Histology - Pulmonary / Renal Block 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)
Name the relevant changes in artery from the renal artery to the glomerulus and subsequent capillary beds.
- Renal a. –>*
- segmental a. –>*
- interlobar a. –>*
- arcuate a. –>*
- interlobular a. –>*
- afferent arteriole –>*
glomerulus –>
efferent arteriole –>
peritubular capillaries (cortex)
+
vasa recta (juxtamedullary)
Describe what vessel changes occur after blood passes through the peritubular capillaries (cortical) and/or vasa recta (juxtamedullary).
Either:
Peritubular capillaries (cortical)
Or:
vasa recta (juxtamedullary)
- –>*
- interlobular v. –>*
- arcuate v. –>*
- interlobar v. –>*
- renal v.*
What section of tissue is shown here?
The renal cortex, medullary rays, and medulla
What is a renal corpuscle?
A histological section containing the glomerulus and Bowman’s capsule
What is the order of a nephron?
(See attached image for more detailed description)
Bowman’s capsule –>
PCT –>
Loop of Henle (descending and ascending) –>
DCT –>
Collecting duct
What are some of the general functions of the kidneys?
Waste excretion;
BP regulation;
blood acid-base regulation;
hormone production;
vitamin D production
What is unique about the fenestrated capillaries of the glomerulus?
The lack of a fenestration diaphragm;
presence of a nephrin-containing glomerular slit diaphragm instead
What space can exists between podocyte foot processes (pedicles)?
Filtration slits
What cells form the visceral layer of the glomerular capsule?
What contractile cells are also found in this region?
Podocytes;
mesangial cells
What protein is essential to the glomerular filtration slit diaphragm?
Nephrin
What is the glomerulus in terms of type of blood vessel?
A bed of fenestrated capillaries
In order, what structures must a substrate in a glomerulus pass to reach the lumen of the Bowman’s capsule?
The endothelial fenestrations;
the basement membrane;
the podocyte filtration slit;
the podocyte filtration diaphragm
Which limb of the loop of Henle (ascending or descending) has a thick portion?
Ascending
Describe the epithelial histology of the proximal convoluted tubule and any distinctive characteristics.
Where are they found?
Simple cuboidal layer with brush border,
luminal debris,
indistinct cellular outlines,
very eosinophilic;
the renal cortex and medullary rays
What type of renal tissue is this?
Proximal convoluted tubules
What is the parietal section of the glomerular capsule?
Bowman’s capsule
What are some major proteins and compounds found in the glomerulus basement membrane?
Collagen IV;
fibronectin;
laminin;
heparin sulfate (charge barrier)
True/False.
Albumin can easily pass through the fenestrations / fenestration slits of the glomerulus.
False.
Although albumin can fit through the slits, it is difficult, and the charge barrier helps prevent it from occurring.
How large is albumin in Daltons?
68 kDa
What size proteins can pass through the glomerular filtration slits?
Albumin (68 kDa) or smaller
A mutation in nephrin leads to what condition?
A mutation in collagen IV leads to what condition?
Congenital nephrotic syndrome;
Alport’s syndrome
For what function are the pumps in the thick ascending loop of Henle responsible?
Pumping sodium out of the tubule
Describe the appearance of the loops of Henle vs. collecting ducts on H&E light microscopy.
How is the DCT different on H&E light microscopy when compared to the PCT?
Slightly smaller cuboidal cells;
no brush border;
little debris in lumen;
(still very eosinophilic, still indistinct cellular outlines, still simple cuboidal)
Identify an example of each of the following in this image:
Glomerulus
PCT
DCT
Glomerulus (Purple)
PCT (Blue)
DCT (Green)
The macula densa is on the _____ convoluted tubule and communicates with the ________ arteriole.
Distal;
afferent
The _________ arteriole interacts with the _______ _______ of the distal convoluted tubule.
Afferent;
macula densa
What are the three portions of the juxtaglomerular apparatus?
The macula densa (DCT);
juxtaglomerular smooth muscle cells (afferent arteriole);
extraglomerular mesangial cells (outside the renal corpuscle)
Identify the macula densa and extraglomerular mesangial cells in this image.
(Note: both are part of the juxtaglomerular apparatus.)
What effect does chronic renal disease (e.g. advanced polycystic kidney disease) have on the blood?
Decreased erythropoeitin release –> normocytic anemia
Where, specifically, is erythropoeitin produced?
By what type of cell?
The interstitium surounding the PCT and peritubular capillaries;
interstitial fibroblasts
Which portion of the nephron is involved in vitamin D activation?
Via what enzyme?
The PCT;
1-α hydroxylase
What enzyme is unique to the PCT?
What does it do?
1-α hydroxylase;
turns 25-hydroxy vitamin D3 into 1,25-hydroxy vitamin D3
1-α hydroxylase turns ___(OH) vitamin D3 into ___(OH) vitamin D3 in the ________________ of the kidney.
