Respiratory Histology Flashcards
What are the two ‘divisions’ of the pulmonary tree?
conducting division and respiratory division
What are the structures associated with the conducting division of the pulmonary tree?
nasal cavities all the way down to terminal bronchioles (includes pharynx, larynx, trachea, 1 bronchi, 2 bronchi, 3 bronchi, bronchioles, and the terminal bronchioles
What are the structures associated with the respiratory division of the pulmonary tree?
respiratory bronchioles, alveolar ducts, alveoli
Where do you see a change from ring shaped to plate shaped cartilage on the pulmonary tree?
intrapulmonary bronchi
What are some distinguishing characteristics of intrapulmonary bronchi?
-cartilage changes from rings to plates-there is lamina propria containing criss-crossing bundles of spirally arranged smooth muscle and elastic fibers -lymphoid tissue becomes more abundant
The mucosa layer of the respiratory system contains what kinds of cells?
ciliated columnar cells, goblet cells, brush (chemosensory) and basal (stem cells for the epithelium) cells, lymphocytes
What layers of the pulmonary tree have epithelium?
ALL layers.
What layers of the pulmonary tree have goblet cells?
all the way down to segmental bronchi (i.e. no terminal bronchi or lower)same abundance all the way until the main bronchi start, then tapers down
What layers of the pulmonary tree have ciliated cells?
all the way down to respiratory bronchioles (i.e. no alveolar ducts or further)same abundance all the way until the terminal bronchi, then tapers down
What layers of the pulmonary tree have glands?
all the way down to segmental bronchi (i.e. no terminal bronchi or lower)same abundance all the way until the lobar bronchi, then tapers down
What layers of the pulmonary tree have hyaline cartilage?
all the way down to segmental bronchi (i.e. no terminal bronchi or lower)tapers down in abundance from the start of the trachea to where it ends
What layers of the pulmonary tree have smooth msucle?
all the way down to alveolar ducts (i.e. no alveolar sacs or further)same abundance all the way until the terminal bronchi, then tapers down
What layers of the pulmonary tree have elastic fibers?
ALL layerssame abundance all the way until the alveolar ducts, then tapers down
How does/can smoking affect the trachea and bronchi in terms of epithelial?
1) smoking can introduce chronic irritants to the PSCC epithelium in these structures.2) chronic irritants can cause the epithelial cells to lose their coordinated patterns, which can impact mucous removal, and eventually chronic coughing as a result3) chronic coughing causes PSCC epithelium to undergo columnar-to-startfied squamous metaplasia (reversible but damaging particularly in trachea)NOTE: squamous cell carcinomas have their origin in metaplastic epithelium
What kinds of characteristics of bronchioles distinguish them?
only the mucosa layers remain (no muscularis externa or adventitia) submucosa layer and its glands are gonefew or no goblet cellshas Clara cells epithelial cells are more cuboidal than columnar (PSCC cells still present)- more so toward terminal bronchiolesmuscularis mucosa is well developed
What do Clara cells secrete in bronchioles?
a surface active agent and clara cell protein (CC16)- if CC16 levels are low, it means there is damage to that part of the bronchiole
What does the muscularis mucosa do in bronchioles?
it is a major player in determining the diameter of the bronchiole (has a high elastic content of smooth muscle)
What is the main kind of epithelial cell in terminal bronchioles?
cuboidal
What is the main kind of epithelial cell in bronchioles?
PSCC (
What kind of epithelium do respiratory bronchioles have?
ciliated cuboidal (very hard to see the cilia because they are small)
Do respiratory bronchioles have smooth muscle and elastic CT?
Yes. They also have clara cells
Alveolar ducts are lined by what?
alveoli and alveolar sacs
the knobs that are part of the lining of alveolar ducts contain what?
smooth muscle, collagen, and elastic fibers
What is the role of the knobs that help line the alveolar ducts?
they help support the structure of the wall
What kinds of cells do alveoli contain?
Type 1 and 2 pneumocytes (aka alveoli cells)macrophages
What do Type 1 pneumocytes do in alveoli?
make up to 95% of the alveolar lining (squamous shaped)
What do Type 2 pneumocytes do in alveoli?
cuboidal shaped (or round)1) they serve as stem cells for type 1 2) They secrete surfactant (to reduce surface tension) and other proteins that contribute to immune function3) make up to 5% of alveoli lining
Which are more numerous, Type 1 or Type 2 peunocytes?
they are present in equal abundance
What is the alveoli septa?
type 1 (and some 2) pneumocytes and their basal lamina and the endothelial and basal lamina of the capillary
What are the two regions of the alveolus?
thick and thin
Where is the thick region of the alveolus and what does it contain?
where fibroblasts, macrophages, and fibers intervene between the epithelium of the alveolus and the capillarycontains type 2 epithelial cells
What happens in the thin layer of the alveolus?
gas exchange
What are the contents of the thin region of the alveolus?
thin layer of surfactanttype 1 epithelial cell and its basal laminaan endothelial cell and its basal lamina(these two basal laminas are often fused)
What to alveoli macrophages do?
aka dust cellsscavenge inhaled particulate matter
How does collateral circulation of alveoli work?
alveolar pores (of Kohn) are in the inter alveolar septa and they allow passage of air to occur between alveoli when normal pathways are constricted
What are the functions of mucosa in the upper respiratory tract?
1) mucus of goblet cells trap particulate matter2) epithelial ciliated cells filter air and carry particulate matter to the oropharynx to swallow or spit out3) warm inhaled air through goblet cells in epithelium and vessels in the lamina propria
