1. 2.1- Structure and Function of the Ventilatory SystemPg

2. Functions of the Respiratory System
1. Gas Exchange
2. Filter, warm, humidify
air
3. Low resistance pathway for airflow

3. 3. Regulate pH in the body –(maintenance of homeostasis)
4. Sounds and Speech
Tuvan Throat Singing

4. Structure- Upper R.S. (above the thorax)
Nose, sinuses, pharynx, larynx
Lower R.S. (in the thorax)
-trachea
-bronchial tree (R&L brochi & brohchioles)
-lungs – 5 lobes:
R&L Superior
R&L Infererior
Middle – RIGHT SIDE ONLY!
-diaphragm

5. Pharynx- pathway of air
Nose- hairs filter air,
mucous moistens and
catches small particles
Pharynx- pathway of air
AND food
Larynx- “voicebox”
contains the epiglottis
which keeps food out of
trachea
vocal chords= fibrous
elastic bands that are
“tuned” with vocal
muscles

6. Trachea and Bronchial Tree- Rigid
“tubing” embedded
with cartilaginous rings
Smooth muscle can constrict these
Lung- bronchial tree
ends in bundles of
microscopic airsacs
called alveoli (300 million of them)
Alveoli are surrounded
by blood capillaries
where gas exchange
occurs
O2 IN and CO2 OUT

7. Inspiration- (Inhalation)
-only contraction of diaphragm is needed but chest elevating muscles may aid during heavy breathing.
muscle contractions increase volume of thorax
greater volume of thoracic cavity lowers air pressure
air moves in from atmosphere due to pressure difference

8. Expiration- (Exhalation)
-only requires relaxation of inspiratory muscles but contraction of abdominals may force expiration
volume of thorax decreases (elastic fibers of lungs recoil) and air pressure in the lungs increases
air moves out to atmosphere due to pressure gradient

9. Pulmonary Volumes- (measured with a spirometer)

10. VO2= The rate at which oxygen is taken in to the body and used
VO2 max= Is an excellent indicator of fitness. Must be measured with special equipment.

11. Regulation of Breathing- -involuntary breathing controlled in primitive part of brainstem (medulla) -may also be controlled voluntarily (cerebrum)but eventually involuntary control takes over

12. CO2 + Water = Carbonic ACID
-chemoreceptors in brain and throughout body send signals about blood pH, CO2, and O2 concentration to medulla - If pH goes down, or CO2 goes up, breathing increases - If pH goes up, or CO2 goes down, breathing decreases
- O2 receptors = less impact on breathing rate vs. CO2
-stretch receptors in lungs tell medulla when lungs are expanded during normal breathing and stop inhalation.

13. Partial Pressure of Gases in a mixture- directly proportional to the percentage of the gas in that mixture
TOTAL atmospheric pressure= 760 mmHg
Nitrogen = 592 mmHg (78%)
Oxygen = 159 mmHg (21%)
Carbon Dioxide = mmHg (.03%)
Pressures of O2 and CO2 in alveoli and blood (mmHg):
Alveolar Air Arterial Blood Venous Blood
O2 =
CO2 =

14. Hemoglobin- Oxygen molecules bind to the Iron containing portion of hemoglobin and some Carbon Dioxide binds with certain amino acids in hemoglobin - “O2 and CO2 sponge”
About 98% of oxygen in the blood is transported by hemoglobin as oxyhemoglobin
Only 20% of hemoglobin carries CO2.
Most CO2 is carried in the plasma and forms carbonic acid with water. Therefore excess CO2 in the blood will cause blood pH to drop.

15. Importance of Surfactants-
-alveolar lining is moist (H2O)
-Because H2O is a polar liquid it has high surface tension (like magnets)
-surface tension of H2O resists expansion of alveoli and can even cause them to collapse

16. -surfactant molecules have polar and nonpolar parts and break up the surface tension

17. -can’t produce surfactant yet -need artificial surfactant and CPAP*
Premature infants:
-can’t produce surfactant yet
-need artificial surfactant and CPAP*
* C.P.A.P.= Continuous Positive Airway Pressure