Histo block I: resp sys- larynx, trachea, bronchi Flashcards
function of larynx
Function as a conduit for air conduction and sound production. The vocal folds control de flow of air through the larynx and vibrate to produce sound.
What is the larynx and by what is it formed?
*Passageway for air between the oropharynx and trachea
*Form by irregular shaped plates of hyaline and elastic cartilage
What are the vocal folds?
(vocal cords) are two folds of mucosa that project into the lumen of the larynx. A supporting ligament and skeletal muscle “the vocalis muscle” is contained
within each fold.
what is the ventricular folds?
located above the vocal folds are the “false vocal cords”. Do not have muscle. Abundant mucoserous
glands
identify
The right half of the larynx, the ventricle (V), the
ventricular folds (false vocal cords) (VF) and vocal
folds (VoF). The vestibule (Ve) and the infraglottic
cavity (IC). The vocalis muscle (VM) and mucous and
seromucous glands (GI). The laryngeal cartilages
(LC)
what type of epithelium is present in ventricular folds?
pseudostratified columna ciliated epithelium with goblet cells
what type of epithelium is present in vocal folds?
stratified squamous epithelium non-keratinized
whar are the 3 types of epithelia in the respiratory mucosa?
Respiratory (predominant)
Olfactory
Stratified squamous non-keratinized epithelium
what is metaplasia or squamous metaplasia?
change ciliated pseudostratified columnar epithelium to stratified squamous epithelium. Basal cell proliferation gives rise to the new cell type.
Squamous metaplasia is normal on the vocal folds, and in certain other regions.
In chronic bronchitis and bronchiectasis, the respiratory epithelium changes in certain regions to a stratified squamous. The altered epithelium is more resistant but less effective functionally.
If the factors (i.e., tobacco smoking) that predispose to squamous metaplasia are not eliminated, the metaplastic epithelium may undergo malignant transformation.
Trachea divides into?
Trachea→ 1ry bronchi→ 2ry bronchi → bronchial tree→ terminal bronchiole
describe the trachea
Is an air conducting flexible tube of about 10 cm long. The trachea extends from the larynx to the middle of the thorax and then divides in two to form the main (primary) bronchi.
describe the mucosa of the trachea?
Composed of ciliated pseudostratified epithelium and a lamina propria, rich in elastic fibers and goblet cells
describe the submucosa of the trachea?
Moderately dense connective tissue (CT) and glands
describe the cartilaginous layer of the trachea?
composed of C-shaped hyaline cartilage. Fibroelastic tissue and smooth muscle connects the ends of the C-cartilage plates
describe the adventitia layer of the trachea?
Composed of CT that binds the trachea to adjacent structures
identify
Photomicrograph of trachea (H&E). Showing mucosal layer, submucosal layer, hyaline cartilage and adventitia
identifty
Electron micrograph of human tracheal epithelium
identify
goblet cells in human tracheal; epithelium
which cells are present in the tracheal epithelium?
- ciliated cells
- mucous cells (goblet)
- brush cells
- small granule cells (kulchitsky cells)
- basal cells
describe ciliated cells in tracheal epithelium
the most numerous. Each cell has approximately 250 cilia. The cilia provide a coordinated sweeping motion of the mucous toward the pharynx.
describe mucous cells (goblet) in tracheal epithelium
They have accumulated mucinogen granules in their cytoplasm. The number of mucous cells increases during chronic irritation.
describe brush cells in tracheal epithelium
are regarded as general sensory and chemoreceptors cells. Afferent nerve endings.
describe small granule cells (kulchitsky cells) in tracheal epithelium
are enteroendocrine cells. With immunolabelling and EM, show granules containingcatecholamines, serotonin,calcitonin, andgastrin-releasing peptide (bombesin).
Not clear function, maybe regulating ating the airway or vascular caliber.
describe basal cells in tracheal epithelium
cellsrepresent a stem cell population.
how is the basement membrane of the trachea?
A thick “basement membrane” is characteristic. In smokers and individuals with asthma, this layer may be considerably thicker, a response to mucosal irritation.
how si the lymphatic tissue in the trachea?
Lymphatic tissue in both diffuse and nodular form can be present.The boundary between mucosa and submucosa is defined by an elastic membrane.
how si the submucosa in the trachea?
The submucosa connective tissue is relatively dense CT and contains larger vessels and lymphatics. Submucosal glands composed of mucous-secreting acini with serous demilunes. Abundant in the posterior cartilage free area
identify
trachea
what separates submucosa from adventitia?
The tracheal cartilage and trachealis muscle; in humans 16-20 C-shape cartilages are present
what happens to the hyaline cartilage in the trachea with age?
With age the hyaline cartilage may be partially replaced by bone, causing loss of flexibility
what is th efucntion of the adventtiia in the trachea?
