Histology Of The Gastrointestinal Tract Flashcards
What is the epithelium of the mouth?
Stratified squamous non- keratinising epithelium
What is the epithelium of the lips?
Mainly same as mouth- stratified squamous non-keratinising
But at borders becomes skin- stratified squamous keratinising
What does the lips submucosa contain?
Collagen and elastic fibres
Glands
Skeletal muscle
Small blood vessels that keep the lips moist
What is the epithelium of the tongue?
On ventral surface: stratified squamous non- keratinising
On dorsal surface: stratified squamous keratinising (due to constant abrasion on this surface)
What is contained within the tongues submucosa?
Coarse bundles of skeletal muscle running in different directions
Mixed sero-mucous salivary glands
Lymph nodules, particularly in the posterior third of the tongue
What are the two different types of skeletal muscle within the tongue?
Extrinsic fibres- insert onto the lower jaw
Intrinsic fibres- attach to the fibrous connective tissue underlying the mucosa
What are papillae?
Complex folds on the dorsum of the tongue, which are lined by pale staining taste buds
What are the three types of papillae?
Tall, pointed filiform papillae (most numerous)
Mushroom shaped fungiform papillae
Dome-shaped circumvallate papillae
Where are the three types of papillae found?
Tall, pointed cover the whole of the anterior two- thirds of the tongue
Mushroom shaped are found at the tip and sides of the tongue
Dome- shaped are found in a v-shaped row separating the anterior two thirds of the tongue from the posterior third
What do parotid glands produce?
A watery enzyme-rich secretion (serous secretion)
Enzyme- alpha amylase
Where are the parotid glands found?
Anterior to the ear on both sides of the face and enter the mouth adjacent to the first upper molar teeth via ducts
What nerve passes through the parotid gland but doesn’t innervate it?
CN 7- facial nerve
What else can be found embedded in the parotid glands?
Large lymph nodes
How can you notice the acini of the parotid glands?
Spherical clumps that resemble bunches of grapes
Basal cytoplasm filled with RER
What are the ducts of the acini lined by?
Simple cuboidal epithelium that may become stratified at their distal end
Where are the sublingual salivary glands found?
Beneath the tongue with ducts secreting into the floor of the mouth either side of the frenulum of the tongue
What do the sublingual glands secrete?
Sticky mucus rich secretion that lubricates the mouth and the bolus of food
What do sublingual glands look like?
Pale staining- mucus granules
Swollen with oval nucleus at base of the cell
Surround pink staining simple cuboidal ducts
Where are the submandibular glands found?
Subcutaneously, below the mandible, either side of the tongue and discharge onto the frenulum of the tongue
What type of gland is the submandibular gland?
Mixed sero-mucous
How can you recognise a submandibular gland acini?
Has mixed dark staining cells- serous secretion
And pale staining cells- mucous secretion
What do the parotid and submandibular glands also secrete?
Epidermal growth factor that promotes growth of the GI tract epithelium
What is the epiglottis the boundary for?
The oropharynx and laryngopharynx
What is the epiglottis covered by?
Stratified squamous non-keratinising epithelium
What can you see within the epiglottis’s submucosa?
Elastic cartilage, lymph nodules and salivary glands
What are the four layers of the GI tract?
Innermost mucosa
Submucosa
Muscularis propria
Serosa (in some regions)