ICL 1.3: Respiratory Histology Flashcards
what is dermatophagoides pteronyssinus?
common house dust mite!
he eats dead skin cells and we need him for it!
he’s also one of the most potent allergens for bronchiole asthma!
what is bronchial asthma?
hyperresponsive airways leading to episodic reversible bronchoconstriction
immediate phase: bronchospasm (cough, wheeze)
late phase: inflammation, edema, airway remodel
asthma is a chronic inflammatory disorder of the airways likely caused by imbalance between proinflammatory and tissue protective cytokines
what is COPD?
generally thought to be some biased combination of chronic bronchitis (blue bloater) and emphysema (pink puffer)
patients have progressive dyspnea which ranges in severity from mild difficulty to failure
what is are the general functions of the respiratory tract?
PRIMARY
- gas exchange
- ventilation
- external respiration
SECONDARY
- conditions air
- olfaction
- phonation
what are the major divisions of the respiratory tract?
- conduction portion = nasal cavity to bronchioles
2. respiratory portion = respiratory bronchioles, alveolar ducts and sacs –> where external respiration happens
what are the 2 major types of epithelium in the respiratory tract?
- stratified squamous epithelium
usually just in the respiratory tract where the tissue is exposed to constant insult like eating food!
- ciliated pseudostratified epithelium with goblet cells
which cells types are in the respiratory epithelium?
in the pseudo stratified ciliated columnar epithelium there are the following cells joined apically by tight junctions:
1. ciliated columnar cells
- goblet cells
- brush cells
- serious cells
- small granule cells/DNES
what are basal cells?
part of the respitory epithelium
stem cells for goblet cells
what are ciliated columnar cells?
part of the respitory epithelium
they have 300 cilia/cell that beat to form the mucociliary escalator to clear things from the respitory tract
what are brush cells?
part of the respitory epithelium
narrow columnar cells that have a microvillus border
we don’t really know what they do
what are small granule cells?
part of the respitory epithelium
diffuse neuroendocrine cells
important for secreting hormones and biogenic amines that regulate blood flow through the respiratory system
what are serous cells?
part of the respitory epithelium
columnar cells that have a microvillus border electron dense apical granules
they secrete a water substance but we don’t really know their function
what is Kartagener’s Syndrome? how does it effect the respiratory system?
mutation in dynein
primary ciliary dyskinesia (PCD), also called immotile ciliary syndrome or Kartagener’s syndrome, is a rare, ciliopathic, autosomal recessive genetic disorder that causes defects in the action of cilia lining the respiratory tract and sinuses
non-motile cilia can cause symptoms like frequent respiratory infections that can lead to severe lung damage, chronic nasal congestion, frequent sinus infections
they will also have situs inverses and infertility
what are bronchial carcinoid tumors?
a type of gastroenteropancreatic neuroendocrine tumor
females»_space; males
it’s a Kulchitsky cell tumor that is NOT related to smoking
these cells proliferate and metastasize to the liver and dump vasoactive compounds into the circulation – patients will experience flushing, diarrhea and bronchodilation
what are the 3 general layers of tissue in the respiratory tract?
- mucosa + lamina propria = epithelium
- smooth muscle and connective tissue layer
- adventitia with collagen, connective tissue and cartilage
what tissue types are in all the parts of the respitory system all the way down to the alveoli?
- elastic fibers
2. smooth muscles
what are the functions of the conduction portion of the resiratory system?
- airway
- warms
- humidifies
- sanitizes
- olfaction
- phonation
what are the anatomical structures in the nasal cavity?
- external nares = hairs in the nose that help filter particles in the air
- vestibule = keratinized stratified squamous epithelium, sweat and sebaceous glands and hair follicles
the nasal cavity and paranasal sinuses contain standard respiratory epithelium and olfactory epithelium
lamina propria contains seromucus glands to clean and humidify, arterial plexuses and venous sinuses (Swell bodies) to warm and humidify the air!
where is the olfactory epithelium?
the roof of the epithelium
the olfactory cells are able to contact the CN 1 through the cribriform plate to convey information
what are the cell types in the olfactory epithelium?
- thick pseudostratified epithelium with cilia
- basal lamina
- lamina propria = contains Bowmna’s glands
- Bowman’s glands and ducts –> produce a fluid to hydrate olfactory epithelium and wash the stereocilia to get rid of olfactory molecules
- olfactory cells = bipolar neurons with 6-8 very long non-motile cilia decorated with odor receptors
- sustentacular cells = support cells that help electrically isolate the different olfactory cells
- basal cells = they replace both olfactory and sustentacular cells
NO goblet cells!
where are the tonsils located?
oropharynx
the lamina propria of the naso and oropharymx contains lymphoid tissue nodules: pharyngeal tonsils (adenoids) and palatine/lingual tonsils
what cell type is the epiglottis?
it’s part of the oropharynx
this is because when you swallow the tongue pushes down the epiglottis so that food goes down the pharynx – so food is contacting the oropharynx so it has a non-karatinized stratified squamous epithelium due to all this mechanical insult
what cells types are in the nasopharynx?
it contains typical respitory epithelium
what is the larynx?
a laryngeal structure comprised of largely hyaline thyroid, cricoid, arytenoid, corniculate and cuneiform cartilages and largely elastic epiglottis cartilage, elastic vocal cords and skeletal muscle
the larynx is lined with typical respiratory epithelium EXCEPT that covering lingual surface of epiglottis and true vocal folds
what happens to the respitory epithelium in a smoker?
metaplasia
there’s a great expansion of stratified squamous epithelium OR remodeling of the normal epithelium so that you have more goblet cells and less celiated cells = more mucous but less cilia to clear it = smokers cough
how does the structure of bronchi change as they go from primary to tertiary etc.
airways with progressively smaller diameter exhibit less cartilage with an increase in elastic fibers and smooth muscle
how does the tissue structure change in someone with asthma?
- expansion in the number of goblet cells
- thickening of the lamina propria
- congestion of blood
what is the composition of bronchioles?
NO cartilage and NO glands!
they’re smooth muscle arranged in discrete bundles
so you’ve transitioned from pseudostratified columnar with scattered goblet cells to low columnar or cuboidal with or without cilia
what are clara cells?
cells in bronchioles and terminal bronchioles with no cilia
they produce a surfactant = oily substance to reduce surface tension
they also have a detox system to degrade different toxins
super important to bronchiole health!
what cells compose alveoli?
- type I pneumocytes = simple squamous cells where gas exchange occurs
- type II pneumocytes = secrete alveolar fluid containing surfactant and replace type I and II cells
- alveolar dust cells = macrophages
what is acute neonatal respitory distress syndrome?
- surfactant coat is not present or produced in low amounts in a premature infant
- the alveolar surface tension increases
- hypoventilation causes low oxygen and retention of CO2
- pulmonary hypo perfusion
- endothelial cell damage
- fibrin and other proteins form a hyaline membrane exudate
net effect is the reduced ability of gas exchange
what are alveolar macrophages?
scavenger cells derived from blood-borne monocytes
they’re also called dust cells or heart failure cells!
what is emphysema?
abnormal permanent enlargement of the airspaces distal to the terminal bronchiole (alveoli), accompanied by destruction of their walls
reduced elasticity and FEV so you can’t push the air out of the air pockets
associated with heavy cigarette smoking
what are the causes of emphysema?
- protease-antiprotease hypothesis- emphysema results from the destructive effect of high protease (elastase) activity in patients with low antiprotease activity
- homozygous alpha-1-antitrypsin deficiency
- smoking stimulates release of elastase from neutrophils