25-, 1,25-;
proximal convoluted tubule
Activation of 25-(OH) vitamin D3 into 1,25-(OH) vitamin D3 occurs in what organelle(s) of the PCT epithelium?
Via what enzyme?
The mitochondria;
1-α hydroxylase
What process occurs uniquely in the mitochondria of the renal PCT?
Via what enzyme?
Vitamin D activation
(25-(OH) vitamin D3 to 1,25-(OH) vitamin D3);
1-α hydroxylase
True/False.
The conversion of vitamin D from 1,25-(OH) vitamin D to 25-(OH) vitamin D occurs in the PCT via the enzyme 1-α hydroxylase.
False.
The conversion of vitamin D from 25-(OH) vitamin D to 1,25-(OH) vitamin D occurs in the PCT via the enzyme 1-α hydroxylase.
What three stimuli activate the tubuloglomerular feedback system (juxtaglomerular apparatus)?
- Hypovolemia
- Hypotension
- Decreased Na+ in the DCT
What type of epithelium is found in the loop of Henle?
Simple squamous cells
What type of epithelium lines the PCT?
What type of epithelium lines the loop of Henle?
What type of epithelium lines the DCT?
Simple cuboidal, brush border;
simple squamous;
simple cuboidal, no brush border
Describe the histology of the collecting ducts.
Simple cuboidal cells, becoming taller towards the papilla;
clear borders between cells (as opposed to PCT or DCT)
principal cells (light-staining);
intercalated cells (dark-staining)
Identify the renal structures in the image.
1 - Collecting ducts
2 - Loop of Henle
3 - Vasa recta
Describe the urothelium histology.
Transitional epithelium
+
2-3 layers of smooth muscle
+
connective tissue
What is the term used to describe the luminal layer of transitional epithelium in the ureters/bladder/urethra?
Umbrella cells
After passing the loop of Henle, what mechanism is responsible for all further water and ion regulation in the DCT and collecting duct?
Hormonal action
(e.g. aldosterone, ADH)
What structure is this most likely to be?
A ureter
Why is it important that the macula densa (of the juxtaglomerular apparatus) interact with the afferent arteriole?
Filtrate flow is regulated according to the speed / concentration of Na+ in the DCT
Scenario: the macula densa senses a low concentration of NaCl in the DCT.
What does this indicate, and how does the juxtaglomerular apparatus respond?
The flow of filtrate is too slow;
the afferent arteriole relaxes, increasing bloodflow into the glomerulus
What can juxtaglomerular cells (modified smooth muscle) release in response to low blood pressure?
Renin
What organ releases angiotensinogen?
What organ releases renin?
What organ releases angiotensin-converting enzyme?
What organ releases aldosterone?
Liver;
kidney;
lung;
adrenal zona glomerulosa
Describe the portions of the renin-angiotensin system released by each of the following:
Kidney
Lung
Adrenal zona glomerulosa
Liver
Renin
ACE
Aldosterone
Angiotensinogen
What main hormone-releasing functions does angiotensin II perform?
What main vascular and ionic functions does angiotensin II perform?
Stimulates aldosterone synthase in the zona glomerulosa of the adrenal gland;
stimulates ADH release;
stimulates AT1R receptors to cause arteriolar vasoconstriction;
stimulates NaCl reabsorption in the PCT
What main hormone-releasing functions does angiotensin II perform?
Stimulates aldosterone synthase in the zona glomerulosa of the adrenal gland;
stimulates ADH release;
What main vascular and ionic functions does angiotensin II perform?
Stimulates AT1R receptors to cause arteriolar vasoconstriction;
stimulates NaCl reabsorption in the PCT
What location(s) of the nephron is(are) targets for aldosterone?
The ascending limb of the loop of Henle;
the DCT;
the collecting duct
Scenario: the macula densa senses a high concentration of NaCl in the DCT.
What does this indicate, and how does the juxtaglomerular apparatus respond?
The flow of filtrate is too rapid;
the afferent arteriole constricts, reducing bloodflow into the glomerulus
What process is the main regulator for the GFR?
Na+ reaching the macula densa
What location(s) of the nephron is(are) targets for ADH?
The collecting tubule (late DCT) and collecting duct
What are the two main cell types of the collecting ducts?
What general function does each perform?
Principal cells (light-staining) (more) - water reabsorption via aquaporin2 (ADH-regulated)
Intercalated cells (dark-staining) (fewer) - secrete H+ and absorb HCO3-
What is the name of the capillary bed feeding the nephron?
What is the name of the capillary bed surrounding the collecting duct?
What is the name of the capillary bed surrounding the PCT and DCT?
Glomerulus;
vasa recta;
peritubular capillaries
What three structures are characterized by urothelium (transitional epithelium + 2-3 layers smooth muscle + connective tissue)?
The ureters, bladder, and urethra
How long is the average female urethra?
How long is the average male urethra?
5 cm
20 cm
