PULMONARY 01: FUNCTIONAL ANATOMY Flashcards
Main purposes of the upper airways
Filtration, warmth, and humidity of air
Main zones of airways
Conducting zone, respiratory zone
Conducting zone is also called “anatomical dead space,” what does this mean?
There is no gas exchange occurring here
Bronchi vs bronchioles - which has cartilage?
Bronchi have cartilage, bronchioles do not
What is the volume of the anatomical dead space and how does this compare to total lung capacity?
It is about 150mL
Total lung capacity is about 5L
What is the volume of the respiratory region?
2.5-3L
What is the surface area of the respiratory region
50-100m^2
~750sqft (average apt in chicago area)
What is the broncho-pulmonary segment?
The functional anatomical unit
What is the respiratory segment
Composed of the respiratory bronchi and alveolar ducts, this is the physiological unit
How does the composition of alveoli capillary networks contribute to gas exchange?
The alveoli capillaries are extremely thin which allows for gas diffusion
Why don’t alveoli collapse due to Laplace’s law?
Because of surfactant, which reduces surface tension, interdependence (collateral ventilation, mechanical tethering stabilizing alveoli)
Law of Laplace
Magnitude of inward directed pressure in a bubble (alveolus) = (2x Surface tension(T))/Radius of alveolus
What is the normal conclusion based on the Law of Laplace, regarding the stability of alveoli?
You would typically expect small alveoli to collapse due to small pressure and high tension, and that large bubbles would become over-distended
Why do alveoli not collapse (primarily)
Surfactant
Interdependence
What produces surfactant?
Type II cells
What is the surfactnat
It is a lipoprotein complex (phospholipids, surfactant-associated proteins, neutral lipids)
How does surfactant break up surface tension
Smaller alveli are more affected than bigger ones, so it has less impact on larger alveoli. It normalizes inward directed force by breaking up some of that fluid-generated water pressure.
What does surfactant allow for as far as filling rates?
It allows for small and large alveoli to fill at similar rates
What is interdependence with regard to alveoli?
Mechanical tethering and collateral ventilation supporting the structural integrity of the alveoli
What is the mechanical tethering aspect of interdependence?
The tendency to collapse of alveoli is put off by tethering to neighboring alveoli; if one alveoli wants to get smaller (collapse) the others stop it, because they want to get bigger. thus, if one gets smaller, the others provide resistive force.
What is the collateral ventilation stability of alveoli? (MLK)
This is the connections of neighboring alveoli. This is done through the MLK system:
M: Martin channels which connect neighboring bronchioles
L: Lambert channels which connect bronchioles to the alveoli that neighbor it
K: Kohn (pores of Kohn) which connect alveoli together
What are the two circulatory systems that feed the lungs?
Bronchial (systemic) and pulmonary (deox blood from RV)
What is the largest vascular bed in the body?
The pulmonary circulation (the circulation from the RV)
What is the role of the lungs in the RAAS system?
The lungs has ACE which will convert Angiotensin I to active Angiotensin II
