1. The Respiratory System
Anatomy of - Chapter 23
Physiology of – Chapter 24

2. Functions of the Respiratory System
1. Gas Exchange
2. Filter, warm, humidify
air

3. 3. Regulate pH in the body
4. Sounds and Speech

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,
mucouse 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
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 tissue of lungs recoil) and air pressure in the lungs increases
air moves out to atmosphere due to pressure gradient

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

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

11. -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

12. Pulmonary Volumes- (see lung capacity lab and diagram in text
Pulmonary Volumes- (see lung capacity lab and diagram in text*) know the circled terms

13. Breathing Reflexes- -temporary apnea:
in response to sudden pain, cold, choking
cough/sneeze:
to clear airway

14. Hiccup:
spasm of diaphragm due to pressure on phrenic nerve or sensory nerves in the stomach (air bubble?)
yawn:
????????

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

16. -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 control over breathing vs. CO2
-stretch receptors in lungs tell medulla when lungs are expanded during normal breathing and stop inhalation.

17. 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%)
Other = 7.4 mmHg (.97%)
Pressures of O2 and CO2 in alveoli and blood (mmHg):
Alveolar Air Arterial Blood Venous Blood
P O
P CO

18. 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 97% of hemoglobin in oxygenated blood is oxygen
Saturated
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.