Pulm/Renal - Histology - Pulmonary System Flashcards
Of what main type of epithelium is the respiratory tract composed?
Pseudostratified ciliated columnar cells
How many types of cell touch the basement membrane in the respiratory tract?
5
- (ciliated columnar cells,*
- goblet cells,*
- brush cells,*
- small granule cells,*
- basal cells)*
What is the most prevalent cell in the respiratory tract epithelium?
What are the other four types of cell found here?
Pseudostratified columnar cells;
goblet cells,
basal cells,
small granule cells,
brush cells
Goblet cells are full of ________
that mixes with ________
to form _________.
Mucin,
water,
mucus
What type of cell produces the mucus of the respiratory tract?
Goblet cells
You notice prominent goblet cells on a micrograph.
What organ systems could this be?
Respiratory tract;
GI tract
This micrograph shows respiratory tract epithelia.
What is the most abundant cell type?
What cell type is indicated by the arrows?
Pseudostratified columnar cells;
goblet cells
Describe the brush cells of the respiratory tract.
Chemoreceptor columnar cells with microvilli (non-ciliated)
–> interact with afferent nerves on the basal side
(cells indicated by small arrows)
What type of respiratory tract cell is here described:
chemoreceptors and microvilli cover the apical cell, and the cell interacts with afferent nerves on its basal side
Brush cells
(cells with microvilli in image)
What are the neuroendocrine cells of the respiratory tract?
Small granule cells
What are small granule cells (of the respiratory tract)?
Neuroendocrine cells
Which cells of the respiratory tract are small, round progenitor cells found close to the basement membrane?
Basal cells
What is the role of respiratory tract basal cells?
To serve as progenitor cells and support cells
Identify some basal cells in this micrograph of the respiratory tract.
What differentiates the olfactory epithelium of the nasal passage from the rest of the respiratory tract?
- Microvilli on supporting columnar cells
- No goblet cells (Bowman glands instead)
- Olfactory cells (bipolar neurons)
- Nerve bundles
What type of cell is an olfactory cell?
Where are they found?
A bipolar neuron;
the olfactory epithelium of the nasal passages
What type of secretory cell is found in the olfactory epithelium?
Bowman glands
Which are the visceral special senses?
Gustation, olfaction
(chemically activated)
Which are the somatic special senses?
Visual, vestibulocochlear
(mechanically activated)
Olfactory neurons regenerate every ____ - ____ months.
2, 3
What is an example of a neuron type that regenerates often (every 2 - 3 months)?
Olfactory neurons
The nasal cavity is mostly lined with what type of epithelium?
Respiratory (ciliated columnar)
The superior nasal concha is:
The middle nasal concha is:
The inferior nasal concha is:
Part of the ethmoid bone
Part of the ethmoid bone
Its own bone
What effect do odorant substances have on olfactory neurons?
They bind transmembrane chemoreceptors / ion channels to trigger action potentials
What are the swell bodies of the nasal concha?
(to the immediate right of the image cursor)
Collections of vasculature that:
(1) regulate air temp + (2) are erectile tissue
What are some unique factors about the glands of the lamina propria of the nasal olfactory region?
The presence of nerve bundles / Bowman’s glands;
the absence of goblet cells
Where are Bowman’s glands located?
In what layer of tissue?
The olfactory region;
the lamina propria
What is unique about the tissue of the nasopharynx?
Large aggregations of lymphocytes (tonsils)
Define lamina propria.
Connective tissue and glands underlying the epithelium
(separate from the connective tissue of the submucosa)
Define mucosa.
The epithelium
+
the basement membrane
+
the lamina propria
True/false.
Cartilage can be found in the lamina propria.
True/false.
Glands can be found in the lamina propria.
True;
true
Where does the non-keratinized stratified squamous epithelium of the mouth transition to the ciliated columnar epithelium of the respiratory tract?
The larynx
(between the epiglottis, vestibular (false) folds, and vocal (true) folds)
What type of epithelium does this section from the larynx demonstrate?
Respiratory epithelium
(Note the presence of goblet cells)
What type of epithelium is found in the larynx?
Both stratified squamous (non-keratinized) and pseudostratified columnar
(this is a transition point)
What type of epithelium is found on the epiglottis and true vocal cords?
