1. STUDY Lesson 13 Gas Exchange 1
AIM: How have mechanisms for gas exchange evolved?
DO NOW: Go over pp
HW: Read Ch. 34 pp. 698 – 702
STUDY

2. Basic Vocab Respiration vs. gas exchange Respiratory surface
Respiratory medium (air vs. water)
Ventilation
Countercurrent mechanism
Positive vs negative pressure breathing
Form fits function (alveolus)
Simple diffusion
Air vs. water – discuss amount of O2 that dissolves in each

3. Terrestrial Organisms
Problem of desiccation
Need respiratory organs w/i the organism’s body
Evolution of lungs from swim bladder of fish

4. Respiratory Surfaces Must maximize diffusion: Thin Large surface area
Moist

5. Adaptations for Gas Exchange
Monera, Protista,
Porifera,
Cnidaria
Platyhel-minthes
Anneli-da
(Earth-worms)
Arthropoda (grasshop-per)
Fish
Amphibia
Mammalia & Aves

6. Countercurrent mechanism (Water flows over O2-rich blood first.)

7. Mammalian Lungs (Negative Pressure Breathing)

8. Negative Pressure Breathing
deep breath  contraction of rib muscles   volume of rib cage   P in lungs  air rushing from area of high P (outside body) to the area of lower P (inside lungs).

9. Gas exchange in humans:
Nose  pharynx  larynx  trachea  bronchi  bronchioles  alveoli
V of lungs  P  air rushing in by bulk flow
Negative pressure breathing

10. Alveolus: Form Fits Function
Discuss lipid bilayer with hydrophobic internal area in re diffusion of O2 and CO2

11. How O2 and CO2 enter/exit the blood: diffusion between capillary & alveolus

12. Diseases of the Respiratory System
Pharyngitis
Laryngitis
Bronchitis
Pneumonia
Asthma
Cystic fibrosis
Emphysema (COPD)
Lung cancer