The respiratory tract consists of the nose (nasal cavities),the nasopharynx, the pharynx, the larynx (which containsthe vocal cords), the trachea, the bronchi, and thebronchioles. The bronchi, along with the pulmonaryarteries and veins, enter the lungs, which consist of thealveoli, air sacs surrounded by a capillary network.

Inspiration begins when the respiratory centerin the medulla oblongata sends excitatory nerve impulsesto the diaphragm and the muscles of the rib cage. As theycontract, the diaphragm lowers and the rib cage movesupward and outward; the lungs expand, creating a partialvacuum, which causes air to rush in. The respiratory cen-ter now stops sending impulses to the diaphragm andmuscles of the rib cage. As the diaphragm relaxes, it re-sumes its dome shape, and as the rib cage retracts, air ispushed out of the lungs during expiration.

External respiration occurs when CO2 leaves bloodand O2 enters blood at the alveoli. Oxygen is transportedto the tissues in combination with hemoglobin as oxy-hemoglobin (HbO2). Internal respiration occurs whenO2 leaves blood and CO2 enters blood at the tissues. Car-bon dioxide is mainly carried to the lungs within theplasma as the bicarbonate ion (HCO3

−). Hemoglobincombines with hydrogen ions and becomes reduced(HHb).

There are a number of illnesses associated with therespiratory tract. In addition to colds and flu, the lungsmay be infected by the more serious pneumonia and tu-berculosis. Two illnesses that have been attributed tobreathing polluted air are emphysema and lung cancer.

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15RESPIRATORY SYSTEM

CHAPTER REVIEW

STUDY EXERCISES

Study the text section by section as you answer the questions that follow.

15.1 RESPIRATORY TRACT (P. 284)

• Air passes through a series of tubes before gas exchange takes place across a very extensive moist surface.

1. Complete this table.

Structure Function

a. _________________________________________________ Filter, warm, and moisten airGlottis b. _________________________________________________c. _________________________________________________ Sound productionTrachea d. _________________________________________________e. _________________________________________________ Passage of air to each lungBronchioles f. _________________________________________________g. _________________________________________________ Gas exchange

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2. Label the following diagram, using the alphabetized list of terms.epiglottisglottishard palatelarynxnasal cavitysoft palatetrachea

3. The nostrils contain a._________________, and the nasal cavity and trachea are lined with b._________________ to

screen the incoming air. Mucus, dust, and other material are moved into the c._________________ for swallowing or

expectoration. During swallowing, the d._________________ folds down over the glottis to keep food from entering

the trachea. The lungs of premature infants often lack a film called e._________________ that keeps their lung tissues

from sticking together.

15.2 MECHANISM OF BREATHING (P. 288)

• Respiration comprises breathing, external and internal respiration, and cellular respiration.

4. Label the following diagram, using the alphabetized list of terms.expiratory reserve volumeinspiratory reserve volumeresidual volumetidal volume

5. In the preceding diagram, the sum of the volumes labeled a, b, and c is termed the _____________________________.6. Indicate whether the following phrases describe inspiration (I) or expiration (E).

_____ a. lungs expanded_____ b. muscles (diaphragm and ribs) relaxed_____ c. diaphragm dome shaped_____ d. chest enlarged_____ e. less air pressure in lungs than in the environment

6000

4800

3600

2400

1200

0

2900

Time

a.

b.

d.

c.Vol

ume

of A

ir in

Lun

gs (

ml)

Inspiration and Expiration (p. 290)

• During inspiration, the pressure in the lungs decreased, and air comes rushing in. During expiration, increasedpressure in the thoracic cavity causes air to leave the lungs.

7. Put these statements in the proper sequence._____ a. Respiratory center stops sending nerve impulse to diaphragm and rib cage._____ b. Respiratory center sends nerve impulse to diaphragm and rib cage._____ c. Diaphragm relaxes, becomes dome shaped, and rib cage moves down and inward._____ d. Lungs expand as diaphragm lowers and rib cage moves upward and outward._____ e. Air goes rushing out as lungs recoil._____ f. Air comes rushing in as lungs expand.

15.3 GAS EXCHANGES IN THE BODY (P. 292)

• External respiration occurs in the lungs where oxygen diffuses into the blood and carbon dioxide diffuses outof the blood.

• Internal respiration occurs in the tissues where oxygen diffuses out of the blood and carbon dioxide diffusesinto the blood.

