Gastrointestinal system Flashcards
(84 cards)
What is the histology of the GI tract?
LUMEN -> MUCOSA (membrane lining the GI tract which secretes mucus ) -> SUBMUCOSA (connective tissue layer which contains blood vessles, lumph vessles and nerves)-> MUCULARSIS (smooth muscle + one circular longitudinal muscle) -> SEROSA(connectiive tissue which secreates fluid outside of the GI tract)
What are the main structures in the GI/ digestive tract tract?
WHERE FOOD PASSES THROUGH THE BODY - Oral cavity// tongue// Pharynx (“passageway from head and neck involved in both respiratory and digestive system)// Oesophagus //Stomach
// Small intestine //Large intestine
Rectum/ anus
What is the epithelium of the pharynx?
Ciliated pseudostratified columnar epithelium (nasopharynx)// moist stratified squamous epithelium (oropharynx and laryngopharynx)
What is the function of the large intestine?
reabsorb water // compacts intestinal contents into faeces// absorbs vitamins / stored feacel material // house >700species of bacteria
What is the lining of the oesophagus?
moist stratified squamous epithelium
What is the function of the peritoneal folds (mesenteries)?
connects organs to each other or to the abdominal wall
What are the 3 sections of the small intestine?
Duodenum (c-shaped found at adjacent to the pancreases at the start of the small intestine )// jejunum (connects duodenum to ileum )// ileum (extends into large intestine)
What are 4 simple columnar epithelium types which cover the villi of the small intestine and their function?
ABSORBATIVE -> digestive enzymes // GOBLET -> mucus // GLANULAR OR PANETH -> lyozomes // ENDOCRINE -> hormones
What are the main segments of the large intestine?
CECUM -> COLON (ascending limb-> transverse colon -> descending colon -> sigmoid colon ->)RECTUM = ANAL CANAL
What is the epithelium lining of the large intestine ?
MUCOSA - simple columnar epithelium // no villi or plicae// this mucosal lining is formed into straight tubular glands (crypts)
What is a plicae?
a fold or wrinkle within the epithelial tissue
What are the two sphincters of the anal canal?
internal anal sphincter (involuntary ) and external anal sphincter (skeletal muscle) // it is the circular layer of muscoularis which thickens to form these structures
what is a sphincter ?
A ring-shaped muscle that relaxes or tightens to open or close a passage or opening in the body
What are the main sphincters within the GI tract?
Upper oesophageal sphincter // pyloric s// ileocecal valve // internal anal sphincter
What makes up the oral cavity?
boundaries / cheeks /lips / palate and tongue
What is an ion dependent carriers?
protein channel/ carrier which transports molecules dependent ion concentrations
Describe secondary active transport?
Alike primary active transport, uses ATP, portein channels and electrochemical gradients // Unlike primary channels it also uses cotransporters
What is meant by absorption ?
Small molecules move through an epithelial barrier into underlying blood or lymphatic vessels
What is the difference between both secondary and primary active transport?
BOTH - ATP hydrolysis // carrier protein // uses electrochemical gradient //// ONLY SECONDARY ACUVE TRANSPORT uses cotransporters
Where does the majority of absorption occur in the GI tact ?
90% in small intestine( small inetsine -> blood -> lymph vessle)
What is the difference between a carrier and cotransporter protein?
CARRIER - transports one molecule at a time // COTRANSPORTER- transfers two molecules at a time
What does the NA+ /K+ ATPase on the basolateral membrane move?
3NA+ inside the cell for every 2K+ out
What are the two types of carbohydrates?
POLYSACCHARIDES- long chain monosaccharides/ can be digestible (starch ) or non digestible (fibre) sources = rice, pasta, cereal/// SUGARS - shorter chain found in fruits, vegetables and dairy
Where is carbohydrates broken down in the GI tract?
MOUTH - saliva breaks down starch to maltose // PANCREASE - pancreatic enzymes breaks down starch to maltose // small intestine microvilli converts oligosaccharide (saccharide polymer containing many monosaccharides) to monosaccharides