Histo Block I: resp sys- gen characteristic, olfactory/respiratory epithelium Flashcards
What are the primary functions of the respiratory system?
1.Air conduction
2.Air Filtration
3.Gas exchange (respiration)
What are the secondary functions of the respiratory system?
*Conditioning the air: Warming air, moistening and removal of particulate materials
*Defense (lymphocytes)
*Role in speech production
What are the 2 portions of the respiratory system?
conducting portion and a respiratory portion
What does the conducting portion of the respiratory system consists of ?
- Passages outside the lung
-Nasal cavities and the oral cavity
-Nasopharynx and oropharynx
-Larynx
-Trachea
-Primary bronchi (pair) - Inside the lung
-The bronchi undergoes extensive branching to form the bronchial tree
In what portion does the gas exchange occur?
respiratory portion
What are the components of the respiratory portion?
1.Respiratory bronchioles
2.Alveolar ducts
3.Alveolar sacs
4.Alveoli
Which are the structural basis for gas exchange?
Blood vessels enter the lung with bronchi. The arteries branch to form capillaries that come into very close contact with the alveoli.
What are the nasal cavities?
Pair chambers separated by a bony and cartilaginous septum
which are the 3 segments of the nasal cavity?
–Vestibule
–Respiratory segment
–Olfactory segment
what is the classification of the epithelium of the vestibule?
The vestibule is lined with epit. strat. squamous a continuation to the skin.
Whta type of secretions are in the vestibule and what are vibrissae?
Mucous and serous secretions.
Short stiff hairs called vibrissae entrap large particulate matter.
What is the epithelium of the respiratory segments of nasal cavity?
Lined with pseudostratified columnar ciliated epithelium with goblet cells. The lamina propria is attached to the bone by the periosteum
WHat are some functions of the respiratory segment of the nasal cavity and wha cell are present?
*Filter, warm and humidify air in normal respiration.
*Production of mucous for protection.
*Respiratory mucosa of the nasal cavity contains cells involved in mucosal immunity. The majority are gamma/delta T lymphocytes.
*Many other cells participating in defense are present in the lamina propria: T lymphocytes, B lymphocytes, neutrophils, macrophages, and mast cells.
WHta components does the lamina PROPIA have?
In the lamina propria abundance of capillaries, venules and small veins in the lamina propria. When have a cold or allergy, vessels leak and tissue swells.
how is the basement membrane and lamina propia in the respiratory epithelium?
A defined basement membrane, and lamina propria very cellular, with many lymphocytes
What is the lymphatic tissue in the respiratory epithelium?
Lymphatic tissue, in both diffuse and nodules is present. This lymphatic tissue is functionally similar to the bronchus-associated lymphatic tissue (BALT).
Identify
Photomicrograph of respiratory epithelium. Showing ciliated columnar cells, mucus-secreting goblet cells and basal cells.
What are the 5 types of cells present in the respiratory epithelium?
- Ciliated cells
- Goblet cells
- Brush cells
- Small granule cells (Kulchitsky cells)
- Basal cells
Which cells of the respiratory epithelium are the most identified, prominent and what is their function?
ciliated cells; tall columnar cells with
cilia that project into the mucus covering
the surface of the epithelium. They are the
most abundant cells (up to 70%).
function of goblet cells
synthesize and secrete mucus (5% to 15% present); increase if epithelium is exposed to irritating substances
function of brush cells
cells with short, blunt
microvilli. Are chemosensory receptor cells
connected to sensory nerve fibers.
function of small granule cells?
contain secretory granules; they are endocrine cells of the diffuse neuroendocrine system (DNES); their function is not clear
function of basal cells
are stem cells, on top of the
basement membrane and have no contact
with the epithelial surface; give origin to other cells in the epithelium
identify
Respiratory epithelium, pseudostratified ciliated epithelium with goblet cells. (H&E) lamina propria with many blood vessel
identify
This electron micrograph shows the three main cell
types of this respiratory epithelium:
1) ciliated epithelial cells extending to the surface, where they possess cilia
2) goblet cells with mucinogen granules
3) basal cells, which are confined to the basal portion of the epithelial layer near the connective tissue.
identify
Olfactory Epithelium and Respiratory Epithelium
The olfactory mucosa (OM), adjacent ethmoid bone (EB) is directly attached to the bone tissue; no
submucosa is present. In this specimen, however, the mucosa is separated from the bone tissue because of
shrinkage, a frequently encountered artifact. The olfactory epithelium (OEp) is pseudostratified, like
respiratory epithelium; however, it is typically thicker. Note the respiratory epithelium (REp) included in the
lower right of the micrograph. The feature that is most useful in identifying olfactory mucosa is the presence of numerous large, unmyelinated nerves (N) and extensive olfactory (Bowman’s) glands (BG) in the
connective tissue of the mucosa. Occasional blood vessels (i.e., arteries [A] and veins
The olfactory epithelium classification is?
The olfactory epithelium is pseudostratified columnar,
without goblet cells
where is the olfactory region of the nasal cavity located?
It is located on part of the dome in each nasal cavity.
how much space does the olfactory mucosa take?
It is lined with specialized olfactory mucosa. In humans the olfactory mucosa is aprox.10 square centimeters.
WHat does the lamina propia of the olfactory mucosa contain?
contains blood and lymphatic vessels, unmyelinated olfactory nerves, myelinated olfactory nerves and
olfactory glands
identify
The olfactory epithelium exhibits nuclei through much of its thickness. The underlying connective tissue is largely occupied by numerous olfactory (Bowman’s) glands, olfactory nerves, and blood vessels
What type of cells can we find in the nasal mucosa in the olfactory epithelium?
