Intro to Pulmonary Flashcards
Structure of the lungs
Right: 3 lobes
Left: 2 lobes
Both have 10 segments, and middle right lobe has corresponding 4+5 segment on left upper lobe
Pores of Kohn
Fenestrations between alveoli
Channels of Lambert
Connection between small bronchioles and alveoli
Channels of Martin
Between bronchioles
How do alveoli form during development?
Septation
Complete by age 8, then grow
Retinoic acid can induce septation, but not much use in older people with emphysema because septation finished
What is the resistance in the pulmonary blood vessels?
Very low resistance in pulmonary blood vessels (1/6 of aorta) in order to get lower pressure in lungs (the lungs can’t stand the high pressure that the body can!)
Also can lower resistance by recruiting more capillaries and putting them in parallel during exercise
P = RQ
Alveolar-capillary membrane
Air of alveoli –> alveoli epithelium –> basement membranes of alveoli and capillary are FUSED! –> capillary endothelium –> lumen of capillary
(Normally, when you’re not at alveolar-capillary membrane, have two separate basement membranes with space in between)
Type I alveolar epithelial cells
Squamous
Broad, flat, 0.1um thick
93% of alveolar lining membrane
Cannot divide
Type II alveolar epithelial cells
Cuboidal
Have microvilli
Located at septal junctions
Secrete surfactant
Can transform into Type 1 cells (responsible for growth and repair)
Type III alveolar brush cells
Cone shaped cells
Dense microvilli
Rare, found in central part of acinus
Unknown function, maybe chemoreceptor
Alveolar macrophages
Arrive via blood as monocytes
Lie within alveolar lining fluid
Have destructive enzymes to combat infection and scavenge foreign bodies (dust)
Function is impaired by tobacco smoke
Clara cells
Non-ciliated
Reside in bronchioles
Contribute to surfactant production
Contain CYP 450 isoenzymes
Mast cells
Located in sub-pleural area
Secrete heparin, histamine, other mediators
Interstitial cells
Fibroblasts (produce collagen and elastin), myocytes, dendritic cells, neurons (in walls of airways)
Non-respiratory functions of the respiratory system
Filtration of particles
Filtration and dissolution of thrombi (microemboli)
Anti-protease
Hormonal (angiotensin I to angiotensin II)
Lipid metabolism (make surfactant)
Acid/base regulation
Immunological protection
Phonation (talking)
Neurotransmitter removal, paracrine removal, histamine release, antioxidase production