Lecture 24: Thorax III, Microanatomy and development Flashcards
4 layers of trachea
-mucosa
-submucosa
-cartilaginous layer
-adventitia
trachea mucosa: features
-ciliated
-pseudostratified epithelium
-elastic, fiber rich lamina propria
trachea submucosa: features
-denser connective tissue than lamina propria
trachea cartilaginous layer
C shaped hyaline cartilage
trachea adventitia
connective tissue that binds the trachea to adjacent structures
location of lamina propria
between basement membrane and submucosa
3 main types of cells in epithelium: trachea
-goblet
-ciliated
-basal
goblet cells in trachea
-produce mucous coat
-contain mucinogen granules
ciliated cells in trachea
-coordinated swiping motion of mucous coat from farthest passage to larynx
basal cells in trachea
stem cells that differentiate to replace goblet cells and ciliated cells
which cell type is the most numerous in the trachea
ciliated cells
basement membrane: trachea
-thick
-densely packed collagen fibers
lamina propria: 3 features
-loose connective tissue
-very cellular/vascular
-primary immune response
submucosa: trachea
-loose connective tissue (similar appearance to lamina propria)
-diffuse lymphatic tissue and lympathic nodules that extend from lamina propria
-contains large distributing vessels
-contains submucosal glands composed of mucous secreting acinus
trachea cartilages: definition, function
–made of C shaped cartilages
-provide flexibility to tracheal pipe and maintain patency of lumen
organization of cartilage: trachea
-cartilage surrounded by bone tissue and fibroelastic membrane (tracheal muscle)
2 main divisions of trachea
left primary/main bronchus
right primary/main bronchus
main/primary bronchi divide into __________ and when?
-lobar/secondary bronchi
-once entering the hilum
lobar/secondary bronchi divide into ______
segmental/tertiary bronchi
bronchopulmonary segment
segmental/tertiary bronchus + supplied parenchyma
which bronchus is similar to the trachea in appearance
primary
structure/organization of secondary and tertiary bronchi: 5 layers (superficial to deep)
-epithelium (goblet, ciliated, basal cells)
-lamina propria
-smooth muscle
-submucosa
-cartilage
function of smooth muscle in secondary/tertiary bronchi
contract airways
what kind of cells are found within cartilage
chondrocytes
alveolar sacs vs alveoli
sacs are group of alveoli
organization/branching of bronchioles: from trachea to alveoli
trachea –> main/primary bronchus –> lobar/secondary bronchus –> segmental/tertiary bronchus –> terminal bronchiole –> respiratory bronchioles –> alveolar duct –> alveolar sacs –> alveoli
how does epithelium transform within bronchiole (think: cross section of bronchiole)
simple columnar to cuboidal with clara cells
function of clara cells in bronchiole
secrete lipoprotein that prevents luminal adhesion
are cartilage plates absent or present in bronchiole
absent
what is the respiratory portion of the bronchial tree (what 4 structures)
-terminal bronchioles
-respiratory bronchioles
-alveolar ducts
-alveolar sacs
terminal bronchioles: location, function
-most distal of conducting portion
-do not engage in gas exchange
respiratory bronchioles: location, function
-beginning of respiratory portion of bronchial tree
-engage in gas exchange
alveolar ducts: location, features
-surround duct space
-elongated airways with no walls
alveolar sacs: definition/location
spaces that are at the termination of alveolar ducts
alveoli function
increase surface area for gas exchange
what kind of epithelium is respiratory epithelium
ciliated pseudostratified
2 types of cells that line alveoli surface
-pneumocytes I
pneumocytes II
pneumocytes I: features, function
-simple squamous
-extremely thin, compressed nucleus
-line most of alveoli surface (95%)
-form effective barrier between air space and septal wall
pneumocytes II: features, function
-cuboidal cells, rounded nucleus
-line 5% of alveoli surface
-interspersed among pneumocytes I
-secrete surfactant
surfactant
-phospholipids and hydrophobic proteins that reduce surface tension at air-epithelium interface
-prevent collapse of alveoli
which pneuomocyte type secretes surfactant
II
lamellar bodies: function, location
-contain surfactant synthesized from precursors in blood (glucose, fatty acids, amino acids)
-in pneumocytes I and II
interalveolar septum: definition
site of air blood barrier
air blood barrier = (hint: 3 things)
surfactant + pneumocytes I + endothelium
2 regions of interalveolar septum
-thin region
-thick region
thick region of interalveolar septum
contain connective tissue and macrophages
thin region of interalveolar septum
forms air-blood barrier and responsible for most of gas exchange
do alveoli contain macrophages?
yes
where does gas exchange occur
within thin region of interalveolar septum
deoxygenated blood from right heart goes to alveoli via
pulmonary artery
oxygenated blood from left heart goes to airways via
bronchial artery
oxygenated blood returning to left heart via
pulmonary veins
2 anatomical divisions of bronchiole
-conducting
-respiratory
5 structures within conducting division of bronchial tree
-nasal cavities
-larynx
-trachea
-primary bronchi
-bronchial tree
4 structures within respiratory division of bronchial tree
-bronchiole
-alveolar duct
-alveolar sacs
-alveoli
formation/development of terminal bronchioles
foregut and respiratory diverticulum –> bronchi with left and right buds –> trachea + 3 lobar bronchi branch on right and 2 lobar bronchi branch on left –> continued development of segmental and terminal bronchiole
respiratory diverticulum definition
outgrowth from ventral wall of foregut (lung bud)
endoderm gives rise to
epithelium
mesoderm gives rise to (3)
-cartilage
-muscle
-connective tissue
formation of respiratory bronchioles
-further division of terminal bronchioles
-increased vascularization (capillaries)
respiratory bronchioles give rise to
primitive alveoli with pneumocytes I and II
visceral pleura comes from
visceral mesoderm that lines the lungs
parietal pleura comes from
parietal/somatic mesoderm that lines body wall
pleural cavity comes from
intraembryonic body cavity/coelom
what kind of tissues are lungs made of (hint: developmental)
endoderm and mesoderm
when are majority of alveoli formed
during first few years of postnatal life
postnatal maturation of lungs (3)
-breathing movements begin before birth and cause aspiration of amniotic fluid
-when respiration starts at birth, fluid is resorbed by blood and lymph capillaries
-when fluid is resorbed by alveoli, surfactant remains as phospholipid coat to prevent collapse during expiration
