Digestive system
The oral cavity:
1-The lip:
A-external surface: consist of skin(epidermis,dermis),sabeceous
gland,sweat gland and many hair follicle.
B-vermilion:consist of keratinized stratified seq epithelium,with
connective tissue rich in blood vessel.there is no sweat gl,no
sebaceous gl.
C-internal surface:consist of thin mucosa,non-keratinized
stratified seq epithelium and labial salivary gl.
The tongue
A-anterior region of the tongue
Shows many papillae like
Fungiform papillae(mushroom like)
Filiform papillae(conical)
Foliate papillae(on the side of the tongue)
Taste bud: are ovoid structures,found in many papillae but are much
more abundant in the circumvallate papillae.
Consist of:
Basal cell(on the basement membrane)
Gustatory cell(oval light nucleus,light cytoplasm)
sustantecular or supporting cell(selender dark nucleus,dark cytoplasm)
Posterior region of the tongue:
-circumvallate papillae
-lingual tonsil
esophagus
Histologically consist of :
1-mucosa
2-lamina properia
3-muscularis mucosae
4-submucosa
5-muscularis externa
6-adventitia
Important note/the difference between upper and lower
esophagus lies in muscularis externa.
1-upper esophagus:muscularis externa consist of skeletal muscle fiber
2-midder:both(skeletal and smooth)
3-lower:only smooth muscle fiber
