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58 Cards in this Set
- Front
- Back
what organs are in the middle GI tract?
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the small intestine
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What are the 3 portions of the small intestine?
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1.duodenum - contains the openeing for the bile duct and main pancreatic duct
2. jejunum - where food is digested and abosrbed 3. ileum - where food is digested and absorbed |
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What are the lorgans of the lower GI tract?
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1. cecum
2. colon 3. rectum 4. anal canal |
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What are the layers of the GI wall?
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1. mucosal layer - inner layer, produces mucus that lubricates and protects inner surfacse
2. submucosal layer - (support) consisits of connective tissue containing blood vessels, nerves and strictures that secrete digestive enzymes 3. circular layer 4. longitudinal layer 5. peritoneum - outer layer |
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what are the sublayers of the peritoneum?
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1. parietal peritoneum - in contact with abdominal wall
2. viseral peritoneum - covers stomach and intestines.. protects underlying tissue by secreting serious fluid to moisten and lubricate |
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What is the mesentery?
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a double fold of peritoneum that suspend th jejunum and ileum. Contains blood vessles, nerves and lymphatic vessels that supply intestinal wall
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What is peristalsis?
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propelling movement from proximal to distal in stomach and small intestine. coordinated circulat nad lenthwise contractions
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What does gastresophageal spincter do?
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contraction prevents fastric reflux and hyatus of diaphram. relaxes during swallowing
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what do epithelial cells in esophagus secrete?
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mucus
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where is protien digesteion initated?
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stomach
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what is largest endocrine organ in the gody?
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the GI tract
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What does cholecytokinin do?
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secreted in duodenum and jejunum when products of protein digestion fatty acids are present. Stimulats contraction of ballbladder and secretion of pancreatic enzymes. inhibits food untake
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What is Gastrin?
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hormone produced by G cells in stomach. Stimulates gastric acid secretion
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What is Secretin?
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hormone secreted by mucosa of duodnum and jejunum that inhibits gastric acid secretion... release is stimulated by entry of acidic chyeme into small intestine
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What are the two types of glands in the stomach?
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1. oxyntic glands (or gastric) - in proximal section
2. pyloric glands - in antrum segment (distal |
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what do oxyntic/gastric gland secrete?
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1. HCL (parietal/oxyntic cell)
2. pepsinogen (chief /peptic cells)... convereted to pepsin by HCL 3. intrinsic factor 4. mucous |
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what do pyloric glands secrente
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- mostly mucus
-some pepsionogen and gastrin |
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why is intrisic factor important?
what cells secrete it? |
-produced by parietal/oxyntic cells
-neseccary for B12 absorption |
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What do parital/ oxyntic cells secrete?
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HCL and intrinsic factor
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what do peptic or cheif cells secrete?
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pepsinogen
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what regulates gastic secretions?
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1,.parasympathtic impules throug vagus nerve and gastrin enhance gastric secretions
2. sympathetic impulses triggered by food/ acid in small intestine inhibits gastric secretions |
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what effect to parasympathetic impusles have on digetion?
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enhance gastric secretion by stimulateing gastrin release.
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where does the breakdown of fats begin?
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the small intestine
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what is main absorption function of large intestine?
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water reabsorption by osmosis
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what enzynes digest carbs?
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1. amylase (mouth and pancrease)
2. |
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what is major site of fat absorption?
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uppper jejunum
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what enzyme breaks down fats?
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Lipase from pancrease
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where are proteins digested and by what enzymes?
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1. pepsin (stomach)
2. Pancreatic enzymes: - trypsin -chymotrypsin -carboxypeptidase |
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what are contents of pancreatic juise?
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1. bicarbonate ions - nuetralize acidic chyme
2. digestive enzymes: -amylase -lipase -nucleases -proteolytic enzymes: trypsin, chymotrypsin, carboxypepsidase |
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what type of pancreatic cells produce digestive enzymes?
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Acini cells
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when are pancreatic digestive enzymes sent to duedunum?
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When acidic chyme eneres duodenum, mucous membranse releases secretin and cholecytokinin, which stimulate release of pancreatic juice to neutrailize acidic chyme
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what does protiens and fats in chyme stimulate?
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release of cholecytokinin by duodenom, which stimulates relsease of pancreatic juice
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what are the functional units of the liver?
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Hepatic lobules - hepatic cells radiationg out from a central vein, separated by vascualr channals (sinusoid). Hepatic cells modify blood composition by picking up chemicals
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what are the major functions of the liver?
