Chapter 42

In insects, what is the adaptive significance of spiracles? a. They dilate and constrict during flight or other types of movement, functioning as a "breathing" mechanism. b. They open into the body cavity, allowing direct contact between hemolymph and tissues. c. They are thin and highly branched, offering a large surface area for gas exchange. d. They close off tracheae to minimize water loss.

Which of the following is not an advantage of breathing air over breathing water? a. Air is less dense than water, so it takes less energy to move during ventilation. b. Air is less viscous than water, so it takes less energy to move during ventilation. c. The oxygen content of air is greater than that of an equal volume of water d. Air breathing leads to high evaporation rates from the respiratory surface.

Which of the following promotes oxygen release from hemoglobin? a. a decrease in temperature b. a decrease in \(\mathrm{CO}_{2}\) levels c. a decrease in pH d. a decrease in carbonic anhydrase activity

Describe the disadvantages of an open circulatory system relative to a closed circulatory system.

Why is ventilation in birds considered much more efficient than ventilation in humans and other mammals?

Explain how each parameter in Fick's law of diffusion is reflected in the structure of the mammalian lung.

Carp are fishes that thrive in stagnant-water habitats with low oxygen partial pressures. Compared with the hemoglobin of many other fish species, carp hemoglobin has an extremely high affinity for \(\mathrm{O}_{2}\). Is this trait adaptive? Explain your answer.

Frog lungs have a lower surface area for gas exchange than mammalian lungs. How do frogs compensate for this difference? a. Frog tissue absorbs more oxygen from the blood than mammalian tissue does. b. Frogs breathe more quickly than mammals. e. Frogs also obtain oxygen via diffusion across the skin. d. Frog lung tissue has a greater density of capillary beds than mammalian lung tissue.

Predict how Antarctic icefish can transport enough oxygen in their blood to meet their needs even though they lack hemoglobin.

Why did separate systemic and pulmonary circulations evolve in species that have the high-pressure circulatory system required for rapid movement of blood?

During athletic training, the oxygen-hemoglobin dissociation curve a. shifts to the right, unloading more oxygen to tissues. b. shifts to the right, unloading less oxygen to tissues. c. shifts to the left, unloading more oxygen to tissues. d. shifts to the left, unloading less oxygen to tissues.

When athletes exercise, what is the primary physiological variable responsible for their sustained increase in ventilation rate? a. decreased blood \(P_{0_{2}}\) b. increased blood \(P_{\mathrm{CO}_{2}}\) c. increased blood pH d. increased body temperature

Researchers have also observed that athletes and non-athletes have the same mean resting cardiac output, even though athletes have a far lower resting heart rate. How is this possible?

Athletes are not the only people with enlarged hearts. Many patients with cardiovascular disease also have enlarged hearts. Suggest a cause of this enlargement.