1. THE MECHANICS OF BREATHING

2. BREATHING Breathing change in air pressure in lungs
Air moves from high pressure to low pressure

3. BREATHING controlled by two major muscles:
Intercostal muscles - between ribs
Diaphragm – below chest cavity

4. INSPIRATION (INHALING)
diaphragm contracts & moves down
intercostals pull up and out
increases the volume of the chest cavity
lowers pressure in lungs
air rushes in through nose & mouth to fill alveoli

5. EXPIRATION (EXHALING)
diaphragm and intercostals relax
ribs are pulled down and inward
Creates increased pressure in lungs
air to rushes out
respiratory pearson.notebook

7. LUNG CAPACITY
regular breathing does not use the full capacity of lungs
have reserves for various situation.

8. LUNG CAPACITY

9. LUNG CAPACITY
Tidal Volume (TV)– volume of inhaled and exhaled in a normal breath. Inspiratory Reserve Volume (IRV) – additional volume that can be taken in Expiratory Reserve Volume (ERV) – additional volume that can be forced out

10. LUNG CAPACITY
Vital Capacity (VC) – total volume of gas that can be moved in or out of the lungs
VC = TV+IRV+ERV
Residual Volume (RV) – amount remaining after a full exhalation
prevents lungs from collapsing
Total Lung Capacity (TLC) – total volume in lungs at one time

11. Regulation of Breathing
usually unconscious
brain sends nerve impulse to muscles to contract/relax
controlled by CO2 levels in blood
CO2 diffuses into plasma in blood
forms H2CO3 in water

12. build up of H2CO3 lowers blood pH
causes brain to send impulse to increase BR so CO2 gets exhaled
Homeostasis – maintaining internal stable conditions