GIT Flashcards
ORAL CAVITY
Palatine tonsils are posterior at each side of the junction of the oropharynx and mouth.
The hard and soft palates form the roof of the oral cavity. Except the teeth, all structures that project into or line the oral cavity are covered by stratified squamous epithelium nonkeratinized.
LIPS
Lips are covered by thin skin externally and lined with oral mucosa internally.The epithelium of the labial surface is translucent, so that the underlying
capillaries give red color to the lips. This transitional zone between the skin and the mucosa is the vermilion border.
HARD AND SOFT PALATE
The hard palate are bony processes covered by oral mucosa, continuous with the gingiva of the upper jaw. The stratified squamous epithelium is minimally keratinized.
The soft palate, is a posterior extension of the hard palate, formed by a layer of skeletal muscle, dense CT, and mucous glands between 2 mucous membranes.The mucous membrane on the oral surface has non-keratinized, stratified squamous epithelium, whilst the nasal side is covered by respiratory epithelium.
The soft palate prevents food and fluids from entering the nasopharynx and the nasal cavities as it is drawn up to close the nasopharynx during swallowing.
TONGUE
is divided into an anterior two thirds and a posterior
one third. The division between these regions is a V-shaped groove at the back of the tongue (sulcus terminalis).
PAPILLAE
Its roughened surface has projections, (papillae), that vary in shape and number. The most numerous are the, pointed, filiform papillae which cover the entire
dorsal surface to provide a, rasplike surface that aids in holding food on the tongue during chewing.
Occasionally taste buds may be found on fungiform papillae.
circumvallate papilae form a wide V at the sulcus terminalis, with the apex of the V directed posteriorly.
No papillae are on the posterior third of the tongue, having mucosal folds and the lingual tonsils instead
PHARYNX
Pharynx is a fibromuscular tube extending from the base of the skull to the lower level of the larynx. It is the common chamber for the passage of food, liquids, and air.
upper part, (nasopharynx), In the posterior-superior wall is the pharyngeal tonsil, (adenoids).
The middle part, (oropharynx or throat) is the common passageway for the respiratory and the digestive systems.
The lower part, (laryngopharynx), joins the esophagus at the level of the cricoid cartilage.
STOMACH
The stomach is divided into 4 regions. (1) Cardia a zone near the gastro-esophageal junction (2) A dome-shaped fundus above the level of the esophageal opening. (3) A body is about two thirds of the stomach, extending from the fundus inferiorly toward the pyloris. (4) A pylorus the most inferior region, is funnel shaped.
Duodenum
Duodenum is characterized by (1) Brunner’s glands in the submucosa, (2) many villi, and (3) terminations of the bile and pancreatic ducts. Brunner’s glands have a strongly alkaline secretion (pH 8.8-9.3), which neutralizes the acidic chyme of the stomach protecting the duodenal mucosa from autodigestion. The unique feature of the duodenum is the presence of Brunner’s glands in the submucosa
Jejunum
Villi are the tallest and lacteals are well developed for maximum fat absorption. No Brunner’s glands.
Ileum
Ileum has 1 unique feature i.e. the presence of many aggregates of lymphoid nodules (Peyer’s patches) in the LP. In addition, most of the Paneth cells reside here, no Brunner’s glands and villi are least numerous.
LARGE INTESTINE (LI)
Parts of the LI are (1) the blind pouch, the ceacum, about 5-8 cm long; (2) the appendix, a blind tube about 10 cm long, is an extension from the cecum; (3) the colon with its ascending, transverse, descending regions and the anal canal
