Ch+22+23+24+Final+Review+F2015 - The Respiratory System...

22-1
The Respiratory System
Principal Organs:
Nose, pharynx, larynx, trachea, bronchi, lungs
Nasal cavity
Nostril
Hard palate
Larynx
Trachea
Right lung
Posterior nasal aperture
Soft palate
Pharynx
Epiglottis
Esophagus
Left lung
Left main bronchus
Lobar bronchus
Segmental bronchus
Pleural cavity
Pleura
(cut)
Diaphragm

22-2
The Bronchioles -
diameter ≤ 1 mm Pulmonary lobule:
portion of lung ventilated by one bronchiole
Have ciliated cuboidal epithelium
Muscularis Mucosa, well-developed layer of smooth muscle
contracts or relaxes  constrict or dilate airway  regulates airflow
Divides into 50 to 80 terminal bronchioles
•
Final branches of conducting division
•
diameter ≤ 0.5 mm
•
No mucous glands or goblet cells
•
Cilia move mucus draining into them back by mucociliary escalator
•
Each terminal bronchiole splits into 1+ smaller respiratory bronchioles
Respiratory bronchioles
Have alveoli budding from their walls
Mark beginning of respiratory division, because alveoli
participate in gas exchange
Divide into 2 -10 alveolar ducts
End in alveolar sacs : clusters of alveoli arrayed around a central
space called the atrium

22-3
End of Bronchial Tree  Pulmonary Alveoli
Each alveolus surrounded
by basket of capillaries from
pulmonary artery
Which vessel is coming
from Right Ventricle?
Which vessel going to
Left Atrium?

Respiratory Membrane:
Squamous alveolar cell
Shared basement membrane
Capillary endothelial cell
Air
CO
2
O
2
Blood
22-4
Pulmonary Alveoli
Figure 22.12b,c
Squamous alveolar cell
Alveolar
Macrophage
Respiratory membrane
Fluid with surfactant
Great
Alveolar Cell
Lymphocyte
Capillary endothelial cell
Respiratory Membrane - its characteristics are essential in preventing fluid
from accumulating in alveoli - HOW? ...
* Gases diffuse too slowly through liquid to sufficiently aerate blood
* Alveoli kept dry by absorption of excess liquid by blood capillaries
* Lungs have most extensive lymphatic drainage in body
* Low capillary blood pressure prevents rupture of delicate respiratory membrane
Air

22-5
Pulmonary Alveoli in Health and Disease
(a) Normal
Pneumonia
Emphysema
Fluid and blood
cells in alveoli
Alveolar walls
thickened by edema
Confluent alveoli
Figure 22.21
Pneumonia  thickening of
respiratory membrane
Left ventricular failure 
Pulmonary edema 
thickening of respiratory
membrane
Emphysema, lung cancer, and
tuberculosis 

surface area
for gas exchange

22-6
Respiratory airflow is governed by same principles of
flow, pressure, and resistance as blood flow
F   P / R
F = Flow,  P = difference in pressure , R = resistance
Flow of a fluid, e.g., Air, is directly proportional to
pressure difference between two points and
inversely proportional to resistance
Atmospheric pressure drives respiration
this weight of air above us
760 mm Hg at sea level, or 1 atmosphere (1 atm),
but will be l ower at higher elevations

22-7
Resistance to Airflow - F  1/R
Increasing resistance (R) decreases airflow ( F )
Two factors influence airway resistance:
1. Bronchiole diameter, i.e., radius (r)
2. Pulmonary compliance