what is the alveolar septum?
its the central site for gas exchange, elastic recoil, and disease pathogenesis
how could you describe the anatomy of the capillaries, alveoli, and alveoli septum?
the capillaries are sandwiched between the alveoli and alveoli septum
what are the cell types of the alveoli septum?
- type 1 pneumocytes : gas exchange
- type 2 pneumocytes : production of surfactant
- macrophages
- fibroblasts
what is the role of elastin and collagen found within the septum?
- helps with stretching during inspiration and elastic recoil during expiration and restoring the lungs to its original shape at functional residual capacity
how is the diaphragm connected to the paricardium?
its is connected via the central tendons
what tendinous structure binds the diaphragm to the thoracic vertebrae?
the crura
which nerve/ spinal nerves keep the diaphragm alive?
the phrenic nerve and spinal nerves c3 - c5
what anatomy passes through the diaphragm
IVC, descending aorta, esophagus, lymphatics
during inspiration and expiration what happens to the diaphragm?
inspiration - contracts downward
expiration - relaxes upwards
what are pores of kohn?
alveoli - alveoli connection
why are pores of kohn important?
it helps with the redistribution of air during V/Q mismatch, it can also cause pathogens to move from one alveoli to another. it can help with the movement of surfactant
what are channels of martin?
bronchiole - bronchiole connection
why are channels of martin important?
it helps air to bypass obstructed areas or areas with reduced perfusion
what are channels of lambert?
bronchiole to alveoli connection
what is structural interdependence of alveoli?
alveoli share a septa, which means the expansion or collapse of one alveoli effects its neighbour
how does structural interdependence of alveoli work?
when the outer alveoli is exposed to interpleural pressure/ transpulmonary pressure and the alveoli expands, the septal traction pulls open the neighbouring alveoli in the inner region
how does structural interdependence effect expiration?
during expiration the alveoli pull on each other aiding in uniform emptying and prevents localized collapse and controlled deflation
what is elastic recoil caused by?
- elastin and collagen
- surface tension
- structural interdependence
COMPRESSIVE atelectasis
caused by external pressure on the lungs such as blood, air, fluid, tumour
Resorptive/ obstructive atelactasis
caused by an airway obstruction where no air enters. when this happens oxygen is diffused into the blood and co2 is not diffused out in the same rate which causes a drop in lung volume. this drop in lung volume causes a decrease in alveolar pressure leading to the collapse of the alveoli due to elastic recoil
scarring atelactasis
lung tissues is destroyed and replaced with scar tissue. this can distort and compress adjacent lung tissue
adhesive atelactasis
a deficiency in surfactant. surfactant decreases surface tension, without it the surface tension is too high and leads to a collapse of the alveoli as seen in IRDS
talk about IRDS
- a deficiency of surfactant usually in premature babies <37 weeks gestation
- surfactant starts to be produced in babies at 4 months gestation and is fully matured by term
what are the types of atelactasis?
- COMPRESSIVE
- obstructive
- scarring
- adhesive
