Updated New
Flow of air through the respiratory tract
1. nose and mouth
2. pharynx
3. larynx
4. trachea
5. rt/lt primary bronchi
6. secondary bronchi
7. bronchioles
8. alveoli
trends of branching air ways
as the branches increase...
- airways become more numerous
- airways become smaller
- overall cross-sec$onal area increase (Q = vA)
- the speed of air becomes slower
Exchange surface of alveoli
gas flow between alveolar air space to plasma of closely associated capillaries bed
has to pass the alveoli epithelium, the endothelium, and their fused basement membrane
Par$al pressure of gas
Pgas = Patm x % of gas in atmosphere
higher par$al pressure = higher % of that gas
Par$al pressure of gas (w/ water vapor)
Pgas = (Patm - Pwater) x % of gas in atmosphere
Bolye's Law
, P1V1 = P2V2
Bolye's Law: How do lungs fill with air?
Diaphragram contracts -> thoracic V increases -> P decrease (lungs fill with air)
Diaphragram relaxes, -> thoracic V decreases -> P increase (lungs push air out)
lung ven$la$on over $me (terms)
ven$la$on: movement of air into and out of the lungs
residual volume: the volume of air remaining in the lungs a9er breathing out as much as
possible (not 0)
vital capacity: the volume of air remaining in the lungs a9er breathing in as much as possible
$dal volume: the volume of air that moves in or out of the lungs with normal breathing (~500
mL)
types of gas movement in the respiratory system
diffusion: O2 and CO2 move down their own par$al pressure gradient (at alveoli-capillaries
interface and in/out of cells)
convec$on (bulk movement): O2 and CO2 is transported dissolved, bound to hemoglobin (O2
can also dissolved in plasma)
Par$al pressure of gas dissolved in a liquid
At equilibrium, Pgas = Pgas dissolved in liquid
BUT their [O2] in air and [O2] in liquid could be different depending on solubility of O2 in the
liquid
Higher solubility = higher [O2] in liquid
[gas] in solu$on = (Pgas)(solubility of gas)
CO2 is more soluble in water than O2
O2 methods of transporta$on in blood