Wk.10 L2 - Histology of the nasal cavity and salivary glands Flashcards
(26 cards)
What are the primary functions of the nasal cavity?
It conducts, conditions, and filters air; provides the sense of smell; and regulates the immune response to inhaled antigens.
Which type of epithelium lines the olfactory segment of the nasal cavity?
Pseudostratified columnar olfactory epithelium.
Name the four principal cell types found in the olfactory epithelium and their general roles.
- Olfactory receptor cells (detect odorants)
- Sustentacular cells (support and secrete odorant-binding proteins)
- Basal cells (stem cells)
- Brush cells (involved in sensory perception via trigeminal nerve synapses).
What unique feature do olfactory receptor cells exhibit?
They possess approximately 20 apical cilia (up to 200 µm long), a single dendrite extending into the lumen, and an axonal process that forms the olfactory nerve (CN I).
What is the role of sustentacular cells in the olfactory epithelium?
They provide metabolic support by secreting odorant-binding proteins and offer physical support to the olfactory receptor cells.
How do basal cells contribute to the olfactory epithelium?
They act as stem cells that differentiate into sustentacular cells, supporting renewal and repair.
What is distinctive about brush cells in the olfactory epithelium?
They have large, blunt microvilli and form synapses with trigeminal nerve axons (CN V) for sensory input.
What is the primary function of the respiratory epithelium in the nasal cavity?
It conducts, conditions, and filters inspired air and employs ciliary movement to transport mucus.
List the four cell types found in the respiratory epithelium.
Ciliated cells
goblet cells
brush cells
basal cells.
What is the function of goblet cells in the respiratory epithelium?
They secrete mucus to trap particles and protect the airway.
What are the three major paired salivary glands and their predominant secretory types?
- Parotid glands (serous)
- submandibular glands (mixed but mostly serous)
- sublingual glands (mixed but mostly mucous).
Where are the minor salivary glands located?
In the submucosa of buccal (cheeks), labial (lips), lingual (tongue), and palatine (back of the mouth) regions.
How do salivary glands develop embryologically?
They originate as a solid cord of oral epithelium that invades the mesenchyme, then branch into bulbous ends (acini) and undergo canalization to form ducts.
What is an acinus in salivary glands?
A grape-like blind sac composed of secretory cells (acinar cells) that produce saliva; acini can be serous, mucous, or mixed.
How do serous acini differ from mucous acini histologically?
Serous acini are spherical and protein-secreting, while mucous acini are tubular, have mucinogen vesicles, and appear pale after fixation.
What are serous demilunes and why are they observed?
They are half-moon caps of serous cells over mucous acini, often seen as a fixation artifact when mucin expansion displaces serous cells.
What is the function of myoepithelial cells in salivary glands?
They are contractile cells that help expel saliva from acini into the ducts.
Describe the progression of duct types in salivary glands from acini to the oral cavity.
- Starts with secretory ducts (simple cuboidal)
- Intercalated ducts
- Intralobular (striated) ducts
- Excretory ducts that may be stratified or pseudostratified.
What special role do striated ducts serve in salivary glands?
They contribute to the resorption of electrolytes and the modification of saliva’s fluid content.
What are the main components of saliva?
Water, proteins, glycoproteins (enzymes and antibodies), electrolytes, and bicarbonate.
What functions does saliva serve in the oral cavity?
It lubricates, initiates digestion, neutralizes acids, and helps maintain oral hygiene by clearing food debris.
How do excretory ducts differ from other duct types in salivary glands?
They are larger ducts with stratified or pseudostratified epithelium that transport modified saliva into the oral cavity.
What does the term ‘canalization’ refer to in salivary gland development?
It is the process where the innermost cells of the epithelial cords degenerate to form a lumen, creating the ductal system.
How are mucous cells distinguished from serous cells in salivary acini?
Mucous cells appear pale with flattened nuclei due to mucinogen vesicle secretion, while serous cells are rich in rough ER, ribosomes, and secretory vesicles.
