Anatomy & Physiology II
Lab
The Respiratory System: Part B (Physiology)
1. Function of Respiratory Muscles
Match the respiratory muscles to the appropriate muscle function
_E_ 1. elevates 3rd, 4th & 5 th ribs
_G__ 2. elevates the sternum
__D_ 3. depresses ribs
_A__ 4. compress abdominal contents & ↑ abdominal pressure
_F__ 5. elevates 1st & 2nd ribs
_C__ 6. elevates ribs
_B__ 7. main inspiratory muscle
_A_&_D_ 8. 2 muscles used in forced expiration
a) abdominal muscles
b) diaphragm
c) external intercostals
d) internal intercostals
e) pectoralis minor
f) scalenes
g) sternocleidomastoid
2. Lung volumes & Capacities
Label the following lung volumes & capacities on the diagram
Volumes
Capacities
tidal volume
functional residual capacity
D
H
expiratory reserve volume
total lung capacity
B
F
residual volume
vital capacity
C
G
inspiratory reserve volume
inspiratory capacity
A
E
3. Volume & Pressure Changes during Pulmonary Ventilation
Indicate whether the volume or pressure increases or decreases during inspiration & expiration
Volume or Pressure
Thoracic volume
Lung volume
Alveolar (intrapulmonary ) pressure
Inspiration
Increases
Increases
Decreases
Expiration
Decreases
Decreases
Increases
4. a) What is the composition of air that we inspire?
 97% Nitrogen
 20.9% Oxygen
 0.04% Carbon Dioxide
 0.5 Water Vapor
b) Why is the composition of air different inside the alveolus?
 The air inside the alveolus has less oxygen and more CO2 and water vapour. This is because
the inspired air mixes with the residual air left from the previous cycle.
-That air was lower in 02 (some had diffused into the bloodstream) and higher in CO2 (what
had diffused out of the blood).

There is more water vapor in the alveolar air because the air is humidified when it comes in
contact with the mucous membrane.
c) Identify the following gas Laws
Dalton’s
Boyle’s
Henry’s
The total pressure of a gas in a mixture is equal to the sum of the partial
pressures of its individual gases
The pressure of a given quantity of gas is inversely proportional to its volume
The amount of gas that will dissolve in water (ie. plasma) is determined by its
water solubility and its partial pressure
5. Control of Pulmonary ventilation: The Role of Carbon Dioxide
a) What would a normal resting respiratory rate be?
12 breaths per minute (2s inhale 3s exhale)
b) If you were to hold your breath for 30 seconds, after you exhale, how to you think your respiratory
rate might change?
INITIALLY THERE SHOULD BE AN INCREASE IN DEPTH OF BREATHING, THERE WILL
PROBABLY NOT BE A NOTICEABLE INCREASE IN RATE.THIS IS DUE TO MORE NEED TO GET
RID OF THE EXCESS CO2 AS THERE IS NOT AN INCREASED NEED FOR O2 AT REST
c) If you were to perform a “wall squat” for as long as you could, how would that effect respiratory
rate?
IN THEORY, INITIALLY DEPTH WILL INCREASE AND THEN YOU WOULD SEE AN INCREASEIN
RATE.THIS IS BECAUSE OF A SLIGHT INCREASED NEED FOR O2 AND THE INCREAED
LEVELS OF CO2 BEING PRODUCED BY THE CONTRACTING MUSCLES.IN REALITY THE
LONGER THE STANCE IS MAINTAINED YOU WILL OFTEN CONTRACT YOUR ABDOMINALS
AND HOLD YOUR BREATH TO TEY AND MAINTAIN POSITION.
d) If you were to perform some heavier exercise (brisk walk or going up and down stairs) for a couple
of minutes, how would your ventilation change?
DURING EROBIC EXERCISE THERE IS AN INCREASE IN PHYSICAL ACTIVITY AND MUSCLE
CELLS RESPIRE MORE THAN THEY DO WHEN BODY IS AT REST.THE HEART RATE
INCREASES DURING EXERCISE. THE RATE AND DEPTH OF BREATHING INCREASES. THIS
MAKES SURE THAT MORE O2 IS DIFFUSED INTO THE BLOOD AND MORE CARBON DIOXIDE
IS REMOVED FROM IT.
e) Can you explain why your ventilation rate continues to be increased even though you are now
seated at rest? Observe how long it takes to return to normal.
AFTER THE EXERCISES FINISHES THE RATE DOES NOT IMMEDIATELY RETURN TO RESTING
LEVELS.
WE NEED TO REPLACE 02 THAT WAS CONSUMED AND REMOVE CO2.
THIS WASTE GRADUALLY RELEASED OUT OF THE TISSUES INTO THE BLOOD WHERE IF
CAN BE EXPELLED OUT FROM LUNGS.
CO2 CANNOT BE RELEASED ALL AT ONCE AS THE BLOOD WOULD BECOME TOO ACIDIC. AS
THE LEVELS OF CO2 FO DOWN IN THE BLOOD THE BREATHING STARTS TO LOW.