Respiratory System Flashcards
functions
- air conduction/transport - alveoli
- conditioning w/ moisture and warmth
- filtration to remove particles/pathogens
- **mechanical **respiration aka exchange b/t air and blood
- reservoir for megakaryocytes maybe
air conduction specifics
- ventilation = move air in/out lungs
- carry olfactory stimuli to receptors in region of nasal cavity
- move air past larynx to generate speech
system components
- extrapulmonary portion of resp tract
- intrapulmonary portion of tract
- CT stroma (divides lungs into lobes)
- visceral + parietal pleura
- muscles of respiration
tract divisions
- conducting (extra + intrapulmonary) for air transport/filtration/conditioning only
- respiratory (alveoli, bronchioles) where gas exchange with blood actually occurs
conducting portion contents
trachea
primary bronchi
secondary bronchi
tertiary bronchi
small bronchi
bronchioles
terminal bronchioles
respiratory portion contents
respirator bronchioles
alveolar duct
alveolar sac
alveolus
tract layers
- mucosa (surface epithelium + lamina propria + musculars mucosae)
- submucosa
- muscularis externa
- adventitia/serosa
not every tract will have every layer
adventitia layer
maybe cartilage usually hyaline but in larynx elastic
keeps large airways patent
submucosa layer
dense irregular fibroelastic CT
maybe seromucous glands
respiratory system mucosa layer
-surface epithelium
-lamina propria
-muscularis (reg diameter of airways via smooth muscle + structure)
acetylcholine causes SM contraction and restrict airways
olfactory region
location
only has olfactory mucosa with epithelium and propria
@periosteum of cribiform plate in ethnoid bone (roof of nasal cavity)
olfactory mucosa histology
- olfactory epithelium- pseudostratified ciliated columnar w/o goblet cells + receptor cells
- lamina propria- LCT + vessles + swell bodies (venous plexus) + nerves aka CN I + bowmans glands (serous, dissolve odorants)
nerves are unmyelinated
cells in olfactory epithelium
- receptor cells w/ dendrite bulb and cilia, bipolar, unmyelinated
- supporting cells/sustentacular aka glial cells
- basal stem cells
- brush cells for general sensory recption via CN V (columnar w/microvilli)
olfactory N
clinical relevance
axons of receptor cells route to CNS so pathogens could bypass BBB>viruses entering olfactory cells can trigger apoptosis
receptor cells are exposed to circulating air in nasal cavity
respiratory epithelium
pseudostratified columnar with
-goblet cells for mucus to trap particles
-ciliated columnar cells to move mucus to mouth, motile
-basal cells for stem
-brush cells for general sensory
-neuroendocrine cells aka kulchitsky to secrete hormones (catecholamines, serotonin, calcitonin) dec after birth
-mast cells and intraepithelial lymphocytes (T)
line most of respiratory tract
mucociliary clearance
if mucus too thick cilia have more diff time clearing it or can’t at all
goblet cells and cilia
nasal cavity/sinuses/nasopharynx
histology
nasal mucosa: LP has
numerous swell bodies
vessels and glands (condition air)
swell bodies rupture in nose bleeds
oral cavity/oropharynx /laryngopharynx
shared with digestive tract
mucosa = nonkeratinized stratified squamous
food more abrasive than air so need thicker epi for protection
larynx
histology
lined by respir epithelium except true vocal cords (nonker strat squamous)
LP = numerous mucous and seromucous glands
no muscularis or submucosa
adventitia = hyaline cartilage except epiglottis is elastic cartilage
epiglottis bends during swallowing then returns to og
trachea and bronchi
mucosa
BM very thick in trachea/primary/secondary bronchi so harder for pathogens to cross
LP has BALT and seromucous glands
muscularis: absent in trachea and primary
-present as cont SM layer in secondary and tertiary
-SM strips in smaller bronchi
BALT
diffuse lymphoid tissue