8. Match the statements with the terms that follow._____ a. entrance and exit of air into and out of lungs_____ b. exchange of gases between blood and tissue fluid_____ c. production of ATP in cells_____ d. exchange of gases between lungs and blood

Terms 1. internal respiration 2. cellular respiration 3. inspiration and expiration 4. external respiration

e. Next, place the terms in the proper sequence.

First _______ Second ________ Third ________ Last _________

9. Give the equation that describes how oxygen is transported in the blood. Label one arrow lungs and the reverse arrow tissues.

10. Give the equation that describes how most of the carbon dioxide is transported in the blood. Label one arrow lungs andthe reverse arrow tissues.a.

What is the name of the enzyme that speeds up this reaction? b.

Carbon dioxide transport produces hydrogen ions. Why does the blood not become acidic? c.

By what process does carbon dioxide move from the blood to the alveoli? d.

11. After studying Figure 15.8 in the text, answer these questions. Where does oxygen enter the blood?a.______________________________ Where does oxygen exit from the blood? b.______________________________

Where does carbon dioxide enter the blood? c.______________________________ Where does carbon dioxide exit

from the blood? d.______________________________ In the diagram, what two types of vessels are high in oxygen?e._______________________________________________________________________________________________

In the diagram, what two types of vessels are high in carbon dioxide? f.

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123

Binding Capacity of Hemoglobin

• The respiratory pigment hemoglobin transports oxygen from the lungs to the tissues and aids in the transportof carbon dioxide from the tissues to the lungs.

12. Hemoglobin is remarkably suited to the transport of oxygen. Why? a.

Why does a person die from carbon monoxide poisoning? b.

How does hemoglobin help with the transport of carbon dioxide? c.

15.4 RESPIRATION AND HEALTH (P. 295)

• The respiratory tract is especially subject to disease because it is exposed to infectious agents. Cigarettesmoking contributes to two major lung disorders—emphysema and cancer.

13. Match the descriptions in a–g to this key.Key cold and flu strep throat pneumonia tuberculosis emphysema pulmonary fibrosis lung cancer

Cells build a protective capsule around the bacteria. X rays can detect the presence of these capsules.a.______________________________ Rheumatic fever can be a complication. b.______________________________

Fibrous connective tissue builds up in the lungs after inhaling particles. c.______________________________

This is caused by a virus, and antibiotic therapy is not helpful. d.______________________________

This most often begins in a bronchus and is caused by smoking cigarettes. e.______________________________

Lungs balloon because air is trapped in the alveoli. f.______________________________

Lobules of lungs fill with fluid, caused by a pathogen. g.______________________________14. Why do women now suffer from lung cancer rates equivalent to those of men when in the past they did not?

CHAPTER TEST

____ 4.How are foreign particles trapped before enter-ing the lungs?a. coarse hair inside nostrilsb. mucus in the nasal cavityc. cilia in the nasal cavity and trachead. All of these are correct.

____ 5.Which of these constricts during an asthma at-tack?a. tracheab. bronchusc. bronchioled. pharynx

____ 6.The alveolia. are sacs in the lungs.b. contain capillaries.c. are where gas exchange occurs.d. All of these are correct.

OBJECTIVE TEST

Do not refer to the text when taking this test.____ 1.Why is oxygen needed by the body?

a. to aerate the lungsb. to cleanse the bloodc. to produce ATPd. Both a and b are correct.

____ 2.The structure(s) that receive(s) air after the tra-chea is(are) thea. pharynx.b. bronchi.c. bronchiolus.d. alveoli.

____ 3.Which structure carries both air and food?a. larynxb. pharynxc. trachead. esophagus

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____ 7.Which of these contains the vocal cords?a. glottisb. epiglottisc. pharynxd. larynx

____ 8.Before oxygen is picked up in the lungs by he-moglobin, it first diffuses through (a) alveolar cells,(b) blood plasma, (c) red blood cell plasma mem-branes, and (d) capillary walls, though not nec-essarily in this order. What is the correct order?a. a, b, d, cb. a, d, b, cc. d, a, c, bd. d, b, a, ce. a, b, c, d

____ 9.When the lungs recoil,a. inspiration occurs.b. external respiration occurs.c. internal respiration occurs.d. expiration occurs.e. All of these are correct.

____10.The respiratory centera. is stimulated by carbon dioxide.b. is located in the chest.c. sends nerve impulses to lung tissue.d. is stimulated by oxygen levels.

____11.The amount of air that enters or leaves the lungsduring a normal respiratory cycle is thea. tidal volume.b. respiratory volume.c. residual volume.d. vital capacity.

