PHIL 1000X Study Guide - Final Guide: Partial Pressure, Unit, Hypoxic Hypoxia
11 May 2018
School
Department
Course
Professor
BLOCK YB
MODULE Y4 - RESPIRATORY PHYSIOLOGY
UNIT 3
Gas Exchange & Transport
Unit Objectives
When you have finished this unit, you should be able to:
1. Explain how partial pressure gradients, surface area, membrane thickness, and diffusion
distance affect the rate of diffusion of oxygen and carbon dioxide.
a. Partial pressure gradients: Gas moves from a region of high partial pressure
to a region of low partial pressure, down a partial pressure gradient
b. Surface area: not a lot of room for O2 to get through
c. Membrane Thickness: Loss of compliance can affect ventilation, Po2
becomes low.
d. Diffusion distance: longer to travel which makes a slower diffusion rate
e. Ficks law:
f. Diffusion rate = SA x Conc. Grad x Mem perm/ Membrane thickness
g. Directly proportional to concentration gradient (Partial pressure)
h. surface area.
i. Inversely proportional to Membrane thickness and diffusion distance
2. Define the solubility of gases.
a. duh
3. Explain how the partial pressure of a gas in solution is determined and its relation to gas
concentration.
a. Henrys law: Amount of gas that dissolves in solution is proportional to the
partial pressure of the gas
b.
c. Concentration of gas in liquid depends on
d. ~ partial pressure of gas
e. ~ Solubility of gas in liquid
4. List the normal values for gas pressures in systemic blood, alveoli, and peripheral tissue.
(Figure 18.2, pg 567).
a. Systemic:
b. < or equal to 44mmhg of Po2
c. > or equal to 46 mmhg of Pco2
d.
e. Alveoli:
f. Po2= 100mmhg
g. Pco2= 40mmhg
h.
i. Peripheral:
j. Po2= 100mmhg
k. Pco2= 46mmhg
5. Describe alveolar-blood gas exchange.
a. Blood has to flow through capillary beds (perfusion) of alveoli to pick up
oxygen.
b.
c. At Rest -
d. apex of lungs have less perfusion - blood pressure is too low to open
e. the arterioles to apex capillaries
f.
g. During Exercise -
h. blood pressure increases enough
i. to open arterioles, complete lung now in use
6. Define hypoxia, hypoxic hypoxia (hypoxemia), anemic hypoxia, ischemic hypoxia, and
histotoxic hypoxia.(See Table 18.1 pg 566)
a. ASTHMA
b. decreased concentration gradient -- decreased diffusion rate
c. Constricted bronchioles
d. Po2 low, Po2 low
e.
f. EMPHYSEMA
g. less exchange surface area due to collapsed alveoli
h. -- decreased diffusion rate
i. Po2 normal or low, Po2 low
j.
k. FIBROTIC LUNG DISEASE
l. thicker alveolar membrane -- decreased diffusion rate
m. alveolar PO2 low if loss of compliance affects
n. ventilation
o. Po2 normal or low, Po2 low
p.
q. PULMONARY EDEMA
r. increased interstitial fluid -- decreased diffusion rate
s. Exchange surface is normal, Po2 normal.
t. Increased diffusion difference means low Po2