Outer layer of connective tissue, binds the trachea to other structures and provides blood vessels, nerves and lymphatics.
identify
Photomicrograph of a section of the trachea and esophagus
Primary bronchi come from?
from bifurcation of trachea and are extrapulmonary
what changes in the bronchi when it enters the lung?
the walls; The cartilage rings are replaced by plates of irregular shapes
which are the bronchi that are intrapulmonary?
Intrapulmonary bronchi are secondary (lobar bronchi) and Tertiary (segmental bronchi).
bronchi can be identified by?
cartilage plate and circular layer of muscle
what is the mucosa in the bronchi?
Respiratory epithelium pseudostratified ciliated with goblet cells
what is the muscularis in the bronchi?
a continuous layer of smooth muscle in the larger bronchi. More attenuated and loosely organized in the smaller bronchi. Contraction regulate diameter.
what is the submucosal in the bronchi?
loose connective tissue and glands. Bronchus-associated lymphatic tissue (BALT) in lamina propria
the cartilage layer of discontinous plates of hyaline cartilage in the bronchi becomes smaller or larger as bronchial diameter decreases?
become smaller as bronchial diameter decreases
how is the adventitia in the bronchi?
moderately dense CT continuous with lung parenchyma
identify
wall of bronchi
identify
Intrapulmonary Bronchus
what are bronchioles?
Bronchioles are air-conducting ducts that measure 1 mm or less in diameter. The larger bronchioles represent branches of the segmental bronchi.
what structures are not present in the bronchioles?
Cartilage plates and glands
epithelium in bronchioles transforms into what?
Epithelium gradually transforms from pseudostratified into a simple ciliated columnar epithelium as the duct narrows and cuboidal too in smaller structures
The terminal bronchioles finally give rise to
respiratory bronchioles
which cells are present in the bronchioles?
- ciliated cells
- goblet cells
- club cells (clara cells)
- brush and small granule cells
functions of ciliated cells in bronchioles
important for the moving mucous and debris upwards along the bronchial.
Kartagener’s syndrome when dyenin arms are not present in cilia, mucus accumulates and you get chronic respiratory infections
are goblet cells present in bronchioles?
are still present in the largest bronchioles but are NOT present in the terminal bronchioles
characteristics of club cells
have a characteristic rounded or dome-shaped apical surface projection. They display characteristics of protein-secreting cells
function of club cells
increase in number as the ciliated cells decrease along the length of the bronchiole
identify
bronchiole
what do club cells secrete?
secrete a surfaceactive agent, a lipoprotein that prevents luminal adhesion should the wall of the
airway collapse on itself during expiration.
16 kDa protein known as Club cell secretory protein (CC16), which is abundant in the airway secretion
why is CC16 important?
In chronic obstructive pulmonary
disease (COPD) and asthma CC16 levels
decrease in bronchoalveolar lavage fluid
and increase in blood serum, due to
leakage across the blood air barrier.
* CC16 in an indicator of lung damage.
what happens if xenobiotic coumpunds are inhaled?
Detoxification by enzymes of SER. Club
(Clara) cells express high levels of
cytochrome P450 monooxygenases.
identify
club cells (clara)
identify
club cells clara
which bronchi is the last of the conducting poertion?
terminal bronchioles
what structure leas to respiratory bronchioles?
terminal bronchioles (simple cuboidal epithelium)
which brinchioles are the first of the respiratory portion?
respiratory bronchioles
what structure is interspersed int he wall of respiratory bronchioles?
alveoli
what are the alveolar ducts?
linear arrangement of alveoli
what are the alveolar sacs?
cluster of alveoli at end of alveolar ducts
what is the epithelium of alveoli and their function?
are made of simple squamous epithelium. Are the
sites of gas exchange (blood-air barrier)
identify
a terminal bronchiole (TB) is shown
longitudinally sectioned as it branches into two respiratory
bronchioles (RB). Respiratory bronchioles give rise to alveolar
ducts (AD), which are elongate airways. Alveolar sacs (AS) are
spaces at the termination of the alveolar ducts that, likewise,
are surrounded by alveoli
First part of respiratory system to participate in gas exchange
respiratory bronchioles
what is the epithelium of respiratory bronchioles?
epithelium is cuboidal (mostly Club (Clara)
cells (CC) and few ciliated cells).
IDENTIFY
Section of the lung from a patient with asthma shows a bronchiole in the center with surrounding
alveoli. The bronchiolar wall is thick, inflamed, and has enlarged blood vessels. BRONCHIAL ASTHMA
IDENTIFY
This high-magnification photomicrograph shows the structure of a bronchiolar pseudostratified
columnar epithelium containing a large number of goblet cells. The mucus in the lumen is a product
of the goblet cells. Note the presence of a large number of eosinophils (cells with red cytoplasm),
lymphocytes, and other connective tissue cells that infiltrated the lamina propria and submucosa of
the bronchiole. The basement membrane is thick and well defined. The smooth muscle layer is also
thick and the underlying adventitia contains enlarged blood vessels
