lecture 17 Flashcards
how does the body create a pressure gradient?
as you inhale your diaphragm drops while your ribcage expands, decreasing volume and lowering the pressure
What is the main factor for pressure gradient during inhalation?
the pressure outside is now greater than inside, so air rushes in
What are the two opposing forces that must be overcome to take a breath?
Stiffness of the lungs
resistance of the airways to the lungs
what is compliance?
the magnitude of the change in lung volume produced by the given change in pressure
What is vital capacity?
lung volume
What is a cause of stiff lungs?
Pulmonary fibrosis
What causes pulmonary fibrosis?
Thickening and scarring of the alveolar membranes can arise from chronic inflammation or exposure to industrial chemicals
What must you overcome to expand the lungs?
the surface tension form thin alveoli walls lined with fluid
What is surfactant?
Major constituent is phospholipids which reduces surface tension in alveoli
What produces surfactant?
Type II pneumocystis
How does surfactant lower surface tension?
Reduces attractive forces between fluid molecules lining alveoli making it easier to increase lung size
Lack of surfactant causes?
Stiff lungs
What is respiratory distress syndrome (RDS)?
when premature infants do not produce surfactant
What force must the air moving to alveoli overcome?
Friction
Where does most of the resistance to airflow arise?
in the bronchi
