40. Circulatory System

Which of the following promotes oxygen release from hemoglobin? a. a decrease in temperature b. an increase in O2 level c. a decrease in pH d. a decrease in carbonic anhydrase activity

When you hold your breath, which of the following blood gas changes first leads to the urge to breathe? a. rising O2 b. falling O2 c. rising CO2 c, falling CO2

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

Frog lungs have a smaller 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. c. Frogs also obtain oxygen via diffusion across the skin. d. Frog lung tissue has a greater density of capillary beds than mammalian lung tissue.

Compared with the interstitial fluid that bathes active muscle cells, blood reaching these cells in arterioles has a a. higher PO2. b. higher PCO2. c. greater bicarbonate concentration. d. lower pH.

Carp are fishes that thrive in stagnant-water habitats with low oxygen partial pressure. Compared with the hemoglobin of many other fish species, carp hemoglobin has an extremely high affinity for O2. Draw an oxygen–hemoglobin equilibrium curve showing separate lines for carp and a fish that lives in water with a higher oxygen partial pressure. Explain why they differ.

During exercise, the cardiovascular system must supply muscles with large amounts of oxygen and fuel and get rid of a lot of wastes. How do the cardiovascular systems of athletes respond to prolonged exercise? 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.

During exercise, the cardiovascular system must supply muscles with large amounts of oxygen and fuel and get rid of a lot of wastes. How do the cardiovascular systems of athletes respond to prolonged exercise? When athletes exercise, what is the primary physiological variable responsible for their sustained increase in ventilation rate? a. decreased blood PO2 b. increased blood PCO2 c. increased blood pH d. increased body temperature