Respiratory System Flashcards
The respiratory system is divided into what two portions and their major functions
Conducting portion: cleanse and humidify the air
- nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchiole, terminal bronchiole
Respiratory portions: gas exchange
- respiratory bronchiole, alveolar duct, alveoli
Respiratory epithelium makes up most of the conducting portion -
What kind of epithelium is it?
Ciliated pseudostratified columnar epithelium
At least 5 types of cells that all touch the basement membrane:
Ciliated columnar, Goblet cells, Brush cells, Small granule cells, Basal cells
Where would you find things like glands and cartilage here?
Lamina propria
What is the purpose of the cilia?
Help move mucus and debris out of the respiratory tract
What are the black arrows pointing at here?
What is its function?
Goblet cells produce mucin (becomes mucus when mixed with water to trap particulates)
- NO cilia
- Not as abundant as the ciliated columnar cells, but can be very abundant in some areas
- Bulging apical surface filled with granules of mucin glycoproteins –> light apperance
What cell type in respiratory epithelium is
- columnar
- short microvilli
- chemosensory receptors resembling gustatory cells
- afferent nerve endings on basal surface
Brush cells gives you gustatory sense and afferent nerve endings
(Don’t have to identify them bc they only make up 3%)
What cell type is
- part of the diffuse neuroendocrine system
- contains many dense core granules
Small granule cells
(don’t have to identify, either; just as rare as brush cells)
Basal cells identification & function
-
Small rounded cells on basement membrane
- DO NOT extend into the lumen
- Nuclei are basally located
- Stem cell that gives rise to other cell types
Where is olfactory epithelium found?
What is its function?
Within the epithlium overlying the superior nasal conchae
Gives you sense of smell
What kind of cells make up olfactory epithelium?
What is in its lamina propria?
- Supporting cells - columnar cells w/ microvilli
- Olfactory cells - bipolar neurons
- Basal cells - stem cells for the other cells
In the lamina propria, there are bowman’s glands and nerve tissue bundles
Why is there NO MUCUS overlying the ciliated portion of olfactory epithelium?
No goblet cells!
What cell type is the black arrows pointing at? What is their function?
Supporting cells forms a line of nuclei near the luminal surface
Have ion channels for olfactory function and olfactory neuron survival
What cell type is this?
Olfactory cells (bipolar neurons)
Nuclei are right below the supporting cells
What cell type is this?
Basal cells
adjacent to teh basement membrane of the olfactory epithelium
The lamina propria of olfactory epithelium contains what 2 significant structures?
What is this a scanning EM of?
The apical/dendritic end of an olfactory neuron with ~a dozen basal bodies from which long cilia project into the overlying aqueous layer
Glands surrounding the neuron constantly bathe the cilia
Olfactory neuron functioning steps
- Chemoreceptors on cilia axonemes respond to odoriferous substances
- Action potential goes down an axon
- Axon leaves the epithelium and unites in the lamina propria as very small nerves -> pass through foramina in the cribriform plate to the brain, where they form the olfactory nerve (CN1)
- Synapse with neurons in the olfactory bulb of the brain
- Regenerative neurons
function of bowman’s gland
Produces a constant flow of fluid surrounding olfactory cilia -> helps new odoriferous substances to access the cilia chemoreceptors of olfactory neurons
What is this?
horizontal cut of the nasal cavity
What is this?
Frontal/coronal section of the nasal cavity
How do nasal conchae promote the sense of smell?
They incrase turbulence wihtin teh nasal cavity, thus increasing contact between the inspired air and the mucosa
The nasal cavity is lined mostly with ___ epithelium, but also contains…
Respiratory epithelium, but also contains
- Swell bodies: thin-walled vessels just deep to the epithelium; warms air
- Olfactory epithelium on the most superior part
What is this?
Respiratory epithelium of the nasal cavity
- goblet cells
- cilia
- glands
What is this?
Olfacatory epithelium of nasal cavity
- lots of dark nuclei with no goblet cells
- bowman’s glands*
- axon bundles
(thsi cilia is nonmotile)
How do you identify nasopharynx?
- Respiratory epithelium only
- Tonsil = big aggregations of lymphocytes; in the lamina propria
What is this?
Nasopharynx
it has lymphatic patches (big aggregations of lymphocytes) in the lamina propria
What features would we see on a larynx?
- Epithelial transition on vocal and vestibular folds
- Skeletal muscle
- Cartilage & bone
What is this?
Larynx (midsaggital)
What are the black arrows pointing to in this cross section of the larynx?
Cartilages of the larynx
What is the black arrow pointing to in this cross section of the larynx?
Thyroid gland
The larynx has what two types of epithelium? Where do you see the transition?
Respiratory (ciliated pseudostratified columnar) epithelium transitions to stratified squamous epithelium over the epiglottis, vocal folds, and oropharynx (protects against the abrasion to air)
You’ll see the goblet cells disappear.
What is this?
