Lecture 21: The Lungs Flashcards
what is the R lung divided into
R upper, R middle, R lower (has horizontal and oblique fissure)
what is the L lung divided into
L upper and lower (only oblique fissure)
what is the function of the lung lymphatics
channel lymph towards hilum and to mediastinal lymph nodes
what do the lung lymphatics look like
white lines under shiny visceral surface
what is the pleura composed of in terms of cells
a single layer of mesothelial cells
two types of pleura in lungs and what is in between them
visceral and parietal, pleural cavity is in between
sensory innervation of parietal pleura (receptors, afferent nerve, resulting action)
receptors: tear/puncture
afferent nerve: intercostal and phrenic
resulting action: GSA pain
sensory innervation of visceral pleura (receptors, afferent nerve, resulting action)
rec: tear/puncture
afferent nerve: vagus and sympathetics
result: little/no GVA pain
sensory innervation of smooth muscle (receptors, afferent nerve, resulting action)
receptor: stretch
afferent nerve: vagus
resulting action: herin breuer reflex (limits inspiration)
sensory innervation of mucosa of trachea and bronchi (receptors, afferent nerve, resulting action)
receptor: irritation
afferent nerve: vagus
resulting action: coughing, gasping, prolonged inspiration
sensory innervation of C pain fibers in alveoli and bronchi (receptors, afferent nerve, resulting action)
receptor: inflammation
afferent nerve: vagus
resulting action: stimulates respiration
sensory innervation of pulmonary veins and cardiac plexus (receptors, afferent nerve, resulting action)
receptor: chemical (chemo)
afferent nerve: vagus
resulting action: stimulates respiration if O2 is low
sensory innervation of aortic arch and wall, pulmonary arteries (receptors, afferent nerve, resulting action)
receptor: pressure (baro)
afferent nerve: vagus
resulting action: regulates change in blood pressure
what fibers are in phrenic and where do they go
GSE to diaphragm
what does the pulmonary artery carry
deoxygenated blood
what does the pulmonary vein carry
oxygenated blood
what is the dual blood supply to the lungs
bronchial arteries from aorta, intercostal arteries or subclavian arteries entering at the hilum (oxygenated blood!!!)
pulmonary arteries carry deoxygenated blood!
what do the pulmonary arteries look like
follow bronchial tree to form capillaries around alveoli
what are broncho pulmonary segments
lung sub units corresponding to bronchial tree, no visible lines demarcating these
outline the tracheobronchial tree
trachea to intrapulmonary bronchus
each branch of bronchus has main (1) lobar (2 on R, 3 on L) and bronchioles
what don the bronchioles turn into
terminal bronchioles then respiratory bronchioles then alveolar duct then alveolar sac then alveolus
what separates the trachea (muscle name)
the carina
what is the trachea composed of
Adventitia C-shaped rings – Trachealis & Longitudinal Submucosa Mucosa
what is the adventitia
connective tissue on outside of trachea
what is the c shaped ring
hyaline cartilage in trachea which is incomplete dorsally
what is trachealis and longitudinal
smooth muscles in trachea
what is the submucosa
mucous and serous glands in the trachea
what is the mucosa comprised of
epithelium and lamina propria
what is epithelium in trachea
pseudostratified ciliated columnar and goblet cells
what is the lamina propria in trachea
connective tissue and elastic fibers
what other cells (other than main ones) are present in respiratory epithelium
endocrine (kulchinsky cells) which secrete serotonin etc and regulate airway reflexes (smooth muscle contraction)
also basal cells (not columnar) which are undifferentiated precursors
where do objects lodge
R bronchus (2 parts) more vertical
where is the intrapulmonary bronchus usually located
next to a branch of the pulmonary artery
what types of cells in intrapulmonary bronchus
irregular cartilage plates, smooth muscle, goblet cells, ciliated pseudostratified columnar epithelium, transitions to ciliated simple columnar as bronchi get smaller
what is the bronchopulmonary segment
secondary/tertiary bronchi travel alongside, and branch in parallel with pulmonary arteries/arterioles
what cells in bronchiole
No cartilage, smooth muscle, very few or no goblet cells, epithelium transitions from ciliated simple columnar to ciliated simple cuboidal
what is the autonomic innervation of bronchial glands
sympathetics (inhibitory, 4Fs)
parasympathetic (vagus, secretomotor)
what is the autonomic innervation of bronchial smooth muscle
sympathetic (4Fs, bronchodilation)
Parasympathetic (vagus, bronchoconstriction)
what is notable about bronchi and bronchioles and what is the physiologic result
no gas exchange so want a larger diameter lumen!
sympathetic and parasympathetic function of bronchial vaculature
sympathetic is vasoconstriction
parasympathetic is vasodilation
what is notable about alveolar vasculature
no effect of ANS innervation
function of sympathetics in lungs
secretory inhibition, bronchodilation, vasoconstriction
function of parasympathetics in lungs
secretomotor
bronchoconstriction
vasodilation?
what does the pulmonary plexus contain
contains both sympathetic & parasympathetic axons, and parasympathetic ganglia
*Vagus, L recurrent laryngeal
what are clara cells precursors to
bronchiolar epithelial cells
what is the function of clara cells
detox of carcinogens, synthesizes surfactant like protein, secretes alpha 1 antitrypsin that inhibits digestion of elastin
what happens with elastic tissue breakdown
emphysema
what does the alveolar wall contain
elastic tissue
what is an acinus (acini is plural)
functional subunit of lung supplied by single respiratory bronchiole
what is a resp bronchiole encircled by
smooth muscle
what is interesting about capillary walls
potrude into lumen to provide more surface area
what type of cells are endothelial cells (shape and function)
thin/flat for gas exchange
type I pneumocytes
thin/flat, for gas exchange
what percent of alveolar cells are type I pneumocytes
40% but cover 90% of surface of alveoli
what percent of cells are type II pneumocytes
60%
what is the function of type II pneumocytes
replace damaged type I cells, secrete surfactant
NO GAS EXCHANGE
what are lamellar bodies
secretory vescicles that product surfactant in the form of tubular myelin weaves
where is surfactant found
alveolar surface
what does surfactant do
1) acts as a detergent to decrease alveolar surface tension
2) keeps cell surface water layer thin, increasing gas exchange
3) increases compliance (stretchability)
4) prevents alveolar collapse
5) reduces fluid flow from capillaries into airways
what is surfactant made of
mix of phospohlipids, cholesterol, carbohydrates, proteins
what happens with low surfactant levels
low surfactant levels = respiratory distress syndrome
what do alveolar macrophages do
phagocytose extra surfactant
smokers lungs
XS carbon particules trapped in macrophages
chronic bronchitis as XS mucus from goblet cells
loss of elasticity (emphysema, fibrosis)
what is the cellular change in smokers lungs
metaplasia (bronchi epithelium changes to stratified squamous)
pore of kohn
discrete holes in walls of alveoli
