Respiratory System Part 1 Flashcards
Embryologically, respiratory tract originates as outgrowth of the
GI tract
Respiratory system derived from — —
laryngotracheal groove
Develops along — — — — ~ 4th week of development
ventral midline of posterior pharynx
Later develops into — —, an outgrowth of —
respiratory diverticulum
esophagus
Grows into & interacts with surrounding
mesoderm
1’ functions include (3)
air conduction, filtration, & gas exchange
2’ functions include (2)
olfaction (sense of smell) in nasal cavity
& phonation (vocalization—speech) from larynx (voicebox)
Respiration divided into (2)
mechanical respiration & cellular
respiration
Mechanicalrespiration associated with lungs—functions
in
gas exchange (O2 & CO2)
O2 carried to tissues for
cellular respiration (oxidative metabolism => ATP, energy)
Diaphragm
thin, dome-shaped muscle, separates thoracic cavity from abdominal cavity in mammals
With inspiration
intercostal Mm contract, raise ribs; simultaneously, diaphragm contracts (lowers) => increases intrathoracic volume => negative pressure in thorax => inspiration
With expiration
intercostal Mm relax, lower ribs; diaphragm relaxes (raises) => decrease intrathoracic volume => increase intrathoracic pressure => expiration
Pleural cavities lined by
simple, squamous to cuboidal mesothelium
mesothelium overlays thin layer of connective tissue containing
elastic fibers
These two layers collectively referred to as
pleura
Pleura lining thoracic wall is
parietal pleura
parietal pleura is continuous with outer surface of lung as
visceral pleura
Two layers (visceral & parietal) separated by space — — containing — –
pleural space
pleural fluid
pleural fluid acts as — to
lubricant, decrease friction
Pleural space normally contains
partial vacuum resulting in
negative
intrathoracic pressure
pleural space assists with
inspiration
Breach of pleural space results in
pneumothorax
positive intrathoracic pressure, difficulty
breathing & collapsed lung
pneumothorax
Remains unilateral due to
mediastinum
mediastinum
loose connective
tissue layer, separating L & R
hemithoraces
Air enters upper respiratory
tract at
nostrils
nostrils
external
nares
what do external nares open into?
vestibule
Vestibule contains —, help
filter & trap particulate
matter
hairs
hairs are also known as — and incorrectly
called
sinus hairs, vibrissae
Vibrissae are
“sinus
hairs”, meaning the hair
follicle is surrounded by a
blood-filled sinus
Vibrissae
Large sensory hairs, aka
“whiskers” in dogs, cats,
rodents
Air then enters
nasal
cavity
nasal
cavity contains
thin,
scroll-shaped bones,
nasal turbinates/
conchae
nasal cavity is lined with
moist, pseudostratified, ciliated, columnar epithelium
covered by mucus
Nasal cavity also contains
olfactory receptors (bipolar
neurons) for sense of smell;
synapse with olfactory N (CN
I)
Olfactory epithelium also
contains small #’s of
brush
cells
brush
cells
columnar cells with
apical microvilli
Generalized sensory cells of
olfactory & respiratory
epithelia
brush cells
Air then travels into
2
paranasal sinuses &
nasopharynx(series of
interconnected spaces)
Collectively the paranasal sinus and nasopharynx function to (3)
filter,
humidify, & warm inspired air
Nasopharynx connects to
middle ear via
auditory
(Eustacian) tubes
auditory
(Eustacian) tubes allows
equilibration of
air pressure
Entire upper respiratory tract
lined by
pseudostratified, ciliated, columnar epithelium with numerous goblet cells (secrete mucus); aka respiratory epithelium
respiratory epithelium is supported by underlying
lamina propria of loose
connective tissue
Contains numerous glands,
mostly
sero-mucus
Mucociliary ladder
cilia in respiratory epithelium of trachea & bronchi
synchronously beat in metachronal rhythm
Moves surface mucus towards — at rate of ~1 cm/min
larynx
Irritation to upper airways (nasal passages) triggers
sneeze
reflex
Irritation to lower airways (trachea & bronchi) triggers
cough
reflex
Lower respiratory tractbegins at
larynx
Digestive tract intersects with respiratory
system where
upper & lower respiratory
tracts meet at larynx
Opening of esophagus directly behind
opening of
trachea
Normally, — protects trachea during
swallowing
epiglottis
epiglottis
covers opening of larynx
If food enters larynx or trachea, triggers
coughing reflex; may result in
choking
treatment of choking (2)
Heimlich maneuver or emergency
tracheostomy
emergency
tracheostomy
sharp object in jugular/ suprasternal notch
larynx
3 single (thyroid, cricoid & epiglottic) & 3 paired (arytenoid, corniculate & cuneiform) cartilages
the larynx is composed of (2)
hyaline or elastic cartilage
what does the larynx house? (2)
both true & false vocal folds (chords)
where is the larynx located?
