Histology π¬ Flashcards
What is the respiratory system classified into?
There are 2 ways to classify respiratory system:
- Structural classification:
i. Upper respiratory tract
ii. Lower respiratory tract - Functional classification:
i. Conducting portion: For conduction and filtration of air.
ii. Respiratory portion: For Gas exchange (respiration).
What does the conducting portion of the respiratory system include?
1.Nasal cavities & sinuses.
2- Nasopharynx.
3- Larynx.
4- Trachea.
5- Bronchi.
6- Bronchioles.
7- Terminal bronchioles.
What does respiratory portion of the respiratory system include?
- Respiratory bronchioles.
- Alveolar ducts.
- Alveolar sacs.
- Alveoli.
What is the nose divided into?
1) The vestibule
2) 2 Nasal fossae separated into:
a. Respiratoryregion.
b. Olfactory region.
What is the vestibule and what is it lined by?
β’ It is the external dilated part.
β’ Lined by thin skin with thick hairs called vibrissae for filtration of air.
What is the respiratory region of the nasal fossa and what is it lined by?
β’ The constitutes the inferior 2/3 of the nasal fossae.
β’ It is lined by respiratory mucosa formed of: Epithelium and corium
What is a histological structure of the mucosa of the Respiratory region of the nasal Fossa?
Epithelium: Pseudostratified columnar ciliated epithelium with goblet cells.
Corium:
β’ Dense fibroelastic CT.
β’ Swell bodies: which are large venous plexuses
What is olfactory region of the nasal fossa?
β’ The constitutes the upper 1/3 of the nasal fossae (roof).
β’ It is lined by olfactory mucosa formed of : Epithelium and corium
What is the hosiological structure of the olfactory mucosa of the olfactory region of the nasal Fossa?
Epithelium: Neuroepithelium formed of 3 types of cells:
- Sustentacular (supporting) cells: Columnar cells
with oval nuclei and cytoplasm contains yellow pigments. Has apical microvilli. - Olfactory (sensory)cells: Bipolar nerve cells with oval nuclei. Their dendrites have long non motile cilia. Their axons collect to form the olfactory nerve. 3. Basal Cells: Small pyramidal cells responsible for regeneration.
Corium:
β’ Contains Bowmanβs glands.
β’ These glands secrete serous fluid which acts as a solvent for the odorous gases.
What is the definition of paranasal sinuses?
Bilateral cavities in the ethmoid, frontal, maxillary, sphenoid bones of skull. Lined by thin respiratory epithelium with fewer goblet cells.
What is the definition of the nasopharynx and what lines it?
β’ It is the first part of the pharynx.
β’ Lined by respiratory epithelium
What is the histological structure of the nasopharynx?
Epithelium:
pseudo-stratified columnar ciliated epithelium with goblet cells.
Corium: contains Pharyngeal tonsils (adenoids).
What is the definition of Larynx?
The Larynx is a rigid short tube between the pharynx and trachea .
What is the histological structure of the Larynx?
Epithelium: Pseudo-stratified columnar ciliated with goblet Cells except vocal cords, anterior (lingual) surface of epiglottis.
Corium (Lamina propria): contains laryngeal cartilages (reinforces its wall).
from where does the epiglottis project and what is its function?
β’ It projects from the upper rim of larynx.
β’ It acts as a valve to prevent swallowed food or fluid from entering the trachea.
What is the histological structure of the epiglottis ?
Epithelium :
β’ The lingual surface: stratified squamous non keratinized epithelium.
β’ The laryngeal surface: pseudo-stratified columnar ciliated epithelium.
Lamina propria: contains glands.
What are the vocal cords?
They are 2 pairs of mucosal folds that extend into the lumen.
A. False vocal cords:
β’ The upper pair.
B. True vocal cords:
β’ The lower pair.
What is the function of the vocal cords?
The upper pair: β’ Protect larynx from foreign bodies.
The lower pair: β’ For phonation.
What lines the vocal cords?
The upper pair: β’ Lined by pseudostratified columnar ciliated epithelium.
The lower pair: β’ Lined by stratified squamous non keratinized epithelium.
What is the structure of the trachea?
formed of
1. Mucosa.
2. Submucosa.
3. Fibro-Cartilaginous coat.
4. Adventitia.
What is the structure of the mucosa of the trachea?
Epithelium: (7 types of cells)
1) Ciliated cells: columnar ciliated, cilia beat towards larynx.
2) Goblet cells: have expanded apical part distended with mucin granules.
3) Basal cells: stem cells
4) Brush cells: Columnar with few microvilli. Depleted goblet cells or intermediate between basal and goblet cells.
5) Kulchitsky cells: Have neuroendocrine function. Secretes serotonin & calcitonin.
6) Serous cells: Apical electron dense granules. Produce serous secretion.
7) Migratory cells.
Corium (Lamina Propria):
βͺ Loose C.T rich in elastic fibers, blood vessels
βͺ Elastic fibers condense to form elastic membrane between corium & submucosa.
What is the structure of submucosa of the trachea?
βͺ Loose CT contains tracheal glands which:
βͺ Mixed (mucus and serous).
βͺ Open into the surface epithelium.
What is the structure of the fibrocartilaginous coat of the trachea?
- Dense CT contains 16-20 C-shaped rings of hyaline cartilage which are arranged above each other, maintain patency of the trachea and bridged at gaps between free edges by smooth muscle.
What is the structure of the adventitia of the trachea?
Dense CT contains blood vessels