Biology: The Dynamic Science

Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter 46

Gas Exchange: The Respiratory System - all with Video Answers

Educators

Chapter Questions

Problem 1

Which of the following describes a respiratory medium?
a. the liver of an amphibian, in which the rate of diffusion is high
b. neurons in the human brain, where $C O_{2}$ moves from the neurons to the blood
c. the $\mathrm{O}_{2}$ in the blood of humans
d. epithelial cells of fish that are in contact with the air
e. air and water

Joanna Quigley

Joanna Quigley

Numerade Educator

Problem 2

Which of the following describes a respiratory surface?
a. a surface consisting of multiple layers of epithelial cells
b. the exoskeleton of an insect
c. the nasal passages of a mammal
d. thin surface consisting of a single layer of epithelial cells
e. the outer membrane of a mitochondrion

Joanna Quigley

Numerade Educator

Problem 3

A geothermal HVAC (heating, ventilating, and air conditioning) system air-conditions your house by passing warm air pulled from the house past a continuous flow of cool water pulled from the ground. How this heat exchanger works is analogous to:
a. countercurrent exchange of gases in fish gills.
b. diffusion of $\mathrm{O}_{2}$ from blood to cells in shark tissues.
c. diffusion of $\mathrm{CO}_{2}$ from cells to blood in crabs.
d. use of $\mathrm{O}_{2}$ in cells in insects.
e. excretion of $\mathrm{CO}_{2}$ from mammalian cells.

Joanna Quigley

Numerade Educator

Problem 4

Tracheal systems are characterized by:
a. closed circulatory tubes that move gases.
b. spiracles that move gases between cells and body fluids.
c. body movements that compress and expand air sacs to pump air.
d. positive pressure breathing, which swallows air into the body.
e. negative pressure breathing, which lowers air pressure at the respiratory surfaces.

Joanna Quigley

Numerade Educator

Problem 5

The partial pressure of $\mathrm{O}_{2}$ in the atmosphere is $160 \mathrm{mm} \mathrm{Hg}$, but when $\mathrm{O}_{2}$ moves into the blood its partial pressure is one third lower than the atmospheric partial pressure. Which structure is it moving through at this partial pressure?
a. alveoli
b. bronchi
c. bronchioles
d. tracheae
e. pharynges

Joanna Quigley

Numerade Educator

Problem 6

As a speed skater finishes the last lap of a race:
a. his diaphragm and rib muscles contract when he exhales.
b. positive pressure brings air into his lungs.
c. his lungs undergo an elastic recoil when he inhales.
d. his tidal volume is at vital capacity.
e. his residual volume momentarily reaches zero.

Joanna Quigley

Numerade Educator

Problem 7

A teenager is frightened when she is about to step onto the stage but then remembers to breathe deeply and slowly as she faces the audience. What is occurring here?
a. Interneurons in the medulla cause the rib muscles to relax, followed later by stimulation and contraction of the intercostal muscles.
b. Signals from the pons override the initial brain stem stimuli.
c. The limbic system stabilized her emotional state, so there is no change in the mechanical movement of air.
d. The brain signals the aortic bodies in the carotid arteries to adjust the breathing rate.
e. Initial low $\mathrm{CO}_{2}$ blood levels causing high $\mathrm{pH}$ are followed by increased $\mathrm{CO}_{2}$ levels that lower $\mathrm{pH}$.

Joanna Quigley

Numerade Educator

Problem 8

Oxygen enters the blood in the lungs because relative to alveolar air:
a. the $\mathrm{CO}_{2}$ concentration in the blood is high.
b. the $\mathrm{CO}_{2}$ concentration in the blood is low.
c. the $\mathrm{O}_{2}$ concentration in the blood is high.
d. the $\mathrm{O}_{2}$ concentration in the blood is low.
e. the process is independent of gas concentrations in the blood.

Joanna Quigley

Numerade Educator

Problem 9

A hemoglobin $\mathrm{O}_{2}$ dissociation curve:
a. demonstrates that hemoglobin is about $50 \%$ saturated in the alveoli.
b. shifts to the left when $\mathrm{pH}$ rises.
c. demonstrates that hemoglobin holds less $\mathrm{O}_{2}$ when the $\mathrm{pH}$ is higher.
d. illustrates that oxygen saturation is not dependent on $\mathrm{CO}_{2}$ levels.
e. demonstrates why hemoglobin can bind $\mathrm{O}_{2}$ at high $\mathrm{pH}$ in the lungs and release it at lower $\mathrm{pH}$ in the tissues.

Joanna Quigley

Numerade Educator

Problem 10

The majority of $\mathrm{CO}_{2}$ in the blood:
a. is in the form of carbonic acid and bicarbonate ions.
b. dissociates to add $\mathrm{H}^{+}$ to the blood to raise its $\mathrm{pH}$ to 7.4
c. has a lower $P_{C O_{2}}$ than the $P_{C O_{2}}$ in the alveolar air.
d. increases in the lung capillaries, which have a higher $\mathrm{pH}$ than the tissue capillaries.
e. can be displaced on the hemoglobin molecule by $\mathrm{CO}$ if $\mathrm{CO}$ is inhaled.

Joanna Quigley

Numerade Educator

Problem 11

Smoking has traditionally been considered to reduce the ability of athletes to run without becoming exhausted. Why might this be true?

Joanna Quigley

Numerade Educator

Problem 12

People are occasionally found unconscious from breathing too much $\mathrm{CO}_{2}$ (as from a charcoal heater placed indoors) or too much $\mathrm{CO}$ (as from auto exhaust in a closed garage). Would it be more advantageous to give pure $\mathrm{O}_{2}$ to a person breathing too much $\mathrm{CO}_{2}$ than simply moving the person to fresh air? Why? Which-pure $\mathrm{O}_{2}$ or fresh air-would be best for a person unconscious from breathing CO? Why?

Joanna Quigley

Numerade Educator

Problem 13

Hyperventilation, or overbreathing, is breathing faster or deeper than necessary to meet the body's needs. Hyperventilation reduces the $\mathrm{CO}_{2}$ content of blood, but does not significantly increase the amount of $\mathrm{O}_{2}$ available to tissues. Why might this be so?

Joanna Quigley

Numerade Educator

Problem 14

Propose a hypothesis for the effect of zero gravity on respiration, and design an experiment to test the hypothesis.

Joanna Quigley

Numerade Educator

Problem 15

From what you have learned in this chapter and in Chapter $32,$ do you think lungs evolved once, or on several occasions? Justify your answer.

Joanna Quigley

Numerade Educator