Surfactant is similar to a detergent, it keeps the fluid coating the lining of the alveoli from creating surface tension. This allows the alveoli to expand without hindrance, and allows greater air flow.
it stunts blood flow from getting to the lungs
Airflow increases when surfactant is applied because the resistance to lung inflation has been reduced.
Trachea
There are no muscles in the lungs that help inhale or exhale, this is the job of the diaphragm.
The flow of blood from the heart to the lungs and back to the heart is called pulmonary circulation.
A mask should be worn any time you're working with harsh chemicals in conditions that don't offer very much air-flow. Or if you have asthma or other issues that affect your lungs.
Air tends to flow into the lungs when thoracic volume increases and pressure decreases. When the opposite is true, air leaves the lungs.
Sperm in the market flow
The term for moving muscles in order to make air flow into and out of the lungs is breathing. The main muscle that moves is the diaphragm, which sits just below the lungs and causes air to flow in and out as it contracts and expands.
It is an alternate way for the blood to flow during fetus development. The alternate blood flow before birth is necessary because the fetal lungs are not yet functioning.
lungs
pulmonary circulation