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Respiratory Function, Breathing,
Respiration
BI 233
Exercise 40
Mechanics of Breathing
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Air moves from regions of higher
pressure to regions of lower
pressure.
The lungs fill with air or deflate
due to changes in air pressure.
During inspiration the diaphragm
contracts (with external
intercostals) increasing the volume
in thoracic cavity causing a
decrease in pressure in the lungs
which causes air to move into the
lungs.
When the diaphragm relaxes the
size of thoracic cavity decreases
causing increase in pressure and
therefore causing expiration.
Inspiratory Muscles
Diaphragm: Primary
Inspiratory muscle
2. External intercostal
muscles
 Forced inhalation:
1.
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Sternocleidomastoid
Scalenes
Serratus anterior
Pectoralis minor
Expiratory Muscles
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Normal exhalation is a
passive process, resulting
from the elastic recoil of
the lungs.
Forced exhalation
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Internal intercostals
muscles
Transverses thoracic
Abdominal muscles
Clinical Application
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Adequate pulmonary ventilation is
critical
Reduction in pulmonary ventilation
can cause increased CO2
(hypercapnia) producing acidosis
Increased pulmonary ventilation can
lead to a reduction in CO2
(hypocapnia) producing alkalosis.
Changes in CO2 concentrations can
alter breathing rates
*When doing experiment breathing
into a paper bag make sure to have a
spotter for the student who is
breathing into the bag
The Bicarbonate Buffer System
Definitions
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Pulmonary Ventilation is
the movement of air into
and out of the lungs and the
exchange of gases across
the respiratory membrane
The ventilation rate is the
number of breaths per
minute
The pulmonary volume
is the amount of air inhaled
and exhaled with each
breath
Measurement of Relaxed Breathing Rate
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Calculate your lab partner’s
relaxed breathing rate
Have partner read lab
exercise while you count the
number of breaths for 2
minutes.
Divide by 2 = BPM
Record your results
Do this again but have lab
partner do strenuous
exercise for 2 minutes and
then count the number of
breaths.
Pulmonary Volumes
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Pulmonary volumes
are the amount of air that
flows into or out of the
lungs during a particular
event.
Tidal Volume(TV):
amount of air inhaled or
exhaled with each breath
under resting conditions
(300-500ml)
*The numbers given for volumes and
capacities are averages and vary
greatly between individuals
Pulmonary Volumes
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Inspiratory Reserve
Volume (IRV): Amount of
air that can be forcefully
inhaled after a normal tidal
volume inhalation (3100ml)
Expiratory reserve
volume (ERV): amount of
air that can be forcefully
exhaled after a normal tidal
volume exhalation (1200ml)
Residual Volume: Air left in
lungs (1000ml)
Capacities
Lung capacities are
calculated by summation of
volumes
1. Vital Capacity (VC):
Maximum amount of air
that can be exhaled after a
maximal inspiration
(4800ml)
2. Total Lung Capacity
3. Inspiratory Capacity
• Calculate your volumes and
capacities including the
percent of expected VC
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Effect of pCO2 levels on the Respiratory rate
1.
2.
3.
4.
5.
Use our beginning respiratory
rate (unless different lab partner
is being tested)
Have partner take rapid, deep
breaths until they tire (couple
minutes max)
Record the respiratory rate
Then have your lab partner
breathe in and out into a paper
bag for one to two minutes.
Remove bag and record their
respiratory rate on the data
sheets.
Other Exercises
1.
2.
3.
Calculate your minute
ventilation (TV X # of
breaths per min.)
Do flow and resistance
exercise and be able to
describe the relationship
between these.
Listen to your lab
partners respiratory
sounds with the
stethoscope
Cardiopulmonary Resuscitation
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CPR: typically used for
people suffering from a
heart attack (myocardial
infarct), drug overdoses,
drowning or trauma and
obstruction of airways.
Uses chest compressions
of 100 times per minute
on the body of the
sternum.
Physiology of Exercise and
Pulmonary Health
Exercise 41
Exercise
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Aerobic exercises
increase heart rate and
breathing rates at
moderate levels for
extended periods of time.
Anaerobic exercises
result in the consumption
of available oxygen faster
than it can be supplied to
the muscle tissue
Percent Forced Expiratory
Vital Capacity (FEV1/VC%)
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Indications of health can be
roughly correlated with the
amount of air expelled from
the lungs in one second.
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Expressed as a percent when
compared to a person’s vital
capacity (VC).
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Should be approx 75%
Pulmonary Obstruction
COPD = Chronic Obstructive Pulmonary Disease
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Occurs when the
respiratory passages are
narrowed.
Can be caused by excess
mucus (such as asthma) or
inflammation (such as
bronchitis).
Most COPD is caused by
smoking.
VC is normal but FEV1/VC%
is low.
Simply – with obstruction it
takes longer to exhale
Pulmonary Restriction - Fibrosis
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Occurs when the lungs
cannot fully inspire or
expire the full volume of
air - FEV1 is reduced
Vital Capacity (VC) is
reduced
Caused by fibrosis of the
lungs (cystic fibrosis or
from asbestos) or
adhesions of the lung to
the chest (emphysema)
FEV1/VC% is normal
Usually, the cause of pulmonary
fibrosis is the inhalation of
harmful substances.
Possible causes of pulmonary
fibrosis are:
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Inhalation asbestos, rock dust, metal
powder, mold, dust
Tuberculosis (TB).
Severe pneumonia.
Certain medications and poisons.
Irradiation.
Autoimmune diseases.
Sarcoidosis.
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FEV1 Forced Expiratory Volume = volume of air exhaled
under forced conditions in the first one second
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FEV1 /VC Percent Forced Vital Capacity = the ratio of
FEV1 to VC. In healthy adults this should be approximately 70–
85% (declining with age).
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In obstructive lung disease, (asthma, COPD, chronic
bronchitis, emphysema) the FEV1 is reduced because of
increased airway resistance to expiratory flow. Thus, the
FEV1/FVC ratio will be reduced.
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In restrictive lung disease, (fibrosis) the FEV1 and VC are
equally reduced. Thus, the FEV1/VC ratio should be
approximately normal.
Harvard Step Test
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Was developed to determine a
person’s physical fitness.
We do not have the steps
recommended in lab manual but
you can go outside and walk up
and down stairs for 3-5 minutes.
Subject then rests for 30
seconds
Then partner takes pulses every
30 seconds
Calculate PFI using your lab
manual:
Body Mass Index

BMI is a general guide to
fitness
BMI= Weight in
pounds/(height in
inches)2 X 703
or
BMI= Mass(kg)/ Height
(M)2
or
Use chart
Waist/Hip Ratio
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WHR: According to the
American Heart
Association, people who
carry more weight in their
waist region are more at
risk for health problems.
WHR= Circumference of
waist/Circumference of
hips
Lab Activities
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Make sure that you understand today’s activities for the
quiz next week.