Respiratory (Histo) Flashcards
what are the 2 major division of the respiratory system? what is each of their function?
- Conduction system: to transmit air to lower division while warming, moistening, and removing particulate matter
- Respiratory system: gas exchange between air and blood
what are the 3 major components of the nasal cavity and what is the epithelium found in each?
- Vestibule (inside nostrils) = stratified squamous epithelium, slightly keratinized
- Respiratory portion = pseudostratified columnar epithelium (respiratory epithelium) + cilia (and other cells like goblet cells)
- Olfactory mucosa = super tall pseudostratified columnar WITHOUT goblet cells
what types of cells are found in the nasal cavity epithelium in the respiratory portion?
- ciliated cells
- goblet cells
- basal cells
- neuroendocrine cells of the APUD
- brush cells
what is the function of the ciliated cells in the nasal cavity?
beat synchronously in a posterior direction (TOWARDS oral cavity) in order to move mucus secreted by the goblet cells so that the mucus can trap particulates for filtration
what is the function of goblet cells in the nasal cavity respiratory epithelium?
produce mucus which traps particulate matter
what is the function of basal cells in the nasal cavity?
precursors of other cell types (aka the regenerator cells… for regeneration of damaged/old nasal epithelium)
what is the function of the neuroendocrine cells in the nasal cavity?
secrete small granules ; they are a part of the amine precursor uptake and decarboxylation (APUD) system
what is the function of the brush cells in the nasal cavity epithelium? what structure is characteristic to their function?
have short, blunt, microvilli; function in general sensation.. give you the feeling that you need to sneeze/ticklish nose
What is found in the lamina propria of the nasal cavity ? (underlying the epithelium)
- Loose connective tissue
- Serous and mucus glands
- thin-walled venules
what is the function of the thin walled venules in the lamina propria of the nasal cavity?
warms incoming air due to the arrangement of loops which causes the air to be warmed by blood flowing through the upper parts of the loops;
where is the olfactory mucosa located?
in the roof of each nasal cavity and extends a short distance down over the superior concha and the adjacent nasal septum
describe olfactory mucosa epithelium (histology + what are the cells types)
tall pseudostratified columnar and lacks goblet cells; 4 cell types: 1. supporting (sustentacular cells) 2. basal cells 3. sensory cells 4. Brush cells
describe the the sustentacular cells of the olfactory mucosa (structure and function)
structure: tall cylindrical cells, broad at the apex and narrow at the base; have apical microvilli function : provide metabolic and physical support for olfactory cells
describe the basal cells of the olfactory mucosa (structure and function)
structure = small, conical cells with dark ovoid nuclei function = mitotically active and able to regenerate olfactory function in a few weeks
describe the structure/location of the sensory cells of the olfactory mucosa.
aka bipolar cells
location = between the sustentacular cells; soma is the middle layer of the epithelium
structure =
- spindle shaped with an apical process/ dendrtie which extends to the surface;
- termination of the apical process is in a bulb-like expansion (olfactory vesicle/knob) with 10-20 cilia
- proximal part of the cell extends into the lamina propria as an axon which continue to the olfactory bulb of the brain; the axons are clustered into unmyelinated bundles by glial ensheathing cells;
- cilia contain 350 types of odorant receptors for different odorants
describe the olfactory transduction process
odorant molecules are carried through the air to the mucus in the nasal cavity where they bind to a G-protein eliciting a secondary messenger system through cAMP .. eventually the signal is transduced and reaches the bipolar cell which takes the information to the olfactory nerve to the brain for smell perception
are the neurons of the olfactory mucosa (for smell) ever replaced?
yes; every 30-60 days
what is the function of the brush cells in the olfactory mucosa
have apical microvilli which function in general sensation; they are presynaptic to afferent fibers
Describe the lamina propria of the olfactory mucosa
contains Bowman glands and unmyelinated olfactory nerves en route to cribiform plate to terminate at olfactory bulb
what are Bowman’s glands? what do they secrete? where are they found? where do they secrete their products? ducts?
- found in the lamina propria of the olfactory mucosa;
- produce a watery secretion to trap odorants and moisten and cleanse the surface
- also secrete LYSOZYME and IgA
- deliver their secretions(proteinaceous) via ducts onto the surface of the epithelium
Describe the epithelium of the nasopharynx
lining epithelium is mostly pseudostratified ciliated columnar WITH goblet cells; cilia propel material toward the oropharynx; may be stratified squamous in areas of abrasion
describe the lamina propria of the nasopharynx
contains glands, mostly mucous; abundant lymphatic tissue including the NASOPHARYNGEAL TONSILS (adenoids)
Is there any muscle associated with the nasopharynx?
yes; the pharyngeal constrictors
what are the components of the larynx and what is their general function (ie: respiratory or mechanical).. what type of epithelium can be found in each area?
- ventricular folds = false vocal folds; involved in respiration (respiratory epithelium + mucous/serous glands)
- vocal folds = true; involved in mechanical trauma (stratified squamous epithelium non-keratinized)
Describe the mucosa of the larynx
2 parts:
- PSC respiratory epithelium typically covering the ventricular folds
- non-keratinized stratified squamous epithelium in regions of abrasion (vocal folds)
what is squamous metaplasia?
when the respiratory mucosa of the larynx (PSC epithel) changes to stratified squamous epithelium;
it is generally reversible and in areas of altered air flow, the change may persist
clinically correlated to bronchitis
Describe the components of the submucosa of the larynx
- contains MANY mucus glands, few serous glands
2. the true vocal folds contain a supporting ligament of fibroelastic CT and the skeletal muscle of the vocalis muscle
what supports the wall of the larynx?
hyaline and elastic cartilages; also CT and skeletal muscle
what maintains patency in the trachea?
the cartilagenous rings (~ 20)
describe the mucosa of the trachea
PSC epithelium with a DISTINCT basement membrane and underlying lamina propria
same 4 cells: ciliated epithelium, goblet cells, brush cells, basal cells
describe the ciliated cells of the trachea
most common; propel material UPWARD toward the pharynx in order to protect the lungs from mucus accumulation;
what is chronic bronchitis caused by? what happens in chronic bronchitis?
caused by a loss of cilila from irritation which leads to mucus accumulation in the lungs;
clinical relevance :
- respiratory epithelium changes to stratified squamous epithelim (squamous metaplasia), but the stratified squamous epithelium is not as functionally efficient
- loss of cilia
- removal of mucus is impaired
- coughing as a compensatory means to expel accumulated mucus
- overtime, the number of ciliated cells continuous to DECREASE significantly (cycle can be repeated!)
where are the granules of the neuroendocrine cells located in the trachea? why is there location significant?
located basally and are released into the underlying connective tissue where they provide local regulatory control