Deck 48: Respiratory Systems

Question 1

The group of vertebrates with the greatest capacity for gas exchange across the skin is the

Answer 1

Fish do not exchange gases across their skin; instead exchange of gases is facilitated by specialized gills. Hence, the option (a) is incorrect.
Terrestrial reptiles also use lungs for gas exchange, as do mammals and birds. Hence, the option (b) is incorrect.
The birds and mammals use lungs for gas exchange. Moreover, they do not have permeability for gas in their skin like amphibians. Hence, options (e) and (d).
Amphibians and few species of fish including eels, have unusually permeable skin. However, they rely on their lungs in conjunction with moist skin for gas exchange, on land. While, under water oxygen can diffuse across the skin because their unique circulatory system re-routes deoxygenated blood to the periphery where oxygen diffuses down its concentration gradient into the body. This system is much less efficient than the lungs, but nonetheless allows the amphibian to spend prolonged periods of time under water. The group of vertebrates with the greatest capacity for gas exchange across the skin is amphibians.
Hence, the correct option is (c) the amphibians.

Question 2

The countercurrent exchange mechanism in fish gills

A) maximizes oxygen diffusion into the bloodstream.
B) is a less efficient mechanism for gas exchange compared with mammalian lungs.
C) occurs because the flow of blood is in the same direction as water flowing across the gills.
D) is the same phenomenon observed in birds' lungs.
E) requires that the fish swallow water.

Answer 2

The countercurrent exchange mechanism of fish gills maximizes oxygen diffusion into the bloodstream. Internal gills of fish contain many plates of lamellae; plate like structures that branch from structures called filaments. The filaments are highly vascularized with vessels, containing oxygenated blood running along one side, and oxygen deficient blood running down the other side. Within lamellae, numerous capillaries that direct blood flow from the oxygen rich vessel to the oxygen poor one. Water enters the fish's mouth and flows between lamellae in the opposite direction of blood flowing through the capillaries, in a countercurrent exchange mechanism). Thus, creates a large concentration gradient between the deoxygenated blood and the water, causing oxygen to diffuse into the capillary. Hence, the correct option is (a) maximizes oxygen diffusion into the bloodstream
The countercurrent exchange mechanism in fish gills is more efficient than the mammalian lung. Since, it is also more energetically expensive because of the density of the water. Hence, the option (b) is incorrect.
In fish gills the countercurrent distribution, as discussed above, works when the flow of water and flow of blood run in opposite directions. Hence, the option (c) is incorrect.
Bird's lungs operate in an entirely different fashion. It does not follow the countercurrent distribution like fishes. Hence, the option (d) is incorrect.
The countercurrent exchange mechanism does not require the fish to swallow any water. In fact, water usually ejected from the fish is done through specialized cavities. Hence, the option (e) is incorrect.

Question 3

The tracheal system of insects

A) consists of several tracheae that connect to multiple lungs within the different segments of the body.
B) consists of extensively branching tubes that are in close contact with all the cells of the body.
C) allows oxygen to diffuse directly across the thin exoskeleton of the insect to the bloodstream.
D) cannot function without constant movement of the wings to move air into and out of the body.
E) provides oxygen that is carried through the animal's body in hemolymph.

Answer 3

Insects have tiny openings on either side of their body that open into tracheae, sturdy tubes that branch into an extensive system within the insect's body. The tracheae taper into thinner tracheoles, the beginning of which are filled with a very small amount of fluid. Air blowing through these tubes mixes with the fluid, and oxygen dissolves into it, by diffusing into nearby cells. Thus, the tracheal system of insects consists of extensively branching tubes that are in close contact with all cells of the body. Hence, the correct option is (b) consists of extensively branching tubes that are in close contact with all the cells of the body.
Insects do not have true lungs, nor does gas diffuse across the exoskeleton. Hence, the option the tracheal system of insects consists of several tracheae that connect multiple lungs in different segments of body and allow oxygen to diffuse across thin exoskeleton of insect to blood stream is incorrect. Hence, the options (a) and (c) are incorrect.
The tracheal system of insects, in the movement of the wings causes contraction of the abdomen and thorax by increasing ventilation. It is not necessary for the insect to breathe. Hence, the options insect tracheal system cannot function without constant movement of wings to move air into and out of the body and provides oxygen that is carried through the animal's body in hemolymph, is incorrect. Hence, the options (d) and (e) are incorrect.

Question 4

_____________ is secreted by type II alveolar cells in the mammalian lung to prevent the collapse of alveoli due to surface tension at the interface of air and extracellular fluid.

A) Hemoglobin
B) Myoglobin
C) Mucus
D) Water
E) Surfactant

Question 5

In negative pressure filling, air moves into the lungs when

A) the volume of the thoracic cavity increases.
B) the pressure in the thoracic cavity decreases.
C) air is forced down the trachea by muscular contractions of the mouth and pharynx.
D) all of the above
E) a and b only

Question 6

Which of the following factors does not alter the rate of breathing by influencing the chemoreceptors

A) PcO₂ in the blood
B) PO₂ in the blood
C) blood pH
D) blood glucose levels
E) H + concentration in the blood

Question 7

With rare exceptions, the majority of oxygen is transported in the blood of vertebrates

A) by binding to plasma proteins.
B) by binding to hemoglobin in erythrocytes.
C) as dissolved gas in the plasma.
D) as dissolved gas in the cytoplasm in the erythrocytes.
E) by binding to myoglobin.

Question 8

Discuss two ways in which animals exchange gases in an aqueous environment. What special adaptations facilitate this exchange

Question 9

Define countercurrent exchange as it relates to gas exchange in fishes.

Question 10

The driving force for diffusion of oxygen across the cells of a respiratory organ is the

A) difference in the partial pressure of oxygen (PO₂ ) in the environment and in the blood.
B) humidity.
C) partial pressure of carbon dioxide (PcO₂ ) in the blood.
D) air temperature.
E) PcO₂ in the atmosphere.

Question 11

Discuss the components of the mammalian respiratory system.

Question 12

Carbon dioxide is considered a harmful waste product of cellular respiration because it

A) decreases the pH of the blood.
B) decreases the H + concentration in the blood.
C) competes with oxygen for transport in the blood.
D) does all of the above.
E) does a and b.

Question 13

Explain some of the special adaptations for life at high altitudes; why are such adaptations necessary

Question 14

The process of bringing oxygenated water or air into contact with a gas-exchange surface is