Histology Flashcards
What type of epithelium lines the oral cavity oropharynx and laryngopharynx?
Stratified squamous epithelium which is not keratanized
What lines the nasal caity and nasopharynx?
Respiratory epithelium
What type of epithelium lines the anterior 2/3rd of the tongue?
Stratified squamous epithelium, thin on ventral surface, thick with papillae on the dorsal surface
What type of epithelium lines the posterior 1/3rd of the tongue?
Covered by smooth stratified squamous epithelium which, except for the circumvallate papillae, lacks papiilae but does have substantional lymphoid aggregates in the submucosa
What are the 4 types of tongue papillae?
Fungiform
Circumvallate
Foliate
Filliform (no tastebuds - occupy much of dorsal surface)
What are the 3 parts to the mucosae of the digestive tract?
Epithelium - sits on basal lamina
Lamina propria - loose connective tissue
Muscularis mucosae - thin layer of smooth muscle
What makes up the submucosae?
Loose connective tissue
What makes up the muscularis externa?
Two thik layers of smooth muscle, an inner circular layer and an outer longitudinal layer
What makes up the serosa or adventitia?
Outer layer of connective tissue that either suspends the digestive tract or attaches it to other organs
What is present in the submucosa of the oesophagus?
Submucosal glands
What is the gastro-oesophageal junction?
Abrubt transition from stratified squamous epithelium of oesophagus to the columnar epithelium of the cardia of the stomach
What is at the bottom of the gastric pits?
Gastric glands
What lines the gastric pits?
Mucous cells
What type of gastric glands does the isthmus of the gastric pit contain?
Parietal cells
What type of gastric glands does the neck of the gastric pit contain?
Mucous and stem cells
What type of gastric glands does the base of the gastric pit contain?
Chief cells, with a few parietal cells and enteroendocrine cells
What does the chief cell produce?
Digestive enzyme secreting cell
What does the parietal cell produce?
Hydrochloric acid
What is the mucosa like in the cardia of the stomach?
Deep gastric pits that branch into loosely packed, tortous glands
What is the mucosae like in the body of the stomach?
Shallow gastric pits with long straight gastric glands
What is the mucosae like in the pylorus of the stomach?
Deeo gastric pits with branches, colied gastric glands at a higher density that in the cardia
What is the muscularis externa of the stomach?
Layer is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer. This layer aids the churning action of the stomach
What is the gastroduodenal junction?
Abrupt transition from stomach mucosa to duodenal mucosa. The inner, circular layer of smooth muslce is markedly thickened to form the pyloric sphincter
What is located within the duodenum?
Brunner’s glands in the submucosae
What is located within the jejunum?
Tallest villi, located on permanent circular folds of the mucosa and submucosa, the plicae cirularis
What is located within the ileum?
Characterized by aggregations of lymphoid follicles called peyer’s patches found in the submucosa and often extending into the lamina propria
What is an enterocyte?
Tall columnar cells with a brush border and are the principle absorptive cell
What are golbet cells?
Produce mucin to protect epithelium and lubricate passage of material
What are paneth cells?
Found at the base of the crypts of Lieberkuhn, they have a defensive function and have a role in regulating bacterial flora (secrete lysozyme and defensins)
What are enteroendocrine cells?
Produce hormones that contribute to the control of secretion and motility (gastrin, CCK, vasoactive intestinal pepide)
What are stem cells?
Found at the base of the crypts of Lieberkuhn, they divide to replenish epithleium
What is the function of brunner’s glands?
When stimulated by the presence of chyme, they produce a thin, alkaline mucous to neutralise the chyme
What are the 2 cells of the small intestine?
Absorptive cells - removal of salts and water
Goblet cells - secretion of mucous to lubricate the colon
What are crypts?
Straight tubular glands that extend down to the luscularis mucosae
What is the rectoanal junction?
A distinct junction between the mucosa of the rectum and the stratified squamous epithelium of the anal canal
Where do most of the neurones live in the GI tract?
Most of the neurones live in groups called ganglia between the two muscle layers that make up the muscularis externa
What is the myenteric plexus?
Interconnected network of fibers that controls gut motility in the muscularis externa
What is the submucosal plexus?
Second network of neurones found in the submucosa that controls the muscle of the muscularis mucosae and helps to regulate secretion in the epithelium
