}^{+}\) ions to buffer body fluids. b. transport proteins across the transport epithelium. c. reabsorb glucose and amino acids. d. move toxic substances from the filtrate into the cells composing the transport tubules. e. filter by maintaining a lower pressure in the fluid outside the tubule than inside it.

Which of the following correctly describes a part of kidney function? a. Collecting ducts dilute urine because they are permeable to salt but not water. b. In the ascending loop of Henle, \(\mathrm{Na}^{+}\) and \(\mathrm{Cl}^{-}\) move into the tubules because the osmolarity of the filtrate is increased. c. The descending loop of Henle receives filtrate from the ascending loop. d. The distal convoluted tubule pumps water into the tubule by active transport. e. The renal pelvis receives urine from the collecting ducts and carries it to the ureters.

Which of the following is an example of autoregulation of kidney function? a. The RAAS regulates Na \(^{+}\) by secreting renin when blood pressure or blood volume decreases. b. The ADH system regulates water balance by decreasing water reabsorption and increasing excretion of salt. c. Receptors in the juxtaglomerular apparatus detect a higher salt concentration in the distal convoluted tubule and trigger constriction of the afferent arteriole to reduce glomerular filtration rate. d. ANF is released by the kidney to increase renin release. e. Angiotensin II lowers blood pressure by constricting arterioles.

Deficient water levels in humans are prevented by: a. osmoreceptors in the hypothalamus that detect decreases in salt concentrations. b. the hypothalamus stimulating the posterior pituitary to secrete a hormone that allows the collecting ducts and distal convoluted tubules to be permeable to water. c. inhibiting ADH, which causes a rise in osmolarity of the ECF. d. producing dilute urine. e. drinking alcohol, which stimulates aldosterone to raise the osmolarity of body fluids.

Which best exemplifies ectothermy? a. The metabolic rate increases as the temperature decreases. b. Body temperature remains constant when environmental temperatures change. c. Food demand increases when temperatures drop. d. Virtually all invertebrate groups are ectotherms. e. No vertebrate groups are ectotherms.

Unique to endotherms is: a. torpor. b. thermal acclimatization. c. a nonchanging body temperature. d. response to seasonal temperature changes. e. thermoregulation by a hypothalamus.

A urinalysis reveals glucose, urea, hemoglobin, and sodium. Which of these substances are abnormal in urine, and why?

As a person ages, nephron tubules lose some of their ability to concentrate urine. What is the effect of this change?

Shivering increases air movement over the body surface. What effect does this air movement have on heat conservation in the shivering animal?

What heat transfer processes might account for the change in body temperature when a mammal's body temperature undergoes daily variations?

Humans produce urea as an excretion product, whereas reptiles and birds produce uric acid. Indeed, human kidneys are not as efficient as those of reptiles and birds. What does this mean in an evolutionary sense?