Histology of the Respiratory System: Heinbockel Flashcards
What is the primary function of the respiratory system?
- gas exchange which involves the lungs
- humidifies, cleans, and warms the air
Incoming air goes through which structures? List them in order.
- nasal cavities
- nasopharynx
- larynx
- trachea
- smaller bronchi
- bronchioles
- alveolar ducts
- alveolar sacs
- alveoli
What is the conducting portion of the respiratory system responsible for?
supplying the lungs with air
What is the respiratory portion of the respiratory system responsible for?
site of gas exchange
Alveoli and alveolar ducts and sacs are part of what division of the respiratory system?
respiratory portion
Bronchi, bronchioles, terminal bronchioles are part of what division of the respiratory system?
conducting portion
As air travels from the nose to the alveoli, what happens to the number of glands, cilia, and goblet cells?
- gland number decreases to none
- cilia and goblet cells disappear
As air travels from the nasal cavity to the alveoli, what happens to the number of air passageways, their size, thickness, and rigidity?
- number of air passages increase
- luminal diameter (size) of the air passageways decrease
- decrease in the thickness and rigidity of the wall due to less bone and cartilage
What is the epithelium of the external surface of the nostrils or nares?
keratinized stratified squamous epithelium
Why do individuals often get nosebleeds when impacted on their nose?
the vestibule is highly vascularized (lots of blood vessels)
What is the epithelium of the anterior surface of the nasal cavity?
non-keratinized stratified squamous epithelium
What is the vestibule?
the most anterior part of the nasal cavity
What is the epithelium of the further posterior surface of the nasal cavity?
respiratory epithelium AKA pseudostratified ciliated columnar epithelium with goblet cells AKA PCC
What is the function of the sweat, mucous glands in the vestibule?
goblet cells produce mucus droplets comprised of glycoprotein and is secreted out on the surface of the epithelium to help trap dust particles that get into the nose??
What is responsible for the distinct line on the apical portion of the pseudostratified ciliated columnar epithelium?
basal bodies of the cilia
Describe the composition of cells of the pseudostratified columnar epithelium.
30% ciliated columnar cells
30% goblet cells
30% basal cells
10% endocrine cells (members of the diffuse endocrine system AKA DES AKA bronchial cell of kulchitsky
Which cells undergo mitosis and differentiation in the respiratory epithelium?
basal (short) cells which are generative stem cells
What type of connective tissue is found in the lamina propria?
loose connective tissue
What is the purpose of the superficial venous plexus in the lamina propria?
allows for countercurrent flow to help warm up the air during the cold for example
What type of arrangement does the cilia have in respiratory epithelium?
9 plus 2
What is the function of the cilia in the respiratory epithelium?
to move mucus around the epithelium to get it out of the respiratory system
Cilia have to move the mucous which requires lots of energy (ATP). What organelle will be predominant in the ciliated columnar cells?
mitochondria
What is Kartagener’s syndrome?
AKA immotile cilia syndrome
- the dynein or microtubules are missing; the cilia are not beating properly or moving around anymore: this means the goblet cells will continue to produce mucous which covers the cilia
- this can lead to recurrent chest infection (bacterial) or prolonged stagnation of mucal secretion and bacterial infections leading to a widening or dilation of airways leading to premature death
Describe the the key differences of the olfactory epithelium in comparison to the respiratory epithelium.
- no goblets cells but Bowman’s gland that secrete fluid
- have microvilli at apical portion
- olfactory receptors (bipolar) on the olfactory epithelium to bind to odorant molecules and turn them into electrical signals
- supporting or sustentacular cells, olfactory cells, basal cells
What is the upward flap-like extension of the anterior wall of the larynx?
epiglottis
The anterior surface and upper part of the posterior surface of the epiglottis is covered with what type of epithelium?
stratified squamous nonkeratinized epithelium (lingual surface)
-remember surfaces that are constantly impacted (receiving chemical stress) are most likely stratified squamous
The lower, more protected part of the epiglottis is covered with what type of epithelium?
pseudostratified ciliated columnar epithelium with goblet cells (pharyngeal surface)
What type of cartilage is present in the epiglottis?
elastic cartilage
What is the function of the epiglottis?
closes larynx
What are the types of vocal cords in the larynx and where are they in relation to one another?
false vocal cords are superior to the true vocal cords
What type of epithelium is found in the false and true vocal cords? Is there skeletal muscle present in the false and true vocal cords?
FALSE
- pseudostratified ciliated columnar epithelium
- no skeletal muscle; mostly fat
TRUE
- stratified squamous epithelium
- skeletal muscle beneath this epithelium
What is the function of the stratified squamous epithelium in the true vocal cord?
acts as a protective covering to the skeletal muscle allowing phonation
What changes occur in the epithelium of a chronic smoker?
the pseudostratified ciliated columnar epithelium changes to stratified squamous epithelium to compensate for the continuous mechanical stress the epithelium is exposed to
What is the function of the C-shaped cartilage rings of the trachea? Are they complete or incomplete?
- keep the trachea open so it doesn’t collapse
- incomplete as it is not completely around the trachea
What type of epithelium is found in the trachea?
respiratory epithelium AKA pseudostratified ciliated columnar epithelium with goblet cells
What is the function of the mucociliary escalator?
cilia are beating in a unidirectional manner to move mucus with trapped dirt particles out of the lungs (airways)
What is the name of the smooth muscle that is found posteriorly in the trachea?
trachealis muscle
List the following in order from most superficial to least anterior of the trachea.
