Chapter 42

Atmospheric pressure at sea level is equal to a column of 760 mm Hg. Oxygen makes up 21 percent of the atmosphere by volume. The partial pressure of oxygen ( ) in such conditions is _____. A) 160 mm Hg B) 16 mm Hg C) 21/760 D) 760/21

A) 160 mm Hg

You are a physician, and you are seeing a patient who complains of abnormal fatigue during exercise. You find that the immediate problem is a buildup of carbon dioxide in the tissues. What is the most likely cause? A) abnormally shaped platelets B) abnormal carbonic anhydrase C) abnormal hemoglobin D) not enough hemoglobin

B) abnormal carbonic anhydrase

At the summit of a high mountain, the atmospheric pressure is 380 mm Hg. If the atmosphere is still composed of 21percent oxygen, then the partial pressure of oxygen at this altitude is about _____. A) 80 mm Hg B) 160 mm Hg C) 380 mm Hg D) 760 mm Hg

A) 80 mm Hg

You cut your finger, and after putting pressure on the wound for several minutes, you notice that it is still bleeding profusely. What may be the problem? A) Platelets are not functioning properly, or there are too few to be effective. B) Mast cells are not releasing their chemical messengers. C) There are too many antigens to allow clotting. D) Hemoglobin levels are too high to allow clotting.

A) Platelets are not functioning properly, or there are too few to be effective.

An oil-water mixture works as an insecticidal spray against mosquitoes and other insects because it _____. A) blocks the openings into the tracheal system B) interferes with gas exchange across the capillaries C) clogs their bronchi D) prevents gases from leaving the atmosphere

A) blocks the openings into the tracheal system

Most of the carbon dioxide produced by humans is _____. A) converted to bicarbonate ions by an enzyme in red blood cells B) bound to hemoglobin C) transported in the erythrocytes as carbonic acid D) simply dissolved in the plasma

A) converted to bicarbonate ions by an enzyme in red blood cells

Under identical atmospheric conditions, freshwater _____. A) has more oxygen than seawater B) has less oxygen than seawater C) can hold 10-40 times more carbon dioxide than air D) can hold 10-40 times more oxygen than air

A) has more oxygen than seawater

Compared with the interstitial fluid that bathes active muscle cells, blood reaching these muscle cells in arteries has a _____. A) higher po2 B) greater bicarbonate concentration C) lower pH D) lower osmotic pressure

A) higher po2

What would be the consequences if we were to reverse the direction of water flow over the gills of a fish, moving water inward past the operculum, past the gills, the out the mouth? This reversal of water flow would _____. A) reduce efficiency of gas exchange B) change the exchange of gases in the body from carbon dioxide out and oxygen in to carbon dioxide in and oxygen out C) increase the efficiency of gas exchange

A) reduce efficiency of gas exchange

Countercurrent exchange is evident in the flow of _____. A) water across the gills of a fish and the blood within those gills B) blood in the dorsal vessel of an insect and that of air within its tracheae C) air within the primary bronchi of a human and the blood within the pulmonary veins D) water across the skin of a frog and the blood flow within the ventricle of its heart

A) water across the gills of a fish and the blood within those gills

The sun shining on a tidal pool during a hot day heats the water. As some water evaporates, the pool becomes saltier, causing _____. A) an increase in its carbon dioxide content B) a decrease in its oxygen content C) an increase in its ability to sustain aerobic organisms D) a decrease in the water's density

B) a decrease in its oxygen content

The hormone that stimulates the production of red blood cells, and the organ where this hormone is synthesized, are _____. A) growth hormone and pancreas, respectively B) erythropoietin and kidney, respectively C) cortisol and adrenal gland, respectively D) acetylcholine and bone marrow, respectively

B) erythropoietin and kidney, respectively

Carbon dioxide levels in the blood and cerebrospinal fluid affect pH. This enables the organism to sense a disturbance in gas levels as _____. A) the brain directly measures and monitors oxygen levels and causes breathing changes accordingly B) the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this measure to control breathing C) the brain alters the pH of the cerebrospinal fluid to force the animal to retain more or less carbon dioxide D) stretch receptors in the lungs cause the medulla oblongata to speed up or slow breathing

B) the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this measure to control breathing

Carbonic anhydrase inhibitors cause less movement of carbonic acid toward carbon dioxide production and are used as a prophylactic treatment of altitude sickness. Altitude sickness occurs when a hiker ascends to altitudes where the density of oxygen is low. How does this decrease the symptoms of high altitude sickness? A) The excess hydrogen ions are excreted in the urine and the resulting loss of acidity increases respiration rate. B) The excess bicarbonate ions are excreted in the urine and the resulting loss of blood pressure increases respiration rate. C) The excess bicarbonate ions are excreted in the urine and the resulting increase in blood acidity leads to an increase in ventilation. D) The excess bicarbonate ions in the blood increase the affinity of hemoglobin for oxygen.