Stratified squamous epithelium
Stratified squamous epithelium is found on which structures in particular in the larynx?
The epiglottis;
the true vocal folds
True/False.
The trachea has a very large number of sero-mucous glands in its lamina propria.
True.
What tissue layer surrounds the entire trachea?
The adventitia
The ends of the C-shaped hyaline cartilage in the trachea are connected by what?
Fibroelastic extensions of perichondrium
Which is the last segment of the respiratory tract to have highly abundant glands in its lamina propria?
The trachea
Describe the cartilage found in bronchi (as opposed to the trachea).
Small, irregular strips
(not C-shaped or continuous)
Most glands located in the bronchi are located in what tissue layer?
The submucosa
Besides size, in what two ways are bronchioles distinct from bronchi?
No cartilage
No glands in the submucosa
How does the epithelium change as bronchioles narrow?
Pseudo-stratified columnar —>
Simple columnar —>
Simple cuboidal
Which cell is present in preceding respiratory segments but not terminal bronchioles?
Which cell replaces it?
Goblet cells,
Club cells (exocrine bronchiolar cells)
How far into the respiratory tract can goblet cells be found?
The bronchioles before the terminal bronchioles
What is the function of Club cells?
How are they shaped?
Progenitor for pneumocytes (I and II), secrete surfactant components, detoxify inhaled substances;
dome-shaped
What type of innervation will cause smooth muscle contraction in the respiratory tract?
Vagal innervation
What type of innervation will cause smooth muscle relaxation in the respiratory tract?
Sympathetic innervation
How does a respiratory bronchiole appear on histology?
Thin layer of cuboidal epithelia + club cells,
a small number of single alveoli
What is the defining feature of respiratory bronchioles that make them respiratory?
The presence of a few single alveolar sacs
The conducting portion of the respiratory tract ends with what structure?
Terminal bronchioles
The respiratory portion of the respiratory tract is made of what structure(s)?
Respiratory bronchioles, alveolar ducts, alveolar sacs
Where are Club (Clara) cells found?
Small bronchioles (terminal + respiratory)
What is an older name for Club cells that is no longer used?
Clara cells
In what segment(s) is(are) goblet cells not found in the respiratory tract?
The terminal bronchioles to the alveoli
What is another name for alveolar macrophages?
Dust cells
How do the alveolar and pulmonary capillary basement membranes interact?
They are fused
Where are Club (Clara) cells found in the respiratory system?
Terminal and respiratory bronchioles
The alveolar connective tissue is a fibroelastic interstitium. What types of fibers are found here?
Collagen, reticular, and elastic
What are the three main components of alveoli?
Pneumocytes (I and II),
fibroelastic interstitium,
pulmonary capillaries
What percentage of the surface area of the lung alveoli is made up of type I pneumocytes?
95%
What percentage of the surface area of the lung alveoli is made up of type II pneumocytes?
5%
What percentage of the cell population of the lung alveoli is made up of type II pneumocytes?
66%
(Note: yet only 5% of the alveolar surface area is made of type II pneumocytes)
Describe the unique structures of type II pneumocytes seen on EM.
Lamellar bodies (striped organelles)
What are the components of surfactant?
Phospholipids (DPPC)
+
4 surfactant proteins (SPA, SPB, SPC, SPD)
Which is the most important surfactant phospholipid?
Dipalmitoyl phosphatidylcholine (DPPC)
Why is the alveolar fibroelastic interstitium important?
It provides the elastance / recoil of the alveoli
What type of cell is here shown?
Hemosiderin-laden macrophages (heart-failure cells) in the lungs
What tissue lines the outside of the lungs?
The visceral pleura
(a small layer of connective tissue + the mesothelium)
Alveolar duct
Alveolus
Blue = Type II pneumocytes
Black = Type I pneumocytes
Green = Capillaries
Note: The blood in the lumen is an artifact of preparation.
A bronchiole
A = respiratory bronchiole
B = branch of pulmonary artery
A = branch of pulmonary artery
B = a bronchiole
Intrapulmonary bronchi
A = Hyaline cartilage
B = Chondrogenic perichondrium
C = Fibrous perichondrium
Identify the indicated structures.
A = Respiratory bronchiole
B = Alveolar duct
C = Atrium
D = Alveolar sac
Note: this is a transverse cross-section.
