1. How the Lungs Work

2. Alveoli
“Air Sacs”
Resemble bunches of grapes
Make up bulk of lungs

5. Respiratory Zone
Includes respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli
Only places where gas exchange occurs

6. Walls of Alveoli
Made of single, thin layer of simple squamous epithelial cells
Covered with a cobweb of pulmonary capillaries

7. Respiratory Membrane Made up of alveolar and capillary walls
Has air flowing on one side, blood flowing on the other
Gas exchange occurs through simple diffusion
Oxygen from alveolar air to capillary blood
Carbon dioxide leaving blood to air
FUN FACT: total surface of alveoli walls is about square meters - about the surface of a tennis court!

10. http://highered. mcgraw- hill
hill.com/sites/ /student_view0/chapter25/animation__ga s_exchange_during_respiration.html

11. Steps to Respiration 1. Pulmonary Ventilation (breathing)
Air move in and out of lungs so alveoli air is refreshed
2. External Respiration
Gas exchange between blood and alveoli air
3. Respiratory Gas Transport
Gas transport between lungs and body by bloodstream
4. Internal Respiration (Cellular Respiration!)
In body, at capillaries, gas exchange between blood and tissue cells

12. Respiration Inspiration Expiration
Air flowing into lungs (breathe in!)
Expiration
Air leaving the lungs (breathe out.)
Volume changes lead to pressure changes, which lead to the flow of gases to equalize the pressure!

13. Inspiration Diaphragm and external intercostals contract
Diaphragm actually moves DOWN when contracts
Thoracic cavity size increases
Rib cage lifts
Intrapulmonary volume increases
Gas molecules spread out due to increased volume! This causes a decrease in pressure, which pulls in more gas.

14. Inspiration

15. Expiration Diaphragm and external intercostals relax
Internal intercostals and abdominal muscles contract if expiration is forced
Thoracic cavity size decrease
Rib cage descends
Intrapulmonary volume decreases
Gas molecules get closer together due to the decrease in volume! This causes an increase in pressure, which forces gas out.

16. Expiration

17. Non-Respiratory Air Movements
Cough
Sneeze
Crying – release of air in short breaths
Laughing – release of air in short breaths
Hiccups
Yawn

18. Lung Development Fetus Birth All respiratory exchange made by placenta
Lungs filled with fluid
Birth
Fluid drained, passageways fill with air
Surfacant: fatty molecule that lines each alveolar sac to prevent from collapsing (don’t have enough of this until fetus is 30 weeks)
Lungs do not fully inflate for 2 weeks after birth
20 to 40 respirations/min

19. Lung Development Teens Elderly
12 to 18 respirations/min (rates differ depending on source)
Continue to develop alveoli (smoking stops this production!)
Elderly
Chest wall becomes rigid, lungs lose elasticity, cilia in trachea less effective
Vital capacity decreases
More at-risk for respiratory tract conditions
18 to 20 respirations/min