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114 Cards in this Set
- Front
- Back
What is digested by bile in the liver?
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fats
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What is digested in the stomach? By what enzyme?
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proteins by pepsin
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Where does lipase occur? What does it digest?
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Stomach
Fats |
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What are the regions of the digestive system?
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Mouth or oral cavity
Pharynx Esophagus Stomach Small intestine Large intestine Anus |
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what are the accessory organs to the G.I. tract?
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Liver and pancreas (secrete enzymes into the GI tract)
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Where does the most absorption occur?
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small intestine
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what enzyme breaks down sugar? From where?
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amalase
glands i.e. salivary glands pancreas |
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What are the functions of the digestive system?
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Mastication, propulsion (deglutition, peristalsis) mixing, secretion, digestion, absorption, elimination
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describe deglutition
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swallowing - both voluntary and involuntary process
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How long does food stay in the stomach? What's happening to it?
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3-4 hours - moves back and forth from superior to inferior parts to thoroughly digest
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what is mixing?
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Segmental contraction that occurs in small intestine
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what functions does secretion have
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Lubricate, liquefy, digest
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describe absorption
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Movement from tract into circulation or lymph - mostly in the small intestine
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describe elimination
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Waste products removed from body
voluntary and involuntary |
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peristalsis is done by which muscles?
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circular muscularis
longitudinal muscularis |
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what motion does the circular muscularis do?
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does the squeezing
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what motion does the longitudinal muscularis?
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coordinates the squeezing
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what does the serosa do?
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secretes fluid to prevent friction with other organs
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what is the most apical layer in the GI tract?
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mucosa
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what is the most basal layer?
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the serosa
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what are the two functions of the mucosa
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1. protection - composed of epithelial cells, rapidly dividing can be abraded and disrupted but rapidly replace
2. secretion - many enzymes are secreted by the mucosa in the stomach, intestine, liver, pancreas. |
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All enzymes are released through the ________
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mucosa
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which nervous system regulates the digestive system?
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the peripheral nervous system directly controls digestion
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What happens during emergency situations in regards to the nervous control of the digestive system?
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the parasympathetic nervous system overrides the enteric nervous system to stop digestion
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the enteric nervous system does what
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Coordinates peristalsis and regulates local reflexes
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Teeth are responsible for what in the digestive system?
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mechanical digestion
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what is the hardest part of the tooth?
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enamel
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what is responsible for holding the root of the tooth in place?
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cementum
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what is contained in the pulp of the tooth?
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nerve and blood supply
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what enzyme is contained in saliva? What does it break down?
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salivary amylase
breaks down starch |
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where does deglutition occur
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in the pharynx
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where is the epiglottis?
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in the pharynx
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what is the esophagus function
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passageway for food from pharynx to stomach
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the esophagus contains two _____, the ________ and _________
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sphincters
upper lower |
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what are the three phases of deglutition?
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1. voluntary phase
2. pharyngeal phase 3. esophageal phase |
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describe the voluntary phase of deglutition
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Bolus of food moved by tongue from oral cavity to pharynx
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describe the pharyngeal phase of deglutition
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Reflex: Upper esophageal sphincter relaxes, elevated pharynx opens the esophagus, food pushed into esophagus
Reflex: Epiglottis is tipped posteriorly, larynx elevated to prevent food from passing into larynx |
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describe the esophageal phase of deglutition
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food moves into espohagus thru the upper esophageal sphincter.
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The epiglottis if usually tipped
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superiorly
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the pharyngeal and esophageal phase of swallowing are __________
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involuntary
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what is the gastroesophageal opening?
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also known as the lower esophageal sphincter or cardiac
Opening from esophagus to stomach |
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what is the pyloric sphincter?
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the opening from the stomach leading into the duodenum
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what are the layers of the stomach from outermost to innermost?
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serosa/visceral peritoneum, muscularis - (outer longitundinal, middle curcular, inner oblique) submucosa, mucosa,
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what are rugae?
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folds in stomach when empty
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what are gastric pits?
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openings for gastric glands in the stomach
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what do the gastric pits contain?
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surface mucous cells
mucous neck cells parietal cells chief cells endocrine cells |
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what 2 types of cells are needed to digest proteins?
