Upper GI: Oral Cavity to Esophagus Flashcards
1
Q
A
Lip
-
outer cutaneous surface (left)
- thin skin
- epidermis
- underlying dermis and hair follicles
- sebaceous glands and sweat glands
- skeletal muscle in the core of the lip
-
orbicularis oris muscle
- closes the mouth and puckers the lips
-
orbicularis oris muscle
- thin skin
-
inner oral mucosa (right)
- thick nonkeratinized stratified squamous epithelium with an underlying lamina propria
- Deep to the lamina propria
- small salivary glands (labial glands)
- secretions → surface of oral cavity → moisture and lubrication
- small salivary glands (labial glands)
-
vermillion (red) border
- between outer cutaneous surface and inner oral mucosa
- “tougher”, dry border (lacks glands)
- where lipstick is applied
- stratified squamous epithelium (which may or may not be lightly keratinized)
- lacks hair follicles
- tall connective tissue papillae underlying
- red→ epithelium translucent with rich capillary blood supply in papillae underneath
2
Q
A
Hard Palate
- anterior roof of mouth (the soft palate is located on the posterior roof of
the mouth) -
stratified squamous epithelium (which may or may not be
keratinized)- together with underlying lamina propria → masticatory mucosa
- provides a surface for tongue to press up against during chewing, swallowing and phonation
- together with underlying lamina propria → masticatory mucosa
-
mucus-secreting palatine glands
- submucosa
- minor salivary glands
- swallowing and lingual movements → lubricating oral mucosa.
3
Q
A
Anterior Tongue
-
sulcus terminalis
- V-shaped groove separating anterior 2/3 of tongue from posterior 1/3 of tongue
- 3 main surface projections (called lingual papillae) found on the tongue
- filiform papillae
- fungiform papillae
- circumvallate papillae
4
Q
A
Filiform papillae
- the most numerous of the lingual papillae
- no taste buds but are mechanical in function
- abrasive coating on the tongue → cleaning action (complemented by some of the anti-bacterial components of saliva)
- pointed ends which are covered by layers of keratin
- lamina propria underneath each filiform papillae projects secondary
connective tissue papillae into the base of the filiform papillae
5
Q
A
Fungiform papillae
- less numerous
- mushroom shaped; have taste buds on their upper surface
- (sour, sweet, bitter, salty and umami)
- parakeratinized epithelium (keratinocytes retain their nuclei)
- small secondary connective tissues papillae project into it from underlying lamina propria
- key feature in differentiating fungiform from filiform papillae
6
Q
A
Posterior Tongue
- circumvallate papillae
- large and shaped like cones, with the broader part projecting above the
surface of the tongue - covered by stratified squamous epithelium and contain numerous taste buds
-
Salivary glands (von Ebner’s glands)
- empty serous secretions into space at base of each circumvallate papillae
- flush materials from base of papillae → taste buds “refreshed”
7
Q
A
circumvallate papillae
8
Q
Salivary Glands
A
3 major salivary glands
- parotid
- serous secreting
- largest, produce ~30% of saliva
- sublingual
- mixed sero-mucous
- smallest, produce ~5% of saliva
- submaxillary (aka submandibular) glands
- mixed sero-mucous
- 2nd largest, produce ~60% of saliva
- ~1200 mL of saliva per day
Functions of Saliva
- lubrication and protection of oral cavity
- aiding in digestion and serving immune roles (eg antibacterial components)
9
Q
A
Parotid Gland
- purely serous gland
- separated into lobes and lobules by septa that arise from connective tissue capsule
- cells typically serous in appearance
- secretions drain along a series of ducts that differ histologically throughout the length of the ducts
10
Q
A
Parotid Gland
11
Q
A
Sublingual Gland
- mixed sero-mucous glands
- a connective tissue capsule sends septa into the glands, separating them into lobes and lobules
- mucous acini, serous acini and mixed sero-mucous acini
- lighter staining, larger mucous cells capped with crescent-shaped serous demilune of flattened serous cells
12
Q
A
Submaxillary Glands
- mixed sero-mucous glands
- a connective tissue capsule sends septa into the glands, separating them into lobes and lobules
- mucous acini, serous acini and mixed sero-mucous acini
- lighter staining, larger mucous cells capped with crescent-shaped serous demilune of flattened serous cells
13
Q
A
Esophagus
- distensible tube that connects pharynx and stomach
-
4 layers
- mucosa
- submucosa
- muscularis externa
- adventitia
14
Q
A
Esophagus
15
Q
A
Esophagus Mucosa
- epithelial lining
- underlying lamina propria
- muscularis mucosae
- aka mucus membrane
-
non-keratinized stratified squamous epithelium
- protect against abrasion, friction and injury as masticated food passes through the esophagus
- underlying lamina propria
- loose CT with nerves, capillaries and lymphatic channels that support the avascular epithelium
- layer of smooth muscle → muscularis mucosae
- localized contractions/movements of the esophagus
16
Q
A
Esophagus Submucosa
- lies underneath muscularis mucosae
- irregular dense connective tissue
- rich in both blood and lymphatic vessels
- glands in the submucosa of the esophagus
- produce an acidic mucin
- aids in lubrication as masticated food passes by
17
Q
A
Esophagus Muscularis Externa
- double layer of muscle (inner circular and outer longitudinal)
- gross contractions
- composition of these two muscle layers changes along the length of the esophagus:
- upper 1/3 both layers → involuntary skeletal muscle fibres
- middle 1/3 → internal layer is smooth muscle and the outer layer is skeletal muscle
- distal 1/3 both layers → smooth muscle
18
Q
A
Esophagus Adventitia
- typical: loose CT, adipose tissue, nerves, blood vessels
- anchors esophagus to neighbouring structures
- majority of esophagus is covered externally by an adventitia (only the short segment below the diaphragm is covered with a serosa)
- rapid spread of metastatic cells from esophageal tumours → poor survivability of esophageal cancer
