BIOLOGY 12: CHAPTER 15 - REVIEW WORKSHEET KEY
RESPIRATORY SYSTEM
A. CHAPTER REVIEW
1.
i) Breathing: Inspiration = inhalation or breathing in. Expiration = exhaling or breathing out
ii) External respiration = gas exchange between air and blood.
iii) Internal respiration = gas exchange between blood and lymph fluid.
iv) Cellular respiration = final destination in which ATP is produced in cells.
2. As air moves along the air passages, air is cleansed, warmed and moistened. As air is
expired, air carries out heat and moisture (which is deposited inside the nose).
3. Sinus headache result from colds or allergic reactions that block the sinus ducts so there
is a build up of mucus in the air-filled cavity in the skull.
4. The oral cavity and the esophagus temporarily join during swallowing.
5. Top of larynx = glottis. Food doesn’t enter glottis when food is swallowed because the
larynx moves up against the epiglottis, a flap of tissue that blocks food from passing into the
larynx.
6. Tension on vocal cords determine the pitch of the voice; the greater the tension as the
glottis becomes more narrow = the higher the pitch; the wider the glottis, the lower the
pitch. Loudness of voice depends on the amplitude of the vibrations, the degree to which
the vocal cords vibrate.
7. C-shaped cartilaginous rings hold the trachea open, and its open part faces the
esophagus which allows the esophagus to expand during swallowing.
8. Cilia in the trachea keep the lungs clean by sweeping mucus/impurities.
9. Tracheotomy = If trachea is blocked because of illness or accidental swallowing of a
foreign object, possible to insert a breathing tube by way of an incision made in the
trachea. Tube acts as artificial air intake and exhaust duct.
10. As bronchial tubes subdivide, their walls become thinner and the small rings of
cartilage are no longer present. Each bronchiole terminates in an elongated space
enclosed by a multitude of air pockets or sacs called alveoli (singular = alveolus). Alveoli
make up lungs.
11. Infant respiratory distress syndrome = underdeveloped lungs collapse in premature
infants due to the lack of surfactant.
12. The intrapleural pressure is LOWER than the atmospheric pressure to prevent alveoli
from collapsing
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13.
i) Group of neurons in the respiratory centre that exhibits an automatic rhythmic discharge
that triggers inspiration
ii) The presence of CO2 & H+ ions
iii) Low O2 levels
14. When stimulated, diaphragm contracts and lowers; rib cage moves upward and
outward.
15. Inspiration is an active process. Humans breathe by negative pressure because air
comes in because lungs have already opened up, air does not force the lungs open.
16. Lungs recoil as pressure increases and air is pushed out during expiration.
17. Can be an active process b/c contraction of intercostal muscles can force rib cage to
move down & in. Also when abdominal wall muscles are contracted, increased pressure
helps expel air.
18. Tidal volume = the normal amount of air moved in & out of the lungs when person is at
rest. About 500mL
Vital capacity = the sum of Tidal Volume, Inspiratory Reserve Volume, & Expiratory Reserve
Volume. The maximum amount of air moved in & out on deep breathing
Inspiratory reserve volume = the maximum amount of forcibly inspired air (into the lungs)
Inflating your lungs completely (deep breathing) can hold ~ 3400 mL.
Expiratory reserve volume = the maximum amount of forcibly expired air (out of the lungs)
Contracting the abdominal & thoracic muscles can release ~ 1400 mL.
19. 6.3L
20. External respiration occurs in the pulmonary capillaries. Diffusion governs gas exchange
at this site. Capillaries cover alveoli which allows this exchange to occur.
21. CO2 diffuses out of the blood into the alveoli because PCO2 is greater in the pulmonary
capillaries. CO2 is carried out as bicarbonate ions HCO322. Hemoglobin in blood becomes oxyhemoglobin when partial pressure of oxygen
increases in lungs. This relates to temperature and pH because haemoglobin takes up
oxygen more readily in cool temperatures and neutral pH; gives up oxygen more readily at
warm temperatures and acidic pH.
