Gastrointestinal Tract Flashcards
What are the accessory organs?
Teeth, tongue, salivary glands, gallbladder, pancreas
Epithelium of tongue
What attaches it to the floor of oral cavity?
-Skeletal muscle covered w a layer of stratified squamous epithelium
-Thin band called lingual frenulum
What are papillae and what are the 4 types?
Small projections that the tongue epithelium are arranged into
-Filiform - no taste buds
-Fungiform
-Circumvallate
-Foliate papillae
What is the Waldyer’s ring?
Lingual tonsil + palatine tonsils + adenoids
What are the 4 layers of the alimentary canal?
1- Mucosa - inner epithelium
2- Submucosa - layer of CT
3- Muscularis externa - layer of SM - CIRCULAR AND LONGITUDINAL LAYER
4- Serosa - outer layer of CT
What are the 3 mucosa components of the alimentary canal?
- Epithelium - faces lumen, composed of simple columnar epithelium from stomach to LI and has goblet cells
- Lamina propria - thin layer of CT, blood lymphatic vessels, glands, MALT
- Muscularis mucosae - 2 thin layers of SM arranged in diff directions - inner layer is circular and outer layer is longitudinal
What kind of tissue is present in the submucosa?
-Dense irregular CT
-Contains blood and lymphatic vessels and submucosal glands
-Nerve clusters of enteric nervous system - submucosal plexus or Meissners plexus
Serosa VS Adventitia?
-Referred to as serosa in organs within peritoneal cavity and adventitia in organs outside of cavity
-Serosa - simple squamous epithelial tissue and loose CT
-Adventitia - dense irregular CT
What is present in the layers of the oesophagus?
- Mucosa - stratified squamous, non keratinized epithelium, mucous glands
- Submucosa - mucous glands and elastic fibres
- Muscularis externa - 2 layers of muscle - skeletal and smooth
Where does the mucosa change abruptly and what does it change to?
Mucosa changes from stratified squamous epithelium to glandular secretory (simple columner) mucosa at the gastro-oesophogeal junction
Which side of the stomach has greater curvature?
-Left convex - greater curvature
-Right concave - lesser curvature
What are the 5 regions of the stomach?
-Cardia
-Fundus
-Body
-Pyloric antrum
-Pylorus
What differences are present in the 4 layers of thge stomach compared to rest of alimentary canal?
- Mucosa - gastric pits (columnar cells, goblet cells), gastric glands
2.Submucosa - same - Muscularis externa - 2 layers of muscle - additional inner layer of SM in body (oblique layer)
- Serosa - same
What are the 4 main types of cells in gastric glands (deep to superficial) ?
1- Enteroendocrine cells
2- Chief cells
3- Parietal cells
4- Mucous neck cells
What are the 3 divisions of the small intestine?
Duodenum, jejunum, ileum
What is present in the mucosa and submucosa of the duodenum?
-Mucosa has villi and crypts of Lieberkuhn
Submucosa has brunners glands - produce alkaline mucous to protect duodenum
-Neuroendocrine cells secrete CCK -cholecystokinin, secretin
Where do pancreatic and common bile ducts open intp the duodenum?
Via Ampulla of Vater
What is present in the Mucosa and Mulscularis propria of the small intestine?
Mucosa - plicae circulares, villi, peyers patches
Muscularis propria - circular layer and longitudinal layer
Folds present in small inestine
Circular folds in mucosa and submuscosa
Villi in mucosa
Intestinal crypts
What kind of epithelium lines villi and crypts in the small intestine?
-Simple columnar epithelium
What do enterocytes have?
Microvilli
What types of cells are there in the small intestine?
-Enterocytes
-Goblet cells
-Paneth cells
-Neuroendocrine cells
-Stem cells
-Intraepithelial lymphocytes
What are the 4 main regions of the large intestine?
Caecum, colon, rectum, anus
Where is the appendix found?
-Attached to caecum
-composed of lymphoid tissue - suggested immunologic function
What is the colon and what are the diff parts?
-Colon is main large intestine - ascending, transverse, descending, sigmoid
What are the positions where the colon changes called?
-Right (hepatic) colic flexture
-Left (splenic) colic flexture
Are there folds present in large intestine? What kind of epithelium makes up the mucosa?
-Few enzyme secreting cells and no circular folds or villi
-Mucosa is simple columnar epithelium
Func of goblet cells and enterocytes present in large intestine - colon
Goblet cells - secrete mucus that eases the movement
Enterocytes - absorb water, salts and vitamins
What kind of epithelium is present in the colon?
Simple columnaar epithelium
What happens in the recto-anal junction?
Junction between rectum and anus
-Changes to stratified squamous epithelium
What are the 3 unique features of the large intestine?
-Teniae coli - 3 smooth muscle bands of longitudinal muscularis
-Haustra - pouches form by tonic contractions of the teniae coli - wrinkled appearance
-Epiploic appendages - small fat-filled sacs of visceral peritoneum - purpose unknown
