1. Ch 22- Respiration- The Exchange of Gases
Alveoli
Breathing control centers
Bronchi
Bronchioles
Countercurrent exchange
Diaphragm
Emphysema
Gas exchange
Gills
Hemoglobin
Hyperventilating
Larynx
Lungs
Negative pressure breathing
Partial pressure
Pharynx
Respiration
Respiratory surface
Trachea
Tracheae
Tracheoles
Ventilation
Vital capacity
Vocal cords

2. Gas exchange
Gas exchange- interchange of O2 and CO2 between an animal and it’s environment
Mechanisms:
Breathing
Gases transported by circulatory system to body
Tissues take up O2 and release CO2 to the blood
Animals exchange gases through moist body surfaces
Respiratory surfaces- must be wet to function properly, thin for O2 and CO2 to diffuse easily

3. Respiratory Surfaces Entire outer skin- ex: earthworm
Gills- for exchange in water
Opening and closing of mouth and gills allows for increase in gas exchange efficiency (ventilation)
Countercurrent flow of water enhances O2 transfer (80% can be removed!!!)

4. Countercurrent exchange

5. Respiratory Surfaces
Tracheal system- branching air tubes in body (tracheae) opens to outside, narrowest-tracheoles- extend to nearly every cell in body
* terrestrial animals spend less E on getting O2 because air is lighter and has more O2)
Lungs- most terrestrial vertebrates

6. Human respiratory system

7. Human respiratory system
Air enters through nostrils- warmed, humidified and sampled
Pharynx- throat
Larynx- voice box- air rushing over cords creates sound
Trachea- windpipe- has rings of cartilage to maintain open shape
Bronchi- 2 tubes, 1 to each lung
Bronchiole- get thinner and finer branching within lung
Alveoli- air sacs, end of branching, covered in capillaries, where gas exchange takes place
Cilia and mucous throughout system- clean air
Diaphragm- muscle at bottom of chest cavity, facilitates breathing

8. Breathing Alternating inhaling and exhaling
Diaphragm contracts, rib cage expands= air rushes in
Diaphragm relaxes, rib cage lowers= air’s pushed out
Negative pressure breathing- muscle contraction causes lower pressure inside than outside and air rushes in
Vital capacity- max volume of air we can breathe in & out

9. Breathing

10. Controlling Breathing
Pons and medulla oblongata – breathing control center
Nerve signals sent to contract diaphragm and raise ribs by contraction of muscles
Medulla monitors CO2 levels and regulates breathing in response, also monitors blood pH, cerebrospinal fluid and O2 levels in large arteries and when O2 levels in blood are severely decreased
pH decreases when CO2 increases

11. Hyperventilation Shows how control center works
Purge blood of CO2 so there is a temporary signal to stop breathing (b/c of low CO2 levels)

12. Circulation of gases
O2 rich blood in lungs goes to heart to be pumped to body
O2 poor blood in body goes to heart to be pumped to lungs to pick up O2
Gas exchange occurs by diffusion
Hemoglobin- O2 carrier in RBC’s
1 hemoglobin can carry 4 O2 molecules
Fig 22.11A and B in text
CO2 forms H2CO3 (carbonic acid) in RBC’s  it breaks to HCO3- (bicarbonate ion) and H+ (which hemoglobin takes up so that blood doesn’t become acidic)
In lungs- reaction is reversed HCO3- binds with H+ then H2CO3 is converted to CO2 and H2O which is diffused into alveoli

13. CO2 transport in the blood

14. Gas exchange in fetus
Uses placenta for exchange from mothers blood from lungs
Fetal hemoglobin-special type that has higher affinity for O2
At birth – increase in fetus’s CO2 level triggers breathing control center to start breathing

15. Problems in respiratory system
Asthma- bronchi become inflamed due to allergic reaction
Bronchitis- inflammation of bronchi due to pathogens (ex: bacteria)
Smoking!!- cilia and mucous trap particles and sweep them out before reaching alveoli
Macrophages also engulf particles and microorganisms
Smoking destroys cilia and macrophages- allowing toxins to reach alveoli
Fig 22.7A- lung cancer
Emphysema- alveoli become brittle and rupture, decreases gas exchange (not enough oxygen)