Nose Flashcards
The conducting portion consists of
- Nasal cavities
- Nasopharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
- Terminal bronchioles
The respiratory portion consists of:
- Respiratory bronchioles
- Alveolar ducts
- Alveoli
The conducting portion serves two main functions:
- To provide a conduit through which air moves to and from the lungs
- To condition the inspired air.
Most of the conducting portion is lined with:
ciliated pseudostratified
columnar epithelium known as respiratory epithelium
Respiratory epithelium has at least five cell types:
- Ciliated columnar cells
- Goblet cells
- Brush cells
- Small granule cells
- Basal cells
Respiratory epithelium ciliated columnar cells are
the most abundant, each with about 300 cilia on its apical surface
Respiratory epithelium Goblet cells are
- Abundant in some areas of the respiratory epithelium
- Filled in their apical portions with granules of mucin glycoproteins.
Identify Goblet Cells
Respiratory epithelium Brush cells
- Brush cells express some signal transduction components like those of gustatory cells
- Have afferent nerve endings on their basal surfaces and are considered to be chemosensory receptors.
- Are a much more sparsely scattered and less easily found
- Columnar cell type, which has a small apical surface bearing a tuft of many short, blunt microvilli
Respiratory epithelium Small granule cells
- Are also difficult to distinguish in routine preparations
- Possess numerous dense core granules 100–300nm in diameter.
- Like brush cells, they represent about 3% of the total cells
- Are part of the diffuse neuroendocrine system
Respiratory epithelium Basal cells
- Small rounded cells on the basement membrane
- Not extending to the luminal surface
- Are stem cells that give rise to the other cell types.
Immotile cilia syndrome causes:
- Infertility in men
- Chronic respiratory tract infections in both sexes
Immotile cilia syndrome is caused by :
- Immobility of cilia and flagella induced
- In some cases by a deficiency of dynein, a protein normally present in the cilia.Dynein participates in the ciliary movement
The left and right nasal cavity each has two components:
- The external vestibule
- The internal nasal cavities (or fossae).
The vestibule is the most
anterior and dilated portion of each nasal cavity.
Within the vestibule, the epithelium
- Loses its keratinized nature
- Undergoes a transition into typical respiratory epithelium before entering the nasal fossae.
Skin of the nose enters the
nares (nostrils) partway up the vestibule
Embedded in the epithelial lining of the external vestibule are hairs called:
Vibrissae
Whiskers or vibrissae (singular: vibrissa) are
a type of mammalian hair that are typically characterised, anatomically, by their large size, large and well-innervated hair follicle and by having an identifiable representation in the somatosensory cortex of the brain
Where does epithelium loses its keratinized nature and undergoes a transition into typical respiratory epithelium
Within the vestibule,
The nasal cavities lie within the skull as
Two cavernous chambers
The nasal cavities are separated by
The osseous nasal septum.
Nasal Conchae.
Conchae are
Three bony shelflike projections extending from each lateral wall
Which conchae are covered with respiratory epithelium
- Middle
- ** Inferior**
Which conchae is covered with a specialized olfactory epithelium.
- Superior
(Labels are in foreign language)
Swell bodies are
Large venous plexuses within the lamina propria of the conchae
The narrow passages between the conchae
Improve the conditioning of the inspired air by
- Increasing the surface area of moist, warm respiratory epithelium
- Slowing and increasing turbulence in the airflow.
Every 20–30 minutes, the swell bodies on one side become
temporarily engorged with blood, resulting in
- distension of the conchal mucosa
- concomitant decrease in the flow of air.
During this time, most of the air is directed through the other nasal fossa, allowing the engorged respiratory mucosa to recover from dehydration.
Once the air reaches the nasal fossae…
particulate and gaseous impurities are trapped
in a layer of mucus.
The olfactory chemoreceptors are located in
The olfactory epithelium,
In humans the olfacotory epithelium is:
Area:
Thickness:
Area=10 cm2
Thickness=100 µm
The olfactory epithelium is made from
pseudostratified columnar epithelium composed of three cell types
Cell types of olfactory epithelium
- Basal cells
- Supporting cells
- Olfactory neurons
Identify Basal cells ,Supporting cells & Olfactory neurons
Identify Basal cells ,Supporting cells & Olfactory neurons
Basal cells are
- Small, spherical or cone-shaped
- Form a layer at the basal lamina.
- They are the stem cells for the other two types.
Supporting cells are
- Columnar
- Have Broad cylindrical apexes
- Narrow bases.
- On their free surface are microvilli submerged in a fluid layer.
Supporting cells are bound
to the adjacent olfactory cells by:
Well-developed junctional complexes
Supporting cells express abundant ion
channels whose function appears to be required to
maintain a
microenvironment conducive to olfactory function and survival.
Olfactory neurons are
Bipolar neurons
Olfactory neurons are
distinguished from supporting cells by the
position of their nuclei, which lie between those of the supporting
cells and the basal cells.
The dendrite end of each olfactory neuron is
the apical (luminal) pole of the cell
The apical (luminal) pole of the cell has
a knoblike swelling
with about a dozen basal bodies.
From the basal bodies emerge
long nonmotile cilia with defective axonemes but a considerable surface area for membrane chemoreceptors.
These chemoreceptors receptors respond to
odoriferous substances by
- Generating an action potential along the (basal) axons of these neurons
- The axons leave the epithelium and unite in the lamina propria as very small nerves
- which then pass through foramina in the cribriform plate of the ethmoid bone to the brain.
In the brain Olfactory neurons axons merge to form
Cranial nerve I (The olfactory nerve)
They eventually synapse with other neurons in the olfactory bulb.
The lamina propria of the olfactory epithelium possesses
large serous glands called:
The Glands of Bowman
The Glands of Bowman
- produce a flow of fluid surrounding the olfactory cilia
- Facilitate the access of new odoriferous substances.
The olfactory neurons are some of the only neurons
to be replaced regularly and constantly due to regenerative activity of the epithelial stem cells from which they arise.
Lloss of the sense of smell due
to toxic fumes or physical injury to the epithelium is
usually
Temporary.
(due to regenerative
activity of the epithelial stem cells from which olfactory neurons arise)
Permanent loss of olfaction occurs if
there is damage to the** ethmoid bone** at the base of the skull that_ shears the olfactory axons_ and blocks axonal regeneration through the cribriform plate.
The paranasal sinuses are:
Bilateral cavities in the
- Frontal
- Maxillary
- Ethmoid
- Sphenoid bones
of the skull
The paranasal sinuses communicate with
the nasal cavities through small openings
Mucus produced in the sinuses is moved into the nasal passages by
the activity of the ciliated epithelial cells.
Sinusitis is an
inflammatory process of the sinuses that
may persist for long periods of time, mainly because of
obstruction of drainage orifices.
Chronic sinusitis and bronchitis are components of immotile cilia syndrome, which is characterized by defective ciliary action.
