Intro Flashcards
Type of cells at respiratory epithelium?
Pseudostratefied columnar epithelium
Goblet cells
Make mucus
Type II pneumocytes
Divide to become type II pneumocytes, but also make surfactant
Difference between bronchus histology and bronchiole histology
Bronchus is cartilagenous.
Bronchiole is noncartilagenous
Blood air barrier
Fused basement membranes of alveolus and capillary.
Interstitium
Space between epithelial basement membrane and vascular basement membrane.
Type I pneumocytes
Cover 95% of the surface area but only represent 40% of the cells. Cannot divide
Type II pneumocytes
Cover 5% of the surface area but account for 60% of the cells
Pulmonary vasculature
Is dual:
Pulm arteries: low pressure, has capacitance, gas exchange
bronchial arteries: systemic pressure, supply nutrients to parenchyma.
Structure of pulmonary arteries
Thinner and wider than systemic counterparts due to low pressure
How does size of particulate matter from environmental exposure matter?
Greater than 10 microns get filtered in nose/nasopharynx
5-10 microns get trapped in mucous coating in airways
<2 microns can reach alveolar air spaces.
Minute respiration = ?
Tidal volume * RR
Vt * RR
Normal tidal volume?
450-500 ml
Normal RR is 12-14 breaths/minute
Normal minute ventilation
~6 liters/min
Alveolar respiration = ?
Minute ventilation - dead space ventilation
or
Va = (Vt-Vd) * RR
Physiologic dead space?
The total volume of lungs that does not participate in gas exchange.
Equals anatomic dead space (structures north of respiratory bronchioles) and functional dead space (any alveoli that arent participating in gas exchange)
Normally physiologic dead space = anatomic dead space.
How to measure dead space?
Assuming that arterial CO2 is equal to alveolar CO2…
Vd = Vt * [(PaCO2-PeCO2)/PaCO2]
Relationship between alveolar ventilation and alveolar CO2 content assuming production of CO2 is constant.
Inverse relationship of alveolar ventilation and alveolar CO2 content.
Breathe more, alveolar CO2 decreases. Breathe less, alveolar CO2 increases
Equation for relating alveolar ventilation to partial pressure of alveolar CO2
Va = (VCO2 * K) /PACO2
What happens if the production of CO2 doubles?
Ventilation will increase to maintain PACO2
What does the alveolar gas equation describe?
Describes the relationship between alveolar PCO2 and PO2
Alveolar Gas Equation
PAO2 = PIO2 - (PACO2/R)
R=0.8
Why is R=.8 in the alveolar gas euqation
Because rate of CO2 production is only 80% the rate of O2 consumption
How to determine alveolar concentration of CO2?
Assume its equal to the partial pressure of CO2 in the arterioles.