- olfactory receptor cells
- supporting or sustentacular cells
- basal cells
- brush cells
function of olfactory receptor cells?
are bipolar neurons. Extend along the whole
thickness of the epithelium and enter CNS (Cranial N. I)
function of supporting or sustentacular cells
provide mechanical and metabolic
support to the olfactory receptor cells
function of basal cells
are stem cells for both receptors and supporting cells
function of brush cells
are the same cell type as in respiratory epithelium
cells with short, blunt microvilli. Are chemosensory receptor cells connected to sensory nerve fibers
identify
The 3 principal cell types of the olfactory
epithelium can be distinguished on the basis of
nuclear location and appearance
1) The nuclei of the supporting cells (SC) are
relatively dense and are located closest to the
epithelial surface.
2) The cell bodies of the olfactory receptor cells
(OC) lie at different levels within the thickness of
the epithelium.
3)The basal cells (BC), are irregularly spaced and
lie in proximity to the basement membrane.
The lamina propria contains blood vessels,
capillaries (C), veins (V), lymphatics, olfactory
nerves (N), and olfactory (Bowman’s) glands
(BG). They exhibit a very small lumen (arrows).
Very thin axonal processes (AP) of the olfactory
cells are evident within the lamina propria prior
to being ensheathed by olfactory ensheathing
cells (OECs) NOT (ScC).
What is the life span of olfactory cells?
1 month and injured they regenerate or are replaced
what is anosmia?
loss of the sense of smell and it can be caused by traumatic head injury leading to permanently damage of these axons and covid
what is the olfactory vesiclee?
The olfactory receptor cell has a single
dendrite that forms the olfactory vesicle
describe olfactory cilia
A number of long thin cilia (10 to 23)
olfactory cilia. Are long and non-motile
cilia lying parallel to surface.
what does the base of the olfactory cell give rise to?
The base of the cell gives rise to an
unmyelinated axonal process that leave
the epithelia. Unmyelinated axons are
grouped into bundles that pass the
cribriform plate. They form the olfactory
nerve (Cranial nerve I)
where does the olfactory transduction pathway occurs?
within the cilia of the olfactory receptor cells
explain the olfactory transduction pathway
The chemical signals (odorants) selectively bind to odorant-binding proteins (OBP). Are water soluble
proteins synthesized by the supporting cells.
The OBP act as carriers to take them to the olfactory receptors (ORs) located in the plasma membrane of the cilia. More than 350 types exist in humans.
Olfactory receptors are specific for the olfactory receptors cells and are Gprotein- coupled receptors
Stimulated by odorant molecules, olfactory receptors activate enzyme adenylyl cyclase and initiate the cAMP cascade of events leading to the opening
of specific channels. Influx of Na+ and Ca2+ is responsible for cell depolarization.
explain the pathway of the olfactory nervous system
Generated action potential travels on axons of olfactory receptor cells from the nasal cavity, passing through the ethmoid bone and surrounding brain coverings to the olfactory bulb of the brain
what is the function of the supporting cells?
provide mechanical and metabolic
support for the olfactory receptor cells. function compareble to neuroglial cells of CNS
which cells are the most numerous in the olfactory epithelium?
SUPPORTING CELLS
How si the nuclei of supporting cells?
The nuclei are closer to the apical region
which what cells do supporting cells form adherent junctions
They form only adherent junctions with the olfactory
receptor cells
What are olfactory glans and where are they located?
are a characteristic of the olfactory mucosa (Bowman’s glands)
They are branched tubuloalveolar serous glands present in lamina propia of olfactory mucosa
what type of secretion do olfactory glands have and their function
The serous secretions of the glands serve as solvent for odoriferous substances. Eliminates and move residuals in cilia, to clean. Constant flow from the gland gets rid of remnants allowing new odors to be detected
explain the lipofuscin pigment in olfactory glands
*Lipofuscin pigment in the
glands adds to the yellow
appearance of the mucosa
identify
olfactory glands
what is the general pattern of the conducting portion of the respiratory system?
- mucosa
- submucosa
- cartilaginous layer
4 adventitia
What are the characteristics of the mucosa of the conducting portion of the respiratory system?
- Respiratory epithelium
- Thick basement membrane
- Lamina propria (loose cellular CT with blood vessels and lymphoid elements)
- Bronchial Associate Lymphatic Tissue (BALT)
- The boundary between mucosa and submucosa is defined by an elastic membrane.
What are the characteristics of the submucosa of the conducting portion of the respiratory system?
Connective tissue (dense - loose)
Mixed glands (mucous and seromucous)
Smooth muscle
Venous plexus / lymphoid tissue
What are the characteristics of the cartilaginous layer of the conducting portion of the respiratory system?
*Hyaline cartilage (not present in all structures)
What are the characteristics of the adventitia of the conducting portion of the respiratory system?
Loose elastic, reticular or collagenous CT
identify
General Pattern of the Conducting Portion of the
Respiratory system
WHat are the regions of the conducting portion?
nasal region
paranasal sinuses
pharynx
eustachian tube
pharyngeal tonsil
the nasal region is coverd by?
by olfactory and respiratory epithelium
what are paranasal sinuses?
are air filled spaces in the bones of the wall of
the nasal cavities. The mucosal surface of the sinuses is covered by thin pseudostratified ciliated epithelium with goblet cell. Paranasal sinuses are the main sites for nitric oxide (NO) production in the airways. Nitric oxide may play an important role in the nasal defense
mechanisms against invading microorganisms and facilitates gas exchange in the lungs.
what is the pharynx?
Connects the nasal and oral cavities to the larynx and esophagus.
Divided in nasopharynx and oropharynx.
what does the Eustachian tube do?
connects the middle ear to the nasopharynx
what is the pharyngeal tonsil composed of?
Present aggregates of lymphatic nodules in the junction between superior and posterior walls