Trachea : C-shaped cartilage ring
Trachea microanatomy
- ___ epithelium
- ___ in the lamina propria
- C-shaped rings of ____ cartilage
- ___ surrounds the whole organ
- ___ is attached to the perichondrium
Respiratory epithelium
A LOT of seromucous glands
C-shaped hyaline cartilage
Adventitia around the whole organ
Trahcealis muscle fibroelastic tissue attached to perichondrium
The black arrow here points to
Trachealis muscle
Bronchi
Identification by cartilage, epithelium, lamina propria, glands, etc
- Irregular, smaller plates of cartilage
- Respiratory epithelium
-
Thin, elastic lamina propria completely encircled with smooth muscle (spiral organization)
- Seromucinous glands in the submucosa (but not as much as trachea)
- Submucosa merges w/ adventitia and lung parenchyma
- Small aggregates of lymphoid tissue
How do you know this isn’t a primary bronchi? (The big one)
It’s in the lung, so it can’t be primary
The other bronchi (purple= cartilage, unlike the vessel above it) may be even tertiary
What is this?
Bronchi because very thin respiratory epithelium
- Right below is thin smooth muscle that will constrict the airway
- Layer of very dark purple cartilage
- Alveolar space right below it abutting the bronchus
What organ has this epithelium?
Bronchus
has cilia, but nowhere near as much stratification
You can see you’re in the lung and you can see cartilage
Bronchiole identification
NO cartilage
NO glands in the submucosa
The epithelia gets even thinner than the bronchi and transitions from pseudostratified colum > simple colum > simple cuboidal epithelial transition
The terminal bronchioles (left) are the last conducting airway.
How do you identify them?
Goblet cells replaced with club cells (other columnar-shaped cells) and exocrine bronchiolar cells
Club/Clara cells’ identification
Dome-shaped
Non-ciliated
Has lots of secretory granules containing surfactant components (lipoproteins & mucus)
What is the function of these cells?
Club cells
- Divide and replace damaged type I & type II pneumocytes
- Secretes surfactant components (lipoproteins & mucins)
- Enzymatic components which can detoxify noxious substances that have been inhaled
- Releases cytokines to stimulate local immune reseponse in the lung
The lamina propria of what organ is composed largely of smooth muscle & elastic fiber?
Bronchioles
The muscles of bronchioles are under control of
Muscle controlled by vagus & sympathetic nerves
(Sympathetics causes relaxation of these muscles to increase airway)
Here, you see a terminal bronchiole (left) turn into a ____ (right).
How can you identify this transition?
Respiratory bronchiole: the first part of the respiratory portion
- Shorter & thinner walled
- Still see scattered epithelial cells (so you know it’s not an alveolar duct
- Small # of single alveoli in the walls
- Transition from ciliated cuboidal w/club cells –> exclusively club cells at terminal portions
What is this transition? how do you know?
Terminal bronchiole (left, darker) -> Respiratory bronchioles
Smaller # of single alveoli in the wall
Alveolar air spaces have 3 components:
Surface epithelium
Fibroelastic intersititum - the thin supporting connective tissue at the basement membrane
Pumonary capillaries
This is
Alveoli
Saclike evaginations of the respiratory bronchioles, alveolar ducts, and alveolar sacs
Alveolar epithelium
-
Continuous lining of the alveoli
- Mostly type I pneumocytes
- type II pneumocytes (66% of the cells, but only 5% of surface area)
What kind of cell is the cursor on?
What is its purpose?
Type I pneumocyte (stretched and flat, won’t always see the nucleus)
- Thin barrier for gas exchange
What is the cursor on? What cell is this?
Lamellar body: contains newly synthesized surfactant
This is a type 2 pneumocyte: rounded cells between two alveoli that produces pulmonary surfactant
What does surfactant contain? What is its purpose?
- Surfactant contains:
- Phospholipids, especially DPPC
- Surfactant proteins (SPA-D)
- Lowers surface tension
What type of cell is this?
how can you tell?
type 2 pneumocyte
White space around the nucleus i think
What is this?
- Supporting connective tissue made of ___ and ___ fibers
- Important for ____
Interalveolar septum
- Elastic and collagen (reticular) fibers
- Important for elastic recoil of alveoli; also has immune cells
Where do you find immune cells?
What type?
Within the interstitium or within the alveoli.
Most are macrophages (dust cells), picking up debris
Explain gas exchange in the alveolar space
Oxygen has to penetrate the epithelial cells lining the alveolar space (type 1 pneumocyte) > thru interstitium > thru plasma membrane > red blood cell
Carbon dioxide just goes in the opposite direction
What two cells share a basal lamina in the barrier for gas exchange?
Pneumocyte type 1 shares a basal lamina with the endothelial cell of the capillary
What is the serous membrane/serosa?
Mesothelial layer on the outside of the lung (visceral pleura) + the underlying connective tissue
This is a picture of lung parenchyma. What is the purple outline the black cursor pointed at?
What kind of cells are there?
Visceral pleura = simple squamous mesothelium
How to differentiate between respiratory and olfactory epithelium?
The olfactory epithelium does not contain goblet cells and is thicker than the respiratory epithelium (black arrows).
Lamina propria of the olfactory mucosa is quite thick containing serous glands (G, white arrows) and nerve bundles, filia olfactoria (F).
What kind of epithelium will you see on the epiglottis, vocal folds, and oropharynx?
Stratified squamous (nonkeratinized)
