Summary Pulmonary Ventilation and circulation

Pulmonary Ventilation
Provide O2 to the tissues

• Main Functions of respiration
Remove CO2
By downward or upward
• Lungs can be expanded or contracted; movement of the Diaphragm

Elevation or depression of the ribs


• Normal quiet breathing - by the diaphragm

• Muscles that raise the rib cage Muscles that pull the rib cage downward
1. External intercostals 1. abdominal recti
2. SCM 2. Internal intercostals
3. Anterior serrati
4. Scaleni



• Pleural pressure - pressure of the • Trans pulmonary pressure
fluid in the thin space bw the lung pressure diff bw the alveoli and
pleura and the chest wall pluera. that on the outer surface of the
(Negative) lungs. (Recoil pressure - elastic
forces that tend to collapse the lungs at
respiration)

Compliance of the lungs - extent the lungs will expand for each unit
increase in trans pulmonary pressure- 200 ml of air/cm H2O

• elastic forces of the heart - 1. EF of the lung tissue
2. EF by the surface tension of the fluid
G determined by elastin and
collagen that lines the inside walls of the alveoli

Surfactant -
• surface active agent in water, reduces the surface tension of water.
• Secreted by type II alveolar epi cells.
• Phospholipids reduce the surface tension.