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1. metabolism of carb, lipids and protiens
2. filters blood 3. destroys toxins 3. secretes bile - digestion |
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whawhat are sinusoids?
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vascular channels that separate hepatic cells, where blood from digestive tract brings nutrients and macrophages remove bacteria... bllod then empties into central veins
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What is calanilculus?
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where bile is released from hepatic cells and carried to bile duct, where it is taken to gall bladder
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what is the path of bile?
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hepatic cells--> cnaliculus --> bile duct --> galbladder
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what are metabolic functions of liver with sugars, proteins and fats?
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1. Sugars :stored as glycogen, converted to glucose, used to make fats
2.Proteins : synthesized from amino acids; ammonia made into urea 3. Fats : oxidized for energy, synthesized, packaged into lipoproteins |
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What is the composition of bile?
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bile salts(*only one impt for digestion)
pigments cholesterol electrolytes |
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What is function of the gall bladder?
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-stores bile between meals, then releases into small intestine when sphincter musulce contracts
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when arwhen does gallbladder realse bile?
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stiumlated by cholecytokinin
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what is the function of bile?
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1. emulsifies fats so that lipases can work effectivley
2. aids in absorption of fatty acids, cholesterol, and fat-soluable vitamins |
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what can lack of bile salts cause?
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poor lipid absorption
vitamin deficiencies |
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what happens to bile after in intestines?
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In large intestine, convereted by bacteria to urobilinogen
-some lost in feces -some reabsorbed in blood - some returned to liver - some filtered out by kidneys 00> urine |
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-What are crypt of Lieberkühn?
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glands in small intestine
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Structure of the small intestine wall:
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Mucuous membrane lined with villi: ↑surface area (250 m2); aid in mixing and absorption
-Intestinal glands between villi(crypt of Lieber |
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What are the functinos of the small intestine?
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Receives secretion from pancreas and liver
Completes nutrient digestion Absorbs products of digestion (enterocytes) Transports the residues to the large intestine |
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What do small intestine microvilli do?
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Enzymes in microvilliperform final steps in digestion:
Lactase, sucrase, amylase, maltase, αdxtrimase Villiabsorb monosaccharides, aminoacids, fatty acids, and glycerol Fat molecules with longer chains if carbon atoms enter the lacteals of the villi |
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what is the Ileocecal sphincter?
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controls movements of the intestinal contents from the small intestine into the large intestine
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what are the main functions of the large intestine?
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1. Reabsorbs water and electrolytes
2. Forms and stores feces 3. secretes mucus -little or no digestive function |
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what are enterocytes?
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- cover the villi of the small intestive and contribute to absorbtion and digestion
- secrete brush border enzymes |
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what do brush border enzymes do?
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-released by enterocytes of small intestine
- break down disachharides to monosaccarides -also breaks down polyptids |
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Protein digestion overview:
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1. Stomach: pepsinogen
-Activated to pepsin by acid in stomach -Breaks proteins into polypeptides 2. Duodenum: pancreatic trypsinogen -Activated to trypsin in duodenum -Breaks proteins into polypeptides 3. Brush border enzymes Breaks polypeptides into 2–3 aminoacidpeptides - Peptides absorbed into blood |
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--Carbohydrate Digestion overview
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1. mouth - salivary amylase
2. SI -duodenum - pancreatic amylase: poly saccarids --> di 3. Brush border enzymes: di - mono, monosac absorbed into blood |
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Fat Digestion overview"
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1. Dudenum - bile emulsifies
2. Deodenum - pancreatic lipase breaks trigly into glycerol and fatty acids 3. Jjeunum - packages fats as chylomicrons and passes to lymph |
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Glocose transport from intestinal lumen into body fluids:
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1. Both Na+ and glucose must attach to carrier before transported into the cell
2. The concentration of glucose builds up in the intestinal cell until a diffusion gradient develops→ glucose move into the body fluids -Sodium is transported out of the cell by the energy-dependent Na+/K+-ATPasepump. This creates the gradient needed to operate the transport system -Water is passively absorbed along a concentration gradient generated by the absorption of solutes |
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Digestion of which substance begins in the mouth?
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Carbohydrate digestion begins in the mouth with salivary amylase;
protein digestion begins in the stomach with pepsinogen; fat digestion begins in the small intestine with bile and pancreatic lipase |
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How would fat digestion be affected if bile levels decreased?
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It would decrease
Bile emulsifies fat so that it can be more easily digested. Decreased amounts of bile would lead to decreased fat emulsification and decreased ability to break down/digest fats |