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75 Cards in this Set
- Front
- Back
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What activates immune response?
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Macrophages, Dendritic Cells, B/T Lymphocytes
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Name the layers within the mucosa
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Mucous epithelium
lamina propria muscularis mucosa |
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What is the function of the submucosal plexus?
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gland secretion
regulate blood flow |
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What is the function of the myenteric plexus?
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To increase:
- muscle tone - intensity of contractions To Decrease: - sphincter muscle tone |
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What is the Ileocecal valve and its function?
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Sphincter separating ileum (Small intestine) and cecum (large intestine)
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What enzyme opens the ileocecal valve?
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gastrin
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What makes up the Enteric Nervous System?
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The myenteric and submucosal plexus'
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What triggers 'slow waves' in the GI?
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Interstitial cells of Cajal (ICC) , also called pacemaker cells
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What are varicosities?
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branches of nerves within muscle cells, and they secrete neurotransmitters
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What happens during a depolarization of the membrane potential?
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-Spike (-40mV), motor neurons release neurotransmitters
-calmodulin + MLCK initiate muscle contraction |
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When norepinephrine is secreted, this causes the resting membrane potential to ______
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hyperpolarize
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What are the External Influences on the GI tract?
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1) ANS
2) hormones 3) emotional control |
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Which branch of the autonomic nervous system is responsible in aiding digestion?
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Parasympathetic
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Which hormones are primarily for secretion in the GI tract?
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CCK, Secretin, Gastrin
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How does neural communication in the gut work?
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Afferent neurons send axons to prevertebral ganglia,
-interganglionic neurons -> fast impulses -postganglionic neurons -> return signal to GI |
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Describe steps of the gastrogastric reflex?
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1) Baroreceptors send info via vagus nerve when food enters mouth
2) Vagovagal reflex (signals return) 3) Stomach movemement/secretion is stimulated |
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Secretagogues increase secretion of?
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Acetylcholine, Gastrin, Histamine
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Anti-secretagogues increase secretion of?
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PGE2, norepinephrine
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Peristalsis is controlled by the ________
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myenteric plexus
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__________ is the type of movement in the small intestine
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segmentation
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What is the migrating motor complex (MMC) ?
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Strong contractile waves thru entire gut, cleanse the lumen of pathogens and bacteria
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When food moves too fast through the intestines, this results in
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diarrhea
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What is the ileogastric reflex?
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distension of distal ileum sends signal to stomach, no more room
slowing gastric emptying |
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What is the gastroileal reflex?
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Stomach telling the ileum to empty
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Colonileal reflex?
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distension in the colon, no where to go
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What is the defecation reflex?
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It is initiated by gastro/duodenal distension
Internal anal sphincters = relax External anal sphincters = under voluntary control Up to 20cm of colon can contract at once |
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Where is most of the water you drink absorbed in the GI tract?
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Small intestine, approximately 92% of water you intake is absorbed here
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What are the functions of the saliva in the oral cavity?
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1) moisten (mucin acts as lubricant)
2) antibacterial properties (lysozomes, Immunoglobin A) 3) Digestion (amylase for glucose breakdown) |
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What type of epithelium lines the stomach?
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simple columnar
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What type of epithelial cells are found within the gastric pits of the stomach and what do they secrete?
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Goblet cells (mucous)
Parietal cells (HCl, intrinsic factor) Chief cells (pepsinogen) Endocrine cells: ECL (histamine) G Cells (gastrin) D Cells (Somatostatin) |
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Secretagogues do what?
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Increase the secretion of acetylcholine, gastrin and histamine
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Antisecretagogues do what?
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Increase the secretion of PGE2, norepinephrine
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How can the stomach prevent acid secretion?
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With Histamine blockers such as Tagamet, Pepcid
Also proton pump inhibitors such as Prevacid |
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Where is vitamin B12 absorbed?
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In the Ileum
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What initiates cephalic phase of secretion control?
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Smell, taste, thought
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What happens in the cephalic phase of secretion control?
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medulla oblongata signals enteric nervous system via the vagus nerve
enteric neurons stimulate parietal cells --> acid production |
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Gastrin from the stomach stimulates _________ secretion
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HCl
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Histamine from the stomach stimulates _________ secretion
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acid
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What follows the cephalic phase?
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Gastric phase
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What is the gastrogastric effect?
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Mucous, HCl, gastrin, intrinsic factors, pepsinogen, all of these start to get secreted into lumen of stomach when food is present
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What is secreted during the intestinal phase and why?
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Secretin is released to inhibit parietal cell inhibition
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Describe the 4 steps of the regulation of gastric secretion
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1) Peptides/AA's and vagus nerve stimulate G cells (which produces Gastrin)
2) The gastrin hormone and vagus nerve stimulate ECL cells (which produce histamine) 3) Histamine stimulates parietal cells (which produce HCl) 4) Low pH inhibits acid production by D cells (Somatostatin hormone) |
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What is the purpose of the endocrine pancreas?
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to control blood sugar levels with insulin
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Pancreatic Islets produce what?
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Insulin (beta cells)
Glucogen (alpha cells) |
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What is insulin used for?
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uptake of sugar
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Where do secretions occur in the exocrine pancreas?
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pancreatic duct
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Exocrine pancreas juice is made up of two components, ______ which is mainly ________ and ________ which consists of _________
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aqueous, bicarbonate
enzymatic, proteolytic enzymes which are released as zymogens |
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Trypsin is used for the digestion of
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proteins
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Which nerve controls pancreatic secretion?
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vagus nerve
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Which hormone stimulates pancreatic enzyme secretion?
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CCK
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CCk production is stimulated in the pancreas when
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fatty acids are in the duodenum
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Secretin in the pancreas is released when
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high acid chyme presence in duodenum
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Trypsin activates these 2 enzymes
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Procolipase
Prophospholipase |
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Where is bile produced, and how much is produced on a daily basis?
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in the liver, 500ml a day
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What hormone stimulates gallbladder emptying?
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CCK
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Which hormone increases bile production?
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secretin
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Bile acids are made by
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hepatocytes of liver by oxidation of cholesterol
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Bile acids are usually conjugated with
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taurine
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Where are bile acids reabsorbed?
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ileum
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ASBT
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Important transporter in intestinal bile clearance
located on apical membrane of distal ileum promotes secondary bile acid absortion |
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LBP
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used for transcellular movements of bile acids,
forms a complex with ASBT to absorb bile |
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What happens when bile acids enter the colon?
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diarrhea
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T-ASBT transports bile in?
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oocytes, uses incholangiocytes in the ileum and kidney
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OST is a bile transporter found in?
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Ileum
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Immature cells do what, and mature cells do what?
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Immature = secrete
Mature = absorb |
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What do paneth cells in the small intestine secrete?
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cryptidins, defensins (antibacterial)
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Small intestine secretion contains these three molecules
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Cl (ATP pumps), Na follows by diffusion, Water follows by osmosis
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Reduced water secretion, greasy stool and lower fat absorption chronicle which disease?
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Cystic fibrosis
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When does secretion in the small intestine take place?
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only when food is present
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What is the purpose of the large intestine?
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to absorb a lot of the water and secrete mucous to hold feces together
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Gastrin is triggered by ________, and it stimulates _______
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peptides and/or distension
acid secretion in stomach |
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Histamine is triggered by ______ , and stimulates
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peptides via gastrin
acid secretion |
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Somatostatin is triggered by _______ and it _________
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H+ ions
slows acid secretion and motility |
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Which transporters does glucose enter the intestine with?
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Na+ on SGLT
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Which transporter does glucose exit on?
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GLUT5
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