Digestive System Flashcards
what does the mouth do in the digestion system ?
mechanical breakdown of food, package food into bolus and some enzymes are secreted to help break down food.
what does the esophagus do in the digestion system ?
peristalsis to move food down into the stomach and some mechanical breakdown
what does the stomach do in the digestion system ?
chemical and mechanical breakdown of food through enzymes, gastric juices, mucous and muscle contractions
what does the small intestine do in the digestion system ?
nutrient absorption and peristalsis
what does the large intestine do in the digestion system ?
water reabsorption and formulation of fecal waste removal
what does the rectum do in the digestion system ?
sphincter that is going to allow for fecal matter to be expelled
what does the anus do in the digestion system ?
exit site for waste
what are the layers of the gastrointestinal tract?
Mucosa, submucosa, muscularis and serosa/adventia
what is the enteric plexus?
autonomic nerve plexus from esophagus to anus
describe what the mouth does?
taste buds allow for different tastes and mixes for with saliva
describe what the esophagus does and the components ?
moves food from mouth to stomach. upper third is voluntary skeletal muscle allowing for swallowing and bottom third is smooth muscle which is involuntary
what does saliva do?
helps in mechanical digestion and lubricates mouth and allows to package food into bolus at the back of the mouth
controlled by sympathetic and parasympathetic factors
what is peristalsis?
controlled by mesentric plexus of nerves. the action of moving food down the via esophagus opposing contraction
what is segmentation?
local mixing of chyme that is released by stomach
what are the two sphincters in the esophagus?
upper esophageal and lower esophageal
what are the two phases of swallowing?
oropharyngeal and esophageal
what is oropharyngeal swallowing?
bolus of food is forced toward pharynx, pharynx contracts while respiration is inhibited (stops choking) and spligottis slides downwards
what is esophageal swallowing?
bolus of food enters esophagus, esophagus relaxes, peristalsis occurs moving food toward lower esophageal sphincter
describe the stomachs function?
muscular organs stores food, secretes digestive enzymes and juices, mixes food with juices and propels partially digested food into small intestine
what are the 4 concepts in gastric motility ?
swallowing, motilin, secretion and gastric mixing
what is the role of swallowing in gastric motility?
causes fundus (top of stomach allowing food to enter). facilitated by gastrin (stimulates acid secretion) and cholecystokinin (alkaline fluid).
what is the role of motilin in gastric motility?
increases rate of digestion by increasing peristalsis
what is the role of secretion in gastric motility?
decreases peristalsis - cholecystokinin inhibits
what is the role of gastric mixing in gastric motility?
retropulsion - mixing
The _______ nerve stimulates gastric emptying
vagus
what are the 3 phases of gastric secretion?
cephalic phase - stimulated by thought, smell and taste
gastric phase - stimulated by distension of the stomach (full/empty)
intestinal phase - stimulated by histamine and digested protein
what is gastrin?
peptide hormone for stimulating gastric acids formation
what are paracrine pathways?
cell signalling to stimulate gastric acids
what is the fundus do?
helps the with intrinsic factors (ie vitamin absorption)
what is the role of mucous?
lubricates and protect lining of esophagus and stomach and stimulated by prostaglandins.
what are prostaglandins?
active lipid compounds
what is the duodenum and what does it do?
first part of small intestine: lowers toxicity of chyme that enters the common bile duct and lymphatic system. 10” long.
what is the jejunum and ilium and what does it do?
2nd and 3rd part of small intestine: has villi and microvilli for increase surface area for absorption of nutrients into blood flow
what is the peritoneum and what does it do? what are the two types?
membrane surrounding organs of abdominal and pelvic cavity
2 types
visceral - covering organs
parietal - external within the cavity
what is the Paritoneal cavity?
space between visceral and parietal layers
what are the two layers of smooth muscle in the digestive tract?
longitudinal (outer) and circular (inner)
intestinal digestion in the stomach
HCl and pepsin
small intestine digestion
pancreatic enzymes, intestinal enzymes and biles salts
what are the 3 portions of the colon
ascending, transverse and descending
the pouches of the colon are called _______.
Haustra
where does the blood supply comes from in the digestive system?
superior and inferior mesenteric arteries
What role does the GI tract have in immunity?
mucosal secretions produce antibodies IgA. cells produce antibiotic peptides and lysosomes important in mucosal immunity
what is a Peyers Patch?
collection of lymphocytes, plasma cells and macrophages - produce antibody IgA
what is splanchnic blood flow?
provides blood flow to digestive organs
how is splanchnic blood flow altered in parasympathetic mode?
blood flow is normal
how is splanchnic blood flow altered in sympathetic mode?
no/limited blood flow –> digestion is inhibited
what does the gallbladder do?
store and concentrate bile between meals
what does the pancreas do?
produce factors to aid in digestion of carbs and sugars
what does hepatocytes do in the liver?
bile production
what is hepatic portal circulation?
circulation of blood when it doesn’t travel through the heart. directs blood from gastrointestinal tract to esophagus and rectum.
what does bile do?
breaks down lipids in the duodenum by travelling through the common hepatic duct.
what is enterohepatic circulation?
circulation of biliary acids, bilirubin from liver to bile followed by entry to small intestine.
liver –> hepatic duct –> common bile duct –> small intestine
what is bilirubin ?
by product of destruction of aged RBC in the spleen and is used by hepatocytes and secreted by bile
what are the 5 functions of the liver ?
metabolism, detoxification, production/excretion of bile, storage of blood, and storage of minerals and vitamins.
describe the exocrine pancreas?
composed of acinar cells that secrete enzymes and alkaline fluids that aid in digestion
how is the blood supplied to the pancreas?
branches of celiac and superior mesenteric arteries
what is a trypsin inhibitor?
prevents activation of proteolytic enzymes while in the pancreas
where is enteric kinase secreted ?
duodenal mucosa - activates inactive enzymes