- submucosa
- mucosa
- c-shaped ring of cartilage
- c-shaped ring of cartilage
- submucosa with mucous and serous glands
- mucosa is constitutive of the pseudostratified ciliated epithelium with goblets and the lamina propria with a thin layer of connective (loose) and diffuse lymphatic tissue connective tissue
What type of cartilage is found in the trachea?
hyaline cartilage
As there is loss of cartilage as the bronchial progresses, what is there an increase of?
smooth muscle
Where is there a transition from pseudostratified ciliated columnar to non-ciliated simple cuboidal or simple columnar epithelium?
in bronchioles
What is the difference between mucous and serous fluid?
mucus is a thick sticky substance that acts in collecting debris for swallowing
serous fluid is a thinner runny substance that is mainly for keeping the epithelial tissue moist and lubricated
Describe the neural control of airway diameter listing the hormone used.
sympathetic nervous system and adrenal glands release epinephrine to relax smooth muscle and dilate airways
What are the differences in the wall structure of the trachea, bronchus, and bronchiole?
trachea: almost complete cartilage with smooth muscles
- bronchus: broken up cartilage AKA cartilage plates with more smooth muscle in the center
- bronchiole: no cartilage but an abundance of smooth muscle that is complete; lose ciliated and goblet cells
What are the cluster of cells that stain really dark in the wall of the bronchus and digestive system?
- diffuse of nodular lymphatic tissue (bronchus associated lymphoid tissue)
- they deal with foreign material
What is the difference between terminal bronchiole and respiratory bronchiole?
terminal bronchiole: close to bronchus
respiratory bronchiole: close to alveoli
What are the serous secretory cells in the bronchioles and what is their function?
dome-shaped Clara cells which have NO cilia and are present in the epithelial lining secreting GAGs that protect bronchiolar lining
What is the purpose of chloride transport in Clara cells?
Clara cells have chloride channels that secrete chloride onto the surface of the epithelium which allows water to follows osmotically onto the epithelial surface making it more watery
What is responsible for the spongy appearance of the lung tissue?
due to the abundance of alveoli sacs
The alveolar wall is made up of what kind of cells?
simple squamous cells
Smooth muscles fibers and elastic fibers are oriented how in the alveoli?
Smooth muscles fibers: concentrically in a spiral fashion
elastic fibers: longitudinally
What is the function of the elastic fibers?
help to expand the alveoli when we breathe in and contract when we breathe out
allow for recoiling of alveoli when we breathe out
What is the difference between pulmonary lobule and acinus?
The pulmonary lobule (sometimes called the secondary lobule) refers to an anatomic unit of lung parenchyma, 0.50 to 2.00 cm in diameter, bounded by interlobular septa. Lobules can be appreciated on cut section of lung tissue and on the pleural surface, and they usually comprise some ten to 30 acini.
The functional unit of the lung: a respiratory bronchiole and its alveolar ducts and alveolar sacs. (Note: The definition of “acinus” varies somewhat in the literature.)
What is the basic structural and functional unit of gas exchange?
alveoli
What is responsible for equalizing the pressure between adjacent alveoli?
Kohn cells
Where does blood supply for the alveoli come from?
pulmonary artery
What is the oxygenated status of the blood in the pulmonary artery?
low oxygenated blood
What is the oxygenated status of the blood in the pulmonary vein?
high oxygenated blood
Alveoli wall are made up of which two types of cells?
pneumocytes and septal cells (have lamellar bodies)
What is the function of the pulmonary surfactant secreted by type II alveolar cells (septal cells)?
- covers the surface of the alveolus
- when we breathe in air the alveoli expand and the surfactant reduces the surface tension making it easier for us to bring in the air and expand the alveoli
- when we expire it prevents the collapse of the alveolus; the surface tension is REDUCED allowing for contraction of the alveoli so they do not collapse
What are alveoli dust cells?
wandering macrophages that remove debris
What is the blood-air barrier?
alveolar-capillary barrier which consists of 4 layers to get from alveoli to blood
What is the function of the type I alveolar cells?
site of gas exchange
What are the 4 layers that gas has to travel to get from alveoli to blood?
- alveolar epithelial wall of type I cells
- alveolar epithelial basement membrane
- capillary basement membrane
- endothelial cell of capillary
What is the function of the type II alveolar cells?
-secrete pulmonary surfactant
-has lamellar bodies which store surfactant
-reduces surface tension
facilitates with expansion of alveoli
-prevents collapse of alveoli
Where are intra-alveolar macrophages easily found on histo slides?
in the open space of the alveolus
What are the effects of smoking in the lung?
-smoking paralyzes the cilia that help to clear mucous and inhibit macrophages
What is emphysema?
overproduction of macrophages
neutrophils destroy elastin through elastase resulting in emphysema (destruction of alveolar wall elastic fiber)
What is NRDS?
neonatal respiratory distress syndrome
insufficient production of surfactant resulting in increased alveolar surface tension; retain CO2 and not enough O2 into tissues; pulmonary hypoeffusion; damage of blood vessels (endothelial cell damage)