Larynx;
A = Epiglottis
B = Ventricular fold
C = Vocal fold
D = Thyroid cartilage
Arrow = Vestibule
Yellow bar = olfactory epithelium
A = bone
B = filia olfactoria (olfactory cells)
Black arrows = serous glands
Black bar = Visceral pleura of lung
Black arrows = Mesothelium
A = Respiratory bronchiole
B = Alveolus
C = Branch of pulmonary artery
Blue arrows = Type II pneumocytes
Black arrows = Type I pneumocytes
White arrows = Macrophages
A = Respiratory epithelium
B = Elastic lamina
C = Submucosa
D = Adventitia
(Part of larynx)
A = Ventricle
B = Vocalis muscle
Arrows = Vocalis ligament
What are some of the purposes of the respiratory system?
Conduct / warm / humidify / filter the air
Facilitate gas exchange
Enable speech
Name the four more common bronchogenic carcinomas.
Squamous cell;
adenocarcinoma;
large cell;
small cell
What are two common sources of metastases found in the lungs?
Breast carcinomas;
renal cell carcinoma
What are the two main categories of vascular causes of pulmonary edema?
Hemodynamics (heart failure, volume overload, hypoalbuminemia, etc.);
microvascular injury (infections, aspiration, trauma, transfusion reactions, drug reactions, etc.)
What type of tissue is this?
Is it healthy or diseased?
Lung;
diseased (pulmonary edema)
How does pulmonary edema appear in a micrograph?
- Widened alveoli filled with frothy, pink, proteinaceous transudate
- Capillary congestion
Where do most pulmonary infarctions occur?
The lower lobes (75%)
True/False.
Pulmonary infarcts typically occur as single infarctions.
False.
As many as 50% occur multiply
What shape is a typical pulmonary infarct of the lower lobes?
Wedge-shaped
(apex towards hilum; base towards pleura)
Parallel, gray lines can often be seen in thromboemboli.
What are these lines?
Layers of red cells, platelets, and fibrin
(‘Lines of Zahn’)
The majority of lung infections are caused by ________.
Viruses
What is pulmonary consolidation?
What is a typical cause?
Fluid filling sections of the lung;
pneumonia
What type of tissue is shown in this micrograph?
What is going on with this patient?
Pulmonary tissue;
pneumonia
(neutrophil-rich exudate shown in alveoli)
How does pulmonary tissue appear on histology in a patient with an active tuberculosis infection?
Well-defined granulomas
Caseous necrosis
Several giant cells interspersed
Describe the differences between smokers and non-smokers in terms of small cell, large cell, adeno-, and squamous cell carcinomas.
Most lung cancers are __________ and arise around or near the lung _____.
What carcinoma does not typically follow this pattern and instead arises in the periphery (e.g. from terminal bronchioles)?
Bronchogenic,
hilum;
adenocarcinoma
__ /4 of lung carcinomas arise from first-, second-, or third-order bronchi.
3
Where do lung adenocarcinomas tend to arise?
The periphery
(often from septal cells or terminal bronchioles)
Name the most common general location to find each of the following in the lungs:
Squamous cell carcinoma
Adenocarcinoma
Large cell carcinoma
Small cell carcinoma
Hilum
Periphery
Periphery
Hilum
Which lung cancer is most common in non-smokers or those that have quit smoking?
Adenocarcinomas
Which two hormones can be produced ectopically in which type of lung cancer?
ADH, ACTH;
small cell carcinoma
Where are metastases to the lungs often found within the lungs?
Multiple discrete nodules in the periphery
Carcinomas often spread initially via ___________.
Sarcomas often spread initially via ___________.
Lymphatics;
hematogenous routes
What are two major risk factors for laryngeal carcinomas?
Smoking;
alcohol abuse
(synergistic effects)
Where do laryngeal carcinomas typically arise?
What subtype of carcinomas are they usually?
Directly on the vocal cords;
squamous cell carcinomas (~95%)
What type of histopathology is often seen in cases of squamous cell carcinomas (e.g. laryngeal or pulmonary)?
Infiltrating ‘tongues’ of atypical squamous cells;
squamous pearls
True/False.
Podocytes are essentially a specialized connective tissue cell.
False.
They are specialized epithelial cells.
C.
(fused basal lamina)