below glottis (dorsal opening of larynx)
what is the larynx covered by?
epiglottis
False vocal chords located (2) to true vocal chords
superior & lateral
In addition to —, vocal folds protect lower respiratory tract from
phonation (speech)
entry of foreign bodies
False vocal chords covered by typical — — with associated
respiratory epithelium
sero-mucus glands
most of epiglottis & true vocal chords covered by
stratified, squamous, nonkeratinized epithelium
True vocal chords contain (2)
vocalis M & ligament
Larynx& epiglottis develop from
4th & 6th pharyngeal arches
Larynx is innervated by
branches of vagus(CN X)
Portion derived from 4th arch innervated by
superior laryngeal N
portion derived from 6th arch innervated by
recurrent laryngeal N
Inferior to larynx is
trachea
tracheas lined with
respiratory epithelium with numerous goblet cells & seromucus glands
Trachea supported by C-shaped rings of
hyaline cartilage
C shaped rings of hyaline cartilage face — to facilitate —
caudally
swallowing
Caudal opening contains (2)
connective tissue membrane & smooth M, trachealis M
Trachea subdivides into (3)
1’ or mainstem bronchi
2’or lobar bronchi
3’ or segmental bronchi
Bronchi can be identified by presence of (2)
supporting cartilage rings or plates & accompanying layer of smooth M +/-sero-mucusglands
Cartilage provides support for (3)
larynx, trachea, & bronchi
cartilage prevents
collapse during inspiration
Cartilage absent beyond
3’ bronchi
All bronchi lined by
respiratory epithelium with goblet cells & submucosal seromucus glands
Air in upper respiratory tract, trachea, & bronchi not used for
Air in upper respiratory tract, trachea, & bronchi not used for gas exchange called — — — has average volume of ~150 ml
anatomical dead space
bronchioles sequence
3’ or segmental bronchi bronchioles terminal bronchioles respiratory bronchioles alveolar ducts alveolar sacs/ alveoli— sites of gas exchange, ~ 200 μm in diameter
Bronchioles lack (2)
cartilage &
sero-mucus glands
--- --- performs support function instead; several levels
smooth
Mm
As bronchioles get smaller, general trend towards thinning of
— with loss of — —
epithelium, goblet cells
Terminal bronchioles possess
tall, pseudostratified, ciliated,
columnar epithelium
Respiratory bronchioles possess
simple, cuboidal to
columnar, ciliated & non-ciliated epithelium with occasional
alveoli
Gas exchange begins at level of
respiratory bronchioles
— — contain numerous alveoli lined with simple,
squamous epithelium
Alveolar ducts
In terminal & respiratory bronchioles, goblet cells are replaced by
Clara cells
Clara cells
non-ciliated, dome-shaped, cuboidal to columnar cells
what do the bronchioles produce
lipoproteins, 1’ components of surfactant within airways
what do lipoproteins prevent
sticking together of bronchiole walls
bronchioles also function as
reserve stem cells capable of differentiating into other respiratory cells following damage
— — are scattered throughout respiratory tract
Kulchitsky or K cells
Part of diffuse enteroendocrine system—secrete various
GI hormones
Historical remnants of
evolutionary origins from gut
Also small #’s of — —
brush cells
brush cells
generalized sensory cells (columnar, with apical microvilli)