Histology of Respiratory System Flashcards
T/F: mucosa includes lamina/tunica propria
TRUE: mucosa (mucous membranes) include adjacent connective tissue
lamina propria is relatively loose connective tissue with abundant vessels/nerves/lymphatic vessels
T/F: MALT can be just a small group of lymphocytes or a developed lymphatic nodule complete with a germinal center
TRUE: mucosal associated lymphoid tissue can be small group of lymphocytes/plasma cells/neutrophils or developed lymphatic nodule with germinal center
what makes up the conduction portion of the respiratory system?
conduction portion: no gas exchange, warms/moistens inspired air
nasal cavity —> nasopharynx —> pharynx —> larynx —> trachea —> primary, secondary, tertiary (segmental) bronchi —> terminal bronchioles
what makes up the respiratory portion of the respiratory system?
respiratory portion: where gas exchange occurs
respiratory bronchioles —> alveolar ducts —> alveolar sacs —> alveoli
the nasal cavity warms/moistens inspired air by passing it over the _____
nasal conchae (turbinate bones)
what type of epithelium is found in the mucosa of the nasal cavity?
pseudostratified columnar with goblet cells and cilia (“respiratory epithelium”)
lamina propria is highly vascular (think of how easy it is to get a nose bleed!) - “swell body”
what nerves (3) are found in the nasal cavity?
- olfactory bulb/nerve
- ophthalmic division of trigeminal
- maxillary division of trigeminal
olfactory receptor cells are ____ neurons with ciliated dendritic processes that are bathed in serous secretion from ________ in the lamina propria
olfactory receptor cells are BIPOLAR neurons with ciliated dendritic processes that are bathed in serous secretion from BOWMAN’s GLANDS in the lamina propria
how do olfactory receptor cells become depolarized?
olfactory receptor cells: bipolar neurons with ciliated dendritic processes (bathed by Bowman’s glands)
odor molecules dissolve in serous fluid, bind to odorant binding proteins which trigger GPCR on the cilia —> adenyl cyclase-cAMP pathway causes ion channels to open —> depolarization
axons carry impulse to olfactory nerves and on to CNS
after olfactory receptor cells (bipolar neurons) are depolarized, what do the axons have to traverse to reach the olfactory bulb? (in order)
- olfactory epithelium
- ethmoid bone
- dura mater
- arachnoid mater
- pia mater
what is the role of sustentacular cells in olfactory mucosa?
sustentacular cells: nourish olfactory receptor cells
*note that basal cells (stem cells) replace both receptor cells and sustentacular cells
what are the key differences between the respiratory epithelium of the nasal cavity and the olfactory mucosa?
respiratory epithelium - contains goblet cells
olfactory mucosa - contains sustentacular cells and receptor cells, thicker
what are the 3 layers found in both the trachea and bronchi?
- mucosa (respiratory epithelium + lamina propria): abundant BALT
- submucosa: serous and mucous glands
- adventitia: hyaline cartilage and smooth muscle
explain why patients with cystic fibrosis cannot clear mucus
mutation in CFTR (cystic fibrosis transmembrane regulator) —> cannot excrete chloride (component of salt) —> water is not attracted to cell surface —> mucus is too sticky to be cleared by mucociliary escalator
DNES cells in the respiratory epithelium do what?
DNES cells (diffuse neuroendocrine system cells), aka small granule cells or Kulchitsky cells/ K cells
secrete neuropeptides and vasoactive substances into lamina propria
what is different histologically about the pulmonary arteries relative to other arteries?
relatively thin wall
where are Clara cells found and what do they do (3)?
Clara cells: dome-shaped, non-ciliated cells in the smallest bronchioles
secrete lipoprotein to reduce surface tension in the airways, metabolize foreign materials, serve as stem cells
how does the epithelium change from terminal bronchioles to respiratory bronchioles, the first element to participate in gas exchange?
transition from ciliated cells to Clara cells
Type I vs Type II pneumocytes
Type I pneumocytes (95%): squamous cells, gas exchange, joined by tight junctions
Type II pneumocytes: dome shaped, lamellar bodies contain surfactant
what is the blood-air barrier in the lungs composed of (3)?
- type I pneumocytes
- continuous capillary endothelium
- shared basement membrane
what causes respiratory distress syndrome in premature infants?
aka Hyaline Membrane Disease
premature infants do not have enough mature Type II pneumocytes - too little surfactant hinders respiratory function
disease characterized by destruction of tissue distal to the terminal bronchioles
emphysema
elastic fibers esp. affected
(tissue distal to terminal bronchioles is beginning of respiratory portion)
what causes airways to collapse during expiration in emphysema?
low level of alpha1-antitrypsin function or elastase (produced by neutrophils) overproduction —> connective tissue damage
small bronchioles/alveoli not supported, pressure changes during expiration cause collapse (obstructive disease)
how does lung tissue with emphysema appear histologically?
larggggggge huuuugggeee spaces between alveoli
just lots of air, can’t stress it enough
