10- Introduction of Respiratory Physiology Flashcards
V
Gas volume
Liters (L) or milliliters (ml)
Q
Blood volume
Liters (L) or milliliters (ml)
P
Pressure of a gas, in a gas or in a liquid
Millimeter of mercury (mmHg) (torr)
or
Centimeter of water (cmH2O)
F
Concentration of a gas in a gas phase
Fraction Percent
C
Concentration of a gas in a liquid, either in chemical equilibrium or dissolved
Percent by volume (vol % )or milliequivalent per liter (mEq/L)
S
Saturation of hemoglobin with oxygen
Percentage (%)
f
Breathing frequency
Breaths per minute
Symbol I E A B v c a
Description
Inspired
Expired
Alveolar
Barometric
venous
Capillary
arterial
Eupnea
normal breathing at rest
hyperpnea
increased breathing
hypopnea
decreased breathing
dyspnea
awareness of breathing, uncomfortable breathing
tachypnea
increased frequency of breathing
hyperventilation
breathing in excess of requirements of metabolism resulting in decreased PaCO2
hypoventialation
breathing insufficient for requirements of metabolism resulting in increased PaCO2
hypoxia
reduced oxygen in inspired air
hypoxemia
reduced oxygen in arterial blood
hypercapnia
increased PACO2 or PaCo2
Apnea
cessation of breathing
periodic breathing
alternate periods of increased and decreased breathing
primary function of respiratory system
- Delivery of oxygen from the atmosphere to the tissues
* Delivery of carbon dioxide from the tissues to the atmosphere
Pathway of O2
- Atmosphere to Alveoli
- Alveolar to Pulmonary (passive diffusion depending on pressure differences)
- Capillary Pulmonary to Systemic Capillary (requires energy to move blood from heart to lungs)
- Systemic Capillary to tissues (passive diffusion of O2 in and CO2 out)
Avogadro’s Hypothesis
for all gases, an equal number of molecules in the same space and at the same temperature will exert the same pressure
dalton’s law
in a gas mixture, the pressure exerted by each individual gas in a space is independent of the pressures of the other gases in the mixture
two determinants of pressure
- number of molecules
- temperature
boyles law
As a gas is compressed, its volume decreases in exactly the same proportion as its pressure increases
(P1V1 = P2V2)
Charle’s Law
If the volume of a gas is kept constant, the pressure of the gas is proportional to the temperature.
-temperature determines kinetic energy of these molecules
gas pressure
force created when gas molecules strike an object
PO2 and PCO2 Changes Along Transport Pathway
Atmosphere-Alveolar Changes due to:
- Dead space
- functional residual volume (we dont completely empty lungs with each exhale)
- continuous O2 utilization and CO2 production
PO2 and PCO2 Along Transport Pathway
-PaO2 is slightly less than
P O due to Venous A2
admixture
-Mixed venous PO2 is less than PaO2 due to O2 utilization
Arterial and mixed venous PCO2 values change less than PO2 values
– Differences between the O2 and CO2 dissociation curves
Lungs Determine Alveolar and Arterial Gases
-When hemoglobin is reduced from the normal of
15 to 7 g%, arterial blood gases are normal.
Difference between gas pressure and gas content in blood
- Gas pressure is force created by kinetic energy of dissolved gas molecules striking an object.
- Gas content is total amount in blood which includes dissolved and that bound to hemoglobin which has no kinetic energy.
If lungs are healthy, anemia does not affect PaO2 but decreases O2 content.
Normal
PaO2 = 100 mmHg Hemoglobin = 15 g/100 ml Content = 20 ml/100 ml
Anemic
PaO2 = 100 mmHg
Hemoglobin = 7.5 g/100 ml
Content = 10.0 ml/100 ml
dissolved O2 =
solubility coefficient X PaO2.
hemoglobin bound =
[hemoglobin] X 1.34 X SaO2.
