Download 3.15 Answers

3.15 THE RESPIRATORY SYSTEM
TRY THIS ACTIVITY: FITNESS TEST (VO 2 max)
(Page 218)
(a) Answers will vary depending on students’ results. A male student runs a distance of 400 m in a time of 1 min
30 sec.
VO2 max ((400 m/1.5 min) 0.172) 10.4
VO2 max (45.9) 10.4
VO2 max 56.3 mL/kg/min
This is considered “good” for a male teenager.
Additional Question (in workbook only)
The same student runs a distance of 2400 m in 12 min.
VO2 max
VO2 max
44
(2
.7
40
m
0
L
–
/k
5
g
0
/m
5)
in
VO2 max
44.7 m
18
L
9
/k
5
g/min
VO2 max 42.3 mL/kg/min
The results are not the same. This suggests that these measurements are significantly influenced by the
circumstances
under which one is exercising. VO2 max may vary with respect to the nature of the activity and the individual’s
particular
fitness and training under different conditions.
SECTION 3.15 QUESTIONS
(Pages 223–224)
Understanding Concepts
1. The main function is gas exchange; specifically, obtaining and supplying oxygen to the blood from the
environment
and releasing waste carbon dioxide from the blood into the environment.
2. The respiratory system and circulatory system are intimately related. The respiratory system exchanges gases
directly
with the blood of the circulatory system.
3. As gases have very low solubility they cannot be stored for long periods of time. A small but continuous supply
of
oxygen gas must be obtained and the waste product, carbon dioxide, must be released in a similar way.
4. (a) epiglottis—prevents foods and liquids from entering the trachea and respiratory system
(b) trachea—carries air to and from the lungs from the sinuses/oral cavity
(c) cartilaginous rings—prevents the trachea and other large air passages from collapsing yet permits them to be
highly flexible
(d) goblet cells—produce mucus to coat the inner lining of the respiratory system and catch and remove
particulates
(e) cilia—tiny hairs that beat in unison to carry the mucus and trapped particulates up and out of the respiratory
tract
(distance travelled in a 12-min run (in metres) – 505)
44.7 mL/kg/min
NEL Section 3.15 109
(f) alveoli—the microscopic dead-end chambers of the lungs; gases are exchanged with the blood in the capillaries
lining their walls
5. An air molecule enters the nostrils and passes through the nasal passages moving to the pharynx at the back of
the oral
cavity. From there it passes behind the epiglottis and into the larynx. It passes between the vocal cords in the
larynx
and continues down the trachea before branching into either the right or left bronchus. From there it continues to
enter
smaller and smaller bronchioles until it reaches one of countless millions of blind sacs called alveoli. It then
diffuses
through the wall of the alveolus and into a capillary where it enters a red blood cell.
6. The larynx, or voice box, contains a pair of vocal chords that can be moved and manipulated by muscle groups.
As air
passes up from the lungs between the vocal cords it causes them to vibrate creating sounds or our “voice.” Males
have
larger vocal chords that vibrate at a lower frequency.
7.
8. During inspiration, the intercostal muscles and the diaphragm contract. During expiration these same muscles
relax.
9. The frog’s respiratory system is more varied. Due to the different life stages of the frog its respiratory system
includes
a gill system in the tadpole and a set of simple lungs in the adult. Unlike humans the frog also performs a large
fraction
of its gas exchange directly through its living moist skin. The frog must force air into its lungs by a gulping action.
Humans have a gas exchange system with advanced lungs and efficient gas exchange. The advantage for the frog is
its
ability to survive in different environments, including aquatic ones. The human system is much more efficient—a
requirement for meeting the very high demands of a large endotherm.
Applying Inquiry Skills
10. (a) Breathing rates would be highest during the 2–3 time interval when CO2 levels are at a maximum and O2
levels
are depleted. The brain controls breathing rate in direct response to CO2 levels in the blood.
(b) The subject began exercising at time 0. There is evidence that oxygen levels began to fall immediately
indicating
an increased demand for oxygen and an increase in carbon dioxide production.
(c) It appears that between time 4–6 carbon dioxide levels had become relatively stable; the breathing rate would
then
be back to normal levels.
11. (a) The evidence clearly shows that in this study thicker mucus was strongly correlated to an increase in
infections.
(b) If the mucus is too thick, it may be difficult for the delicate cilia to remove it from the lungs. This would allow
potential infectious agents to remain in the lungs and cause an infection. Also, the thick mucus may be physically
damaging to the delicate tissues of the alveoli.
Making Connections
12. (a) A narrowing of the bronchi would make gas exchange less efficient and therefore reduce the maximum
available
oxygen supply. This would make strenuous exercise difficult or impossible and could cause discomfort and distress.
(b) Occupations such as spray painting (in an autobody shop), woodworking (working in a dusty environment such
as a particle board plant), or working with animals—farmers (especially poultry) or veterinary assistants—would
have the potential to increase the incidence of bronchitis. Students might note that many of these risks can be
significantly reduced with proper health and safety precautions such as the use of masks and adequate air filtering
and ventilation systems.
110 U nit 3 Student Book Solutions NEL
O2
CO 2
capillary network
bronchiole
blood low in O2,
high in CO2
alveolar sac
blood high in O2,
low in CO2
alveolus
13. Many scuba courses are available including open water diving, wreck diving, cave diving, medic/first aid diver,
rescue
diver, and dive master. Careers include instruction; leading diving at tourist destinations; underwater construction;
and
search, rescue, and recovery.
Exploring
14. Answers may vary somewhat. The Heimlich manoeuvre is performed by producing a sudden increase in
pressure
within the chest cavity (by forcing the diaphragm upwards). The increase in pressure is often able to dislodge
objects
causing the choking.