GAS TRANSPORT (PAGE 762)
Blood transports gases between the lungs and the body cells.
1. Oxygen transport
a. Oxygen is mainly transported with hemoglobin
b. The resulting oxyhemoglobin is unstable and
releases its oxygen in regions where the P
c. More oxygen is released as the plasma P
increases, as the blood becomes more acidic, and
as the blood temperature increases.
2. Carbon dioxide transport
may be carried in solution, either as dissolved
bound to hemoglobin, or as a bicarbonate
b. Most CO
is transported in the form of bicarbonate
c. Carbonic anhydrase speeds the reaction between
and water to form carbonic acid.
d. Carbonic acid dissociates to release hydrogen ions
and bicarbonate ions.
LIFE-SPAN CHANGES (PAGE 767)
The lungs, respiratory passageways, and alveoli undergo
aging-associated changes exacerbated by exposure to
polluted air. However, the increased work required to
breathe with age is typically not noticeable unless one
engages in vigorous exercise.
1. Exposure to pollutants, smoke, and other particulates
raises risk of developing diseases of the respiratory
2. Loss of cilia, thickening of mucus, and impaired
macrophages raise the risk of infection.
ed cartilage, skeletal changes, altered posture,
and replacement of smooth muscle with F
connective tissue in bronchioles make breathing more
cult. Vital capacity diminishes.
4. The lungs contain a greater proportion of “stale” air.
5. Alveoli coalesce and become shallower, slowing gas
d. Peripheral chemoreceptors are in the carotid bodies
and aortic bodies of certain arteries.
(1) These chemoreceptors sense low oxygen
(2) When oxygen levels are low, alveolar
e. Stretching the lung tissues triggers an inﬂ
(1) This reﬂ
ex reduces the duration of inspiratory
(2) This prevents overinﬂ
ation of the lungs during
f. Hyperventilation decreases CO
dangerous when associated with breath holding
during underwater swimming.
ALVEOLAR GAS EXCHANGES (PAGE 759)
Gas exchange between the air and the blood occurs in the
a. The alveoli are tiny sacs clustered at the distal ends
of the alveolar ducts.
b. Some alveoli open into adjacent air sacs that
provide alternate pathways for air when passages
2. Respiratory membrane
a. The respiratory membrane consists of the alveolar
and capillary walls.
b. Gas exchange takes place through these walls.
3. Diffusion through the respiratory membrane
a. Gases diffuse from regions of higher partial
pressure toward regions of lower partial pressure.
b. Oxygen diffuses from the alveolar air into the
diffuses from the blood into the
List the general functions of the respiratory system. (p. 736)
19.2 Why We Breathe
Explain why oxygen is required at the cellular level.
19.3 Organs of the Respiratory System
Distinguish between the upper and lower respiratory
tracts. (p. 737)
Explain how the nose and nasal cavity F
lter incoming air.
Name and describe the locations of the major sinuses.
Explain how a sinus headache may occur. (p. 738)
The pharynx is also known as the: (p. 740)
a. nasal cavity
b. oral cavity
c. voice box
Name and describe the functions of the cartilages of the
larynx. (p. 740)
Match the following structures with their descriptions:
(1) true vocal cords
A. serous membrane on lungs
(2) false vocal cords
B. contains the vocal cords
C. vibrate to make sound
(4) visceral pleura
D. air sacs
muscular folds that close the