Good Respiratory Health Is Essential
LEARNING OBJECTIVES
1.
Explain
how the respiratory system responds to
exercise.
2.
Describe
how the respiratory system changes
with age.
3.
Link
smoking and various respiratory diseases
with changes in respiratory function.
ood respiratory health affects all aspects of
your life. The respiratory system oxygenates
your cells and tissues, which allows them to
function properly, helps cells produce ATP,
and enables you to endure physical activities such as
strenuous exercise and play. Respiratory functions can be
compromised by aging, disease, and the effects of smok-
ing and respiratory disorders. Let’s start our discussion of
respiratory health by examining the effects of exercise on
the respiratory system.
Respiratory Actions Change
with Physical Activity
When you begin to exercise, proprioceptors in your mus-
cles and joints stimulate the respiratory center of the
brain to increase the rate and depth of breathing (Fig-
ure 13.9). Because these proprioceptors are components
of neurological reflexes, this change of breathing kicks
in during the first few minutes of activity. ATP is needed
for muscular activity, so as you continue to exercise, the
cells rapidly begin to use up oxygen, generate carbon di-
oxide, and form hydrogen ions in the cellular respiration
process. These changes alter the levels of the gases in
the blood supply, stimulating peripheral chemoreceptors
to initiate feedback to the respiratory center, resulting in
increased breathing rate and depth. This altered respira-
tion increases oxygenation of the blood and removal of
carbon dioxide, which meets the needs of working mus-
cles and returns the blood levels of the various gases to
more normal levels.
E x e r c i s e s t i m u l a t e s t h e r e s p i r a t o r y c e n t e r , h e a r t ,
a n d l u n g s t o d e l i v e r m o r e o x y g e n t o w o r k i n g m u s c l e s •
F ig u r e 1 3 . 9
Exercise
The metabolism of
working muscles:
• Produces CO2, increasing PC(O
• Consumes O2, decreasing PO
1
Releases H+, decreasing blood pH
Brain
and Heart
Lungs
Proprioceptors in
the muscles and
joints stimulate
the respiratory
center and
sympathetic
nervous system.
The changes in
p co
2
p o
2 and H+
stimulate peripheral
chemoreceptors.
The respiratory
center in the
brain stimulates
respiratory muscles.
Peripheral
chemoreceptors
stimulate the
respiratory center.
The effects:
• The rate and depth of
breathing increase
• External respiration
increases
Sympathetic
activity increases
heart rate and
contractility, and
pulmonary blood
flow increases.
390 CHAPTER 13
The Respiratory System
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