23. Oxygen diffuses out of blood and into tissue during internal respiration because [O2] in
tissue is low.
24. At tissue site, carbonic anhydrase in RBC’s act as an enzyme to speed up reaction.
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25. Carbon dioxide is transported in blood by diffusion. It enters RBC where small amounts
combine with hemoglobin to form carbaminohemoglobin. The most abundant way for
CO2 transport is when it combines with water to form carbonic acid which dissociates to
hydrogen and bicarbonate ions.
26. Important for haemoglobin to combine with excess hydrogen ions to maintain pH.
B. COMPLETION AND SHORT ANSWER QUESTIONS
1. The two processes involved in breathing are inspiration and expiration .
2. Fill in the blanks to describe the path that air takes in sequence: nasal cavities pharynx glottis larynx trachea bronchi brochioles alveoli.
3. During inspiration, the rib cage moves up and outward; the diaphragm moves
downward.
4. The primary (main) stimulus for breathing is the amount of CO2 in the blood.
5. Oxygen moves from the alveoli to the capillaries by means of diffusion.
6. Carbon dioxide is carried primarily in the plasma as bicarbonate (HCO3-) ions.
7. Hemoglobin readily takes up oxygen in the lungs where the pH is neutral and the
temperature is cool (cool, warm, hot)
8. At the tissues, O2 diffuses out of the blood and carbon dioxide (2 words) diffuses into the
blood.
10. a) The soft palate pushes to the back of the throat over the nasal passage.
b) The epiglottis, a flap of tissue, covers the glottis so that no food passes into the larynx.
12.
Inspiration lungs are expanded
Expiration muscles in the diaphragm and ribcage are relaxed
Expiration diaphragm has a dome shape
Inspiration chest is enlarged
Inspiration there is less air pressure in the lungs than in the atmosphere
13. Sequence: B D F G A C E
14.
a) Pulmonary capillaries (lungs)
b) Systemic capillaries
c) Systemic capillaries
d) Pulmonary capillaries (lungs)
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e) Pulmonary vein, systemic arteries
f) Pulmonary artery, vena cava
15. Transport of Gases (refer to p. 290)
a)
Hb + ↓O2
lungs
 HbO2
tissues
b)
H+
+
HCO3-
Lungs
Lungs
 H2CO3  H2O + CO2↑
Tissues
tissues
16. The enzyme that speeds up the reaction in question in 15b is carbonic anhyrdase.
17. The globin portion of the hemoglobin combines with excess H+ ions produced by
reaction and becomes HHb (reduced hemoglobin) so pH of blood does not become
acidic.
18. It gives up H+ ions it has been carrying, so it is now readily takes up O2 at cool
temperature, and neutral pH.
19. Small amount of CO2 combines with Hb, forming carbaminohemoglobin.
20. The name of an instrument used to measure the amount of air that can be maximally
inhaled and exhaled is a spirometer.
21. The operation used to place a tube inside the trachea is termed a tracheotomy.
C. TRUE/FALSE QUESTIONS
If the statement is false, rewrite the statement as a true one.
1. Answer: F
Restatement: Diffusion of gases occurs in both the tissues and the lungs.
2. Answer: F
Restatement: The trachea is held open by cartilaginous rings so that air
can pass down more easily.
3. Answer: T
4. Answer: F
capillary wall.
Restatement: The alveolus is a thin-walled air sac surrounded by a thin
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5. Answer: F
Restatement: The thoracic cavity and lungs are separated by a fluidfilled space having a negative pressure.
6. Answer: F
Restatement: Chemoreceptors found in the carotid and aortic bodies
communicate with the respiratory centre in the medulla oblongata.
7. Answer: T
8. Answer: F
Restatement: The direction in which gases move between the lungs and
the blood is determined by diffusion ( [ ] gradient).
9. Answer: T
10. Answer: F
cage.
Restatement: The pleural membrane separates the lungs from the rib
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