____12.The maximum amount of air a person can ex-hale after taking the deepest breath possible is ameasure of thea. residual volume.b. tidal volume.c. vital capacity.d. inspiratory reserve volume.

____13.External respiration is defined asa. an exchange of gases in the lungs.b. breathing.c. an exchange of gases in the tissues.d. cellular respiration.

____14.Which gas is carried partially by the plasma?a. O2

b. CO2

c. both O2 and CO2

d. Neither O2 nor CO2.____15.CO2 enters the blood as a result of

a. active transport.b. diffusion.c. blood pressure.d. air pressure.

____16.The enzyme carbonic anhydrase causesa. carbon dioxide to react with water.b. carbon dioxide to react with bicarbonate ions.c. water to react with hydrogen ions.d. Both b and c are correct.

____17.Hemoglobin combines witha. oxygen more readily in the lungs.b. carbon dioxide more readily in the tissues.c. oxygen more readily in the tissues.d. carbon dioxide more readily in the lungs.e. Both a and b are correct.

____18.Hemoglobin carriesa. O2.b. CO2.c. hydrogen ions.d. All of these are correct.

____19.Which lung disorder is not caused by a pathogen?a. pneumoniab. tuberculosisc. emphysemad. flu

____20.Smoking cigarettesa. causes tuberculosis.b. leads to emphysema and cancer.c. increases the vital capacity of the lungs.d. leads to good health and longer life.

Match the items in the key to phrases 21–23.Key a. pneumonia b. lung cancer c. infant

respiratory distress

____21.nonfunctional tissues interfere with gas exchange____22. fluid-filled lobules____23.alveolar collapse due to high surface tension____24.Which body system does the respiratory system

aid by providing oxygen so neurons can func-tion properly?a. nervous systemb. lymphatic systemc. circulatory systemd. integumentary system

____25.Which body system helps the respiratory systemby protecting the lungs and providing points forbreathing muscle attachment?a. circulatory systemb. skeletal systemc. muscular systemd. urinary system

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THOUGHT QUESTIONS

26. Explain how expiration occurs once the lungs have filled with air.

27. Relate the large surface area provided by the alveoli to the process by which external respiration occurs.

Test Results: _______ number correct ÷ 27 = _________ × 100 = _______%

ANSWER KEY

STUDY EXERCISES

1. a. nasal cavities b. passage of air into larynx c. lar-ynx d. passage of air to bronchi e. bronchi f. passageof air to lungs g. lungs 2. a. nasal cavity b. hard palatec. soft palate d. epiglottis e. glottis f. larynx g. trachea3. a. coarse hairs b. cilia c. pharynx d. epiglottis e. sur-factant 4. a. inspiratory reserve volume b. tidal volumec. expiratory reserve volume d. residual volume 5. vitalcapacity 6. a. I b. E c. E d. I e. I 7. b, d, f, a, c, e8. a. 3 b. 1 c. 2 d. 4 e. 3, 4, 1, 2

9.lungs

Hb + O2________ HbO2

tissues

10. a.tissues tissues

CO2 + H2O ________ H2CO3 ________ H + + HCO3

−

lungs lungsb. carbonic anhydrase c. Hemoglobin combines with ex-cess hydrogen ions. d. diffusion 11. a. lungs b. tissuesc. tissues d. lungs e. pulmonary vein and aorta (systemicarteries) f. venae cavae (systemic veins) and pulmonaryartery 12. a. It easily combines with oxygen in the lungs

and easily gives it up in the tissues. b. Hemoglobin com-bines with carbon monoxide preferentially to oxygen.c. It combines with carbon dioxide to form carbamino-hemoglobin, and picks up hydrogen ions. 13. a. tuber-culosis b. strep throat c. pulmonary fibrosis d. cold andflu e. lung cancer f. emphysema g. pneumonia14. Women now smoke cigarettes as frequently as men.In the past, it was socially less acceptable for women tosmoke.

CHAPTER TEST

1. c 2. b 3. b 4. d 5. c 6. d 7. d 8. b 9. d10. a 11. a 12. c 13. a 14. b 15. b 16. b17. e 18. d 19. c 20. b 21. b 22. a 23. c24. a 25. b 26. The diaphragm relaxes when the res-piratory center stops sending messages to contract. Oncerelaxation occurs, expiration is passive. Air leaves the lungswith the elastic recoil of the lungs. Muscle contractioncan force additional air from the lungs. 27. Since oxy-gen enters the capillaries of the alveoli by diffusion, a pas-sive process, a large surface area is required.