Lecture 21: Lung Macro & Micro Flashcards
lung lymphatics
white lines under visceral surface, channel lymph towards hilum and mediastinal lymph nodes
pleura composition and components
pleura is made of one layer of mesothelial cells, visceral (inner, intimate with lung) and parietal (outer)
pneumothorax
shrunken lung, associated with air in the pleural cavity
hemothorax
blood in the pleural cavity
sensory innervation of the lung and pleura
vagus nerve, vagus and sympathetic fibers for the visceral pleura, phrenic and intercostal for parietal pleura
vagus nerve in relation to lung position
vagus runs posterior to hilum of lung
phrenic nerve in relation to lung position
phrenic runs anterior to hilum
phrenic nerve diaphragm
provides motor (GSE) fibers to diaphragm
orientation of hilum components on right and left side
On left side artery, bronchi, vein (Are Brides Vain?)
On right side bronchi, artery, vein (You’re Right, Brides Are Vain!)
This is only true at point of exit from the lung, things can cross if the cross section is taken at a different point
Impressions on two lungs
Right lung impressions –> cardiac, azygos vein/arch, S. vena cava, I. vena cava, esophagus, brachiocephalic trunk
Left lung impressions –> cardiac, aortic arch, left subclavian, left brachiocephalic vein
The lungs have a dual blood supply
De-ox. from the pulmonary arteries, ox. from the bronchial arteries that come directly off of the aorta
bronchopulmonary segments
segments corresponding to bronchial tree, there are many of them
tracheobronchial tree components, switch from macro to micro
trachea –> intrapulmonary bronchus (primary/main, secondary/lobar, tertiary/segmental) –>bronchiole –> SHIFT TO MICRO STRUCTURES –> terminal bronchiole, respiratory bronchiole –> alveolar duct –> alveolar sac –> alveolus
components of trachea, outer to inner
adventitia, c-shaped rings, trachealis and longitudinal smooth muscles, submucosa, mucosa
adventita
outer covering of trachea, made of connective tissue
c-shaped rings
hyaline cartilage, incomplete dorsally
trachealis and longitudinal
smooth muscles
submucosa
mucous and serous glands
mucosa
epithelium and lamina propria
Epithelium of the trachea
part of the mucosa, made up of pseudostratified columnar ciliated cells with goblet cells
lamina propria
made up of connective tissue and elastic fibers
purpose of cilia and trachea
move small debri out of respiratory pathway, active movement
other cell types present in trachea epithelium
endocrine (kulchisky) cells secrete seratonin to regulate airway breathing reflex, undifferentiated basal cells
which mainstream bronchii is more verticle
the right one, more likely to choke on the right side
Intrapulmonary bronchus
branches off of trachea, usually next to main branch of pulmonary artery at hilum, made up of smooth muscle, irregular cartilage plates, goblet cells, ciliated pseudostratified columnar cells. Transition to simple ciliated columnar as bronchii get smaller
broncho-pulmonary segment/secondary and tertiary bronchii
branches off intrapulmonary bronchus, travel along side pulmonary artery/arterioles, branch in same pattern, epithelium fully ciliated simple columnar
bronchiole
branches off broncho-pulmonary segment, no cartilage, smooth muscle, very few to no goblet cells, epithelium transitions from ciliated simple columnar to ciliated simple cuboidal
Autonomic innervation of bronchiole glands and smooth muscle
Glands: Sympathetic is inhibiting, Parasympathetic is secretomotor
Bronchiole smooth muscle: Sympathetic is bronchodilation (greater need for O2, fight or flight), parasympathetic is bronchoconstriction
Autonomic innervation of bronchiole and alveolur vasculature
Bronchioles: Sympathetic is vasoconstriction, parasympathetic is vasodilation (maybe, could have no affect)
Alveolar: no affect, capillaries not capable of constriction or dilation. Flow is hormonally regulated
Affects of sympathetics on the lungs
secretory inhibition, bronchiodilation, vasoconstriction
Affects of parasympathetics on lungs
increased secretomotor, bonchioconstriction, maybe vasodilation
pulmonary plexus
cluster of nerve trunks, contains sympathetic and parasympathetic axons, and parasympathetic ganglia
terminal bronchiole
branches off bronchiole, surrounded by layer of smooth muscle, no goblet cells, ciliated simple cuboidal epithelium, clara cells
What are clara cells
Found in terminal bronchiole, precursor to bronchiolar epithelial cells, synthesizes surfactant, inhibits elastin digestion (elastin digestion leads to emphysema), detoxes carcinogens. Contains many secretory vesicles seen on EM. Have a rounded top that bulges above ciliated cuboidal cells
alveolar wall
contains elastin, which stains black on resorcin-fuschin stain
acinus
functional subunit of the lung supplied by a single respiratory bronchiole
respiratory bronchiole
branches off of terminal bronchiole, simple cuboidal epithelium, wall encircled by smooth muscle that is punctured by alveolus, supplies single acinus
alveolar duct
branches off of respiratory bronchiole, a space whose wall is made up of alveolar sacs and alveoli, basically leads towards them from the bronchiole
alveolar sac
terminal part of alveolar duct, contains may alveoli
alveolar capillaries relationship to lumen
protrude into lumen of alveoli, provide more surface area
How wide is blood-air barrier?
.3 microns, alveoli epithelium, basement membrane, endothelium
Alveolar wall cells
Type I pneumocytes –> thin, gas exchange, 40% of cells but 90% of surface
Type II pneumocytes –> thick/bulging, no gas exchange, 60% of cells, replace damaged type I cells, produce surfactant
lamellar bodies
structure inside of type II pneumocytes that creates surfactant, made up of secretory vesicles made of tubular myelin weaves
functions of surfactant
keep alveoli inflated, reduces fluid from from capillaries into alveoli, increases compliance (Stretchability), decreases alveolar surface tension, keeps cell water surface layer thin
alveolar pores
holes in the epithelium surrounding alveoli connecting different alveoli together. equalizes pressure and facilitates flow between acini when a certain bronchiole might be blocked (kind of like collateral circulation)
also called alveolar pore of kohn
function of alveolar macrophages
ingest extra surfactant, also ingest inhaled particulate matter so they have the name “dust cells”
issues in smoker’s lungs
excess carbon particles trapped in macrophages, chronic bronchitis caused by excess mucus production, increased risk for pneumonia, increased risk for emphysema (loss of elastin, fibrosis of tissue), metaplasia (bronchii epithelium changes to stratified squamous), interstitial disease (alveolar walls are thickened), cancer
