Contain some residual air with a lower oxygen partial pressure than air
After exhalation, the lungs and airways of mammals….
ventilate; perfuse
Breathing mechanisms _______ the environmental side of the gas exchange surface, while circulatory systems _______ the internal side of the surface
diaphragm contracts and increases the volume of the lungs while also lowering pressure
At rest (not exercising) air flows into the lungs of mammals during inhalation because the
with tidal breathing there is residual stale air in the lungs that mixes with new air during each breath.
Although 21 percent of air is oxygen, the alveoli of the lungs do not contain air with this much oxygen because
Because of the relatively high altitude of Antonito, Colorado, the town has a normal barometric pressure of about 0.78 atm as at sea level. The partial pressure of O2 in Antonito’s air is approximately _______ atm. (Hint: Air is approximately 21 percent oxygen.)
Birds have unidirectional air flow and thinner diffusion distances in their lungs than mammals.
Why are you more likely to find birds than mammals at high altitudes?
oxygen and carbon dioxide
The primary respiratory gases are

So it depends on:
Partial Pressure

Respiratory gas exchange between an animal’s body fluids and its environment depends on all of the following except
Mechanisms to adjust the temperature of air or water to increase diffusion
Which of the following is not an adaptation for respiratory gas exchange?
Animals have evolved bulk flow processes to transport O2 over short distances such as the diameter of a cell.
Which of the following about bulk flow is false?
low; low
The limiting effects of water in oxygen exchange can best be described as _______ diffusion rate and _______ oxygen content compaired to air.
Dry air is about 78 percent nitrogen; therefore, the partial pressure of nitrogen at sea level is about _______ atm.
elastic recoil of the lung tissues.
During rest, the process of exhalation in mammals is brought about by
active transport of gases at the molecular level.
Gas exchange in animals never involves
air sacs that permit unidirectional air flow through the lungs
In addition to possessing lungs, birds have _______
The oxygen content of air is higher than that of water even at equal partial pressures.

Oxygen diffuses more slowly in water than in air.

More energy is required to move water than air because water is denser and more viscous.

Oxygen can be exchanged more easily in air than in water because
water is more dense and viscous than air and holds less O2 per unit volume.
Rapid gas exchange can be accomplished more easily in air than in water because
As O2 is consumed, the bubble O2 partial pressure drops below the water O2 partial pressure.
Small insects may take a bubble of air underwater when they dive. The bubble absorb O2 from the water, because
Increase surface area (A)
The large number of filaments and thin lamella in fish gills..
Negatively related to
The rate at which a gas diffuses across a membrane is _______ the thickness of the membrane.
Branched air tubes called tracheae that supply capillaries.
The respiratory system of insects consists of
Countercurrent flow
Which of the following characterizes the gills of fish?
Gases always diffuse from high to low partial pressure, but not always from high to low concentration
Which of the following statements is true?
Which of the following structures is the site of gas exchange in bird lungs?

All true endotherms breath air, even if they live in water

Even at the same partial pressure, a liter of water will only contain about 1/25th as much O2 as a liter of air

Gasses diffuse thousands of times faster in air than in water

Ventilating gills with water requires far more energy than ventilating lungs with air

Which statement is true?

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