C) The excess bicarbonate ions are excreted in the urine and the resulting increase in blood acidity leads to an increase in ventilation.

Which of the following statements comparing respiration in fish and in mammals is correct? A) The respiratory medium for fish carries more oxygen than the respiratory medium of mammals. B) A countercurrent exchange mechanism between the respiratory medium and blood flow is seen in mammals but not in fish. C) The movement of the respiratory medium in mammals is bidirectional, but in fish it is unidirectional. D) In blood, oxygen is primarily transported by plasma in fish, but by red blood cells in mammals.

C) The movement of the respiratory medium in mammals is bidirectional, but in fish it is unidirectional.

A rabbit taken from a meadow near sea level and moved to a meadow high on a mountainside would have some trouble breathing. Why? A) The percentage of oxygen in the air at high elevations is lower than at sea level. B) The percentage of oxygen in the air at high elevations is higher than at sea level. C) The partial pressure of oxygen in the air at high elevations is lower than at sea level. D) The partial pressure of oxygen in the air at high elevations is higher than at sea level.

C) The partial pressure of oxygen in the air at high elevations is lower than at sea level.

A normal event in the process of blood clotting is the _____. A) production of erythropoietin B) conversion of fibrin to fibrinogen C) activation of prothrombin to thrombin D) synthesis of hemoglobin

C) activation of prothrombin to thrombin

During most daily activities, the human respiration rate is most closely linked to the blood levels of _____. A) nitrogen B) oxygen C) carbon dioxide D) carbon monoxide

C) carbon dioxide

An decrease from pH 7.4 to pH 7.2 causes hemoglobin to _____. A) release all bound carbon dioxide molecules B) bind more oxygen molecules C) increase its binding of H+ D) give up more of its oxygen molecules

C) increase its binding of H+

Some human infants, especially those born prematurely, suffer serious respiratory failure because of _____. A) the sudden change from the uterine environment to the air B) the overproduction of surfactants C) lung collapse due to inadequate production of surfactant D) mutations in the genes involved in lung formation

C) lung collapse due to inadequate production of surfactant

Flying insects typically _____. A) decrease metabolism as much as 200-fold during flight B) switch from diffusion of tracheal gases to active transport during flight C) utilize high numbers of mitochondria in flight muscles D) generate fuel molecules from catabolism of carbon dioxide

C) utilize high numbers of mitochondria in flight muscles

A person with a tidal volume of 450 mL (milliliters), a vital capacity of 4000 mL, and a residual volume of 1000 mL would have a potential total lung capacity of _____. A) 1450 mL B) 4000 mL C) 4450 mL D) 5000 mL

D) 5000 mL

How has the avian lung adapted to the metabolic demands of flight? A) Airflow through the avian lung is bidirectional like in mammals. B) There is more dead space within the avian lung so that oxygen can be stored for future use. C) Countercurrent circulation is present in the avian lung. D) Gas exchange occurs during both inhalation and exhalation.

D) Gas exchange occurs during both inhalation and exhalation.

Cyanide poisons mitochondria by blocking the final step in the electron transport chain. Human red blood cells placed in an isotonic solution containing cyanide are likely to _____. A) retain the normal cell shape, but the mitochondria will be poisoned B) lyse as the cyanide concentration increases inside the cell C) switch to anaerobic metabolism D) be unaffected

D) be unaffected

The Bohr shift on the oxygen-hemoglobin dissociation curve is produced by changes in _____. A) the partial pressure of oxygen B) hemoglobin concentration C) temperature D) pH

D) pH

Which of the following events would be predicted by the Bohr shift effect as the amount of carbon dioxide released from your tissues into the blood capillaries increases? The amount of oxygen in _____. A) arterial blood would increase B) arterial blood would decrease C) venous blood would increase D) venous blood would decrease

D) venous blood would decrease

The diagnosis of hypertension in adults is based on the _____. A) measurement of fatty deposits on the endothelium of arteries B) measurement of the LDL/HDL ratio in peripheral blood C) percentage of blood volume made up of platelets D) blood pressure being greater than 140 mm Hg systolic and/or greater than 90 mm Hg diastolic

D) blood pressure being greater than 140 mm Hg systolic and/or greater than 90 mm Hg diastolic

Countercurrent exchange in the fish gill helps to maximize _____. A) blood pressure B) diffusion C) active transport D) osmosis

B) diffusion

When the air in a testing chamber is specially mixed so that its oxygen content is 10 percent and its overall air pressure is 400 mm Hg, then is _____. A) 400 mm Hg B) 82 mm Hg C) 40 mm Hg D) 4 mm Hg

C) 40 mm Hg