771
CHAPTER NINETEEN
Respiratory System
19.7
GAS TRANSPORT (PAGE 762)
Blood transports gases between the lungs and the body cells.
1. Oxygen transport
a. Oxygen is mainly transported with hemoglobin
molecules.
b. The resulting oxyhemoglobin is unstable and
releases its oxygen in regions where the P
O
2
is low.
c. More oxygen is released as the plasma P
CO
2
increases, as the blood becomes more acidic, and
as the blood temperature increases.
2. Carbon dioxide transport
a. CO
2
may be carried in solution, either as dissolved
CO
2
, CO
2
bound to hemoglobin, or as a bicarbonate
ion.
b. Most CO
2
is transported in the form of bicarbonate
ions.
c. Carbonic anhydrase speeds the reaction between
CO
2
and water to form carbonic acid.
d. Carbonic acid dissociates to release hydrogen ions
and bicarbonate ions.
19.8
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
system.
2. Loss of cilia, thickening of mucus, and impaired
macrophages raise the risk of infection.
3. CalciF
ed cartilage, skeletal changes, altered posture,
and replacement of smooth muscle with F
brous
connective tissue in bronchioles make breathing more
difF
cult. Vital capacity diminishes.
4. The lungs contain a greater proportion of “stale” air.
5. Alveoli coalesce and become shallower, slowing gas
exchange.
d. Peripheral chemoreceptors are in the carotid bodies
and aortic bodies of certain arteries.
(1) These chemoreceptors sense low oxygen
levels.
(2) When oxygen levels are low, alveolar
ventilation increases.
e. Stretching the lung tissues triggers an infl
ation
refl ex.
(1) This refl
ex reduces the duration of inspiratory
movements.
(2) This prevents overinfl
ation of the lungs during
forceful breathing.
f. Hyperventilation decreases CO
2
levels, but
this is
dangerous when associated with breath holding
during underwater swimming.
19.6
ALVEOLAR GAS EXCHANGES (PAGE 759)
Gas exchange between the air and the blood occurs in the
alveoli.
1. Alveoli
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
are obstructed.
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
blood; CO
2
diffuses from the blood into the
alveolar air.
19.1 Introduction
1
List the general functions of the respiratory system. (p. 736)
19.2 Why We Breathe
2
Explain why oxygen is required at the cellular level.
(p. 736)
19.3 Organs of the Respiratory System
3
Distinguish between the upper and lower respiratory
tracts. (p. 737)
4
Explain how the nose and nasal cavity F
lter incoming air.
(p. 737)
5
Name and describe the locations of the major sinuses.
(p. 738)
6
Explain how a sinus headache may occur. (p. 738)
CHAPTER ASSESSMENTS
7
The pharynx is also known as the: (p. 740)
a. nasal cavity
b. oral cavity
c. voice box
d. throat
8
Name and describe the functions of the cartilages of the
larynx. (p. 740)
9
Match the following structures with their descriptions:
(pp. 740–746)
(1) true vocal cords
A. serous membrane on lungs
(2) false vocal cords
B. contains the vocal cords
(3) larynx
C. vibrate to make sound
(4) visceral pleura
D. air sacs
(5) alveoli
E.
muscular folds that close the
glottis
740
previous page 801 David Shier Hole's Human Anatomy and Physiology 2010 read online next page 803 David Shier Hole's Human Anatomy and Physiology 2010 read online Home Toggle text on/off