Lung Histology Flashcards
Two divisions of the respiratory tract + definitions
conducting zone- pathway taken by inspired air from the mouth and nose to the gas exchange region of the lungs
respiratory zone- gas exchange region
what does the conducting zone consist of?
nasal passages, pharynx, larynx, trachea, bronchi and most of the bronchioles
what does the respiratory zone consist of?
respiratory zone proper, formed of the bronchioles, alveolar ducts and definitive alveoli
anatomical divisions of the respiratory tract + what they consist of
upper respiratory tract- extends down to , including the larynx
lower respiratory tract- trachea, lungs and respiratory tree
epithelia in the nasal passage
pseudostratified columnar epithelium except for the vestibule which shows keratinizing stratified squamous epithelium
what is respiratory type epithelium?
pseudostratified columnar epithelium that is present in the upper respiratorytract
where is the respiratory type not present?
orthopharynx, vocal cords and anterior margins of the epiglottis
what epithelia are present here?
stratified squamous
what supports respiratory epithelia?
lamina propria
what does the lamina propria and epithelia form?
mucous membrane
functions of the mucosa?
warm and humidify inspired air
provide an immunological defense and a ciliary clearing mechanism against infection and inspired particles
provide a sense of smell- olfactory epithelium
what is found beneath the mucosa?
submucosa
what is present in the lamina propria? + functions
blood vessels- warm the surrounding air
elastin- allow recoil
what is secreted? + where from
mucus
submucosal glands in the submucosa
mucus definition
viscous fluid containing glycoproteins
serous components contain immunoglobulins, lysozymes and enzymes directed against bacteria
mucus function
lines the respiratory tract up until the ends of the bronchi
what is present behind the C shape hyaline cartilage in the trachea?
trachealis muscle
cells present in the upper respiratory tract epithelium
cilliated cells + goblet cells
cilliated cells function
move mucus continually towards the pharynx via the muco ciliary escalator
beat upwards and outwards
move inhaled particles, liquids and microorganisms within the viscous layer out of the body
goblet cell function
produce a viscous film containing mucins, Igs, lysozymes and anti proteases which disable bacterial functions
produce mucinogen that becomes hydrated to mucin when released
difference between bronchi and trachea
almost none
difference between bronchi and bronchioles
bronchi contain cartilage in their walls
bronchioles lack cartilage but have smooth muscle in their walls
other bronchiole structures
no submucosal glands
incomplete bundles of smooth muscle form rings
simple columnar epithelium slowly become cuboidal
ciliated cells persist
goblet cells disappear
acini definition
chief unit of lung function capable fo gaseous exchange
consisting of respiratory bronchioles, alveolar ducts and alveoli
what are the respiratory bronchioles also termed? + why?
transitional airways
conduct air (bronchiolar like) but also participate in gaseous exchange (alveolar like)
gross alveoli structure
many sacs
pores of Kohn provide a potential route of communication between alveoli
within septa of adjacent alveolar walls abundant capillaries are present
how many cell types in alveoli epithelium?
three
what cells? + type and how abundant
Type I alveolar cells- squamous, cover most of alveolar wall
Type II alveolar cells- cuboidal, account for less than 10% of alveolar surface
macrophages
other name for alveolar cells
pneumocyte
Type I pneumocyte structure
very thin cystoplasm
stretched over and conform to the shape of capillaries
what do the type 1 pneumocytes and blood vessles form? + structure
blood-air barrier
thin alveolar walls and thin endothelium
basal lamina of each cell fuse together to form a single layer
type II pneumocyte functions
secrete surfactant
surfactant structure
mixture of lipids and proteins
surfactant function
forms a monolayer on the inner alveolar surface and reduces surface tension
prevents the collapsing of alveoli during exhalation
location of alveolar macrophages
abundant within the alveoli, lesser extent in the septa
macrophage function
phagocytes directed against irritants, particulate matter and microorganisms
structure of pulmonary circulation
abundant capillaries within the septa
supported by collagen and elastic fibres
explain cystic fibrosis
autosomal recessive disorder that leads to airway obstruction due to excessive and hyper viscous mucus secretion
mutation in CFTR
leads to chronic lung infection
venous plexus definition
vascular network found in the lamina propria of the nasal cavity that heat inspired air