common in infants > adolescents but in adults only assoc w/ illness or smoking
trachea and bronchi
submucosa
submucosal glands/seromucous
dec in size and number as bronchi get smaller
trachea and bronchi
adventitia
in all bronchi + hyaline cartilage
trachea + primary = C rings with trachealis muscle to contract
2/3/smaller = irregular plates, dec in size
asthma
chronic inflamm disease of intrapulmonary airways (bronchi) so trouble air in and out
first attack b/t 0-6 yr old
triggers: allergens, exercise, breathing cold air
asthma histology changes
bronchospasms irritate mucosa = inc mucus > inflammation
edema and elevated WBC in tissues
repeated attacks = inc # of goblet cells so more mucus and perm thickening of walls esp small bronchi
bronchioles
layers
epithelium = simple cuboidal, no goblet cells, club cells
LP= no glands or balt but lots of elastic fibers
muscularis= thick in all, cont sheets around circumference of largest>strips in terminal/respir
no cartilage
club cells
stem cells and secretion
- surface active agent to prevent luminal adhesion and bronchial walls from collapsing and sticking to walls, soapy
- CC16 antioxidant and antiinflammatory molecule, elevates when bronchioles damage
terminal bronchioles
end of conducting portion
mucosa is solid wall w/o gaps, short simple columnar, no glands, discont muscularis
no submucosa
adventitia = fibroelastic CT
respiratory bronchioles
first airways in respiratory division
walls have alveoli budding off
air flow b/t respir bronchioles directly into alveoli
alveoli
gas exchange occurs w/ continuous capillaries
pores of Kohn: collateral gas circulation b/t adj alveoli if blocked, passageway for macrophages/pathogens
alveolar ducts
no cuboidal epi or SM
have gaps opening into alveoli
terminates in a alveolar sac
cell types in alveolar epithelium
- type I- pneumocytes, gas exchange, 95% of alveolar surface, cannot divide, thin/delicate
- type II- stem cells, secrete surfactant (lipids and proteins) to reduce surface tension from lamellar bodies
associated cells
not in alveolar epi
alveolar macrophages/dust cells
-patrol surface of lumen so not embedded w/i, travel thru pores or burrow into CT
-also patrol CT of alveolar septum
neonatal respiratory distress syndrome
NRDS
type II cells not differentiate until week 22-34, lungs not differentiate until week 35
premature babies (under 28) underdev lungs and type II cells not enough surfactant to prevent collapse
can lead to hypoxemia and metabolic acidosis
interstitium
LP of alveolar wall= pulmonary intersistium
mostly elastic fibers, no glands
-allow to expand during inhalation then relax, passive way of getting air out of alveoli
emphysema
form of COPD (from smoking, pollution)
destruction of elastic fibers in alveolar walls = reduced ability to get air out
neutrophils secrete elastases that destroy fibers so alveoli lose elasticity > walls destroy so less surface area for gas transfer
alveolar septum
2 alveolar epi + BM
+pulmonary interstitium
+cont capillary + BM
epithelium trends
more cell types in larger airways
tall pseudostratified columnar in most of tract > simple squamous in alveoli
alveolar septum
TEM
thin portion= BM of capillary endo fuses with BM of alveolar epi
thick portion= alveolar epi DM sep by interstitium so no fusion
smooth muscle trends
muscularis
1.continous sheets in larger bronchi
2.strips in smaller
3.continuous sheets in largest bronchioles
4.small circumferential strips in terminal and respir bronchioles
5.absent in alveolar ducts/sacs/alveoli
elastic fibers trends
in LP and submucosa
fairly consistent
esp important in alveoli
cartilage trends
adventitia
only in trachea and bronchi
absent in bronchioles and alveoli
blood gas barrier
air-blood
physical barrier includes everything gasses must cross
site of gas transfer to RBCs
prevents bubbles from forming in blood
prevent blood from entering alveoli