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parietal cells -
chief cells |
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what do parietal cells secrete?
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hydrochloric acid
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what do chief cells secrete?
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pepsinogen
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what does pepsinogen need to be activated? What is activated pepsinogen called?
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hydrocloric acid activates it
- becomes pepsin |
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what does pepsin digest?
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proteins
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describe the stomach endocrine cells structure and what they secrete, where?
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ductless - secrete gastrin hormone into the bloodstream. gastrin hormone regulates GI secretion.
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when gastrin increases, secretin ________ in the _________
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decreases in the small intestine
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what do chief cells secrete?
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pepsinogen
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what does gastrin do?
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increases stomach activity
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what are the three phases of gastric secretion?
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cephalic
gastric intestinal |
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describe the cephalic phase of gastric secretion
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BEFORE FOOD - taste or smell of food triggers gastrin hormone release, increased stomach activity
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describe the gastric phase of gastric secretion
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DURING FOOD - Food is present = increase activity caused by distention
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describe the intestinal phase of gastric secretion
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END of FOOD in STomach - a decrease in pH causes secretin released by small intestine into blood, which travels to stomach to decrease stomach activity
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gastrin ___________ stomach activity
secretin __________ stomach activity |
increases
decreases |
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what is the site of the greates amount of digestion and absorption?
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the small intestine
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what are the divisions of the small intestine?
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Duodenum
Jejunum Ileum |
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what are the modifications of the small intestine? What their function?
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Circular folds or plicae circulares, villi, lacteal, microvilli
function to increase surface area |
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what are the cells of the small intestine mucosa?
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Absorptive, goblet, granular, endocrine
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what do the goblet cells do?
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secrete mucus
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the endocrine cells of the small intestine secrete _____________ which ___________ stomach activity
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secretin
decreases |
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the small intestine relies on enzymes from the __________ and _______________
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liver and pancreas
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what does the mucus secreted by the small intestine do?
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Protects against digestive enzymes and stomach acids
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what digestive enzymes does the small intestine secrete?
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Disaccharidases: Break down disaccharides to monosaccharides
Peptidases: Hydrolyze peptide bonds Nucleases: Break down nucleic acids |
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what do peptidases do?
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breack down proteins by hydrolyzing peptide bonds
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what do disaccharidases do?
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breakdown sugars - deiaccharides into monosaccharides
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the duodenal glands of the small intestines are stimulated by what?
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Stimulated by vagus nerve, secretin, chemical or tactile irritation of duodenal mucosa
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where does the cystic duct originate
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the gallbladder
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the common bile duct joins the __________________
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pancreatic duct
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What are the functions of the liver
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Bile production
Salts emulsify fats, contain pigments as bilirubin Storage Glycogen, fat, vitamins, copper and iron Detoxification Hepatocytes remove ammonia and convert to urea |
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bile is stored and concentrated in the
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gall bladder
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the gall bladder dumps into the ____________ from the _________________
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small intestine
common bile duct |
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the common bile duct is composed of what?
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the cystic duct leaving the gall bladder and the hepatic duct leaving the liver combine to form the common bile duct which dumps into the small intestine
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the pancreas containes both _________ and ___________ cells
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endocrine and exocrine
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what are the secretions of the exocrine cells of the pancreas (what does pancreatic juice contain)?
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Trypsin
Chymotrypsin Carboxypeptidase Pancreatic amylase Pancreatic lipases Enzymes that reduce DNA and ribonucleic acid |
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what pancreatic secretions break down proteins?
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Trypsin
Chymotrypsin Carboxypeptidase |
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what pancreatic secretion breaks down sugars?
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Pancreatic amylase
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what pancreatic secretion breaks down fats?
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pancreatic lipases
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what are the name of the exocrine cells in the pancreas that produce digestive enzymes?
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acini cells
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pancreatic islets produce
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insulin and glucagon
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pancreatic intercalated duct cells produce what?
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aqueous component of pancreatic juice (water that mixes with enzymes) They release water into the duct
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acinar cells produces what
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the enzymatic component of pancreatic juice.
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the pancreas dumps into the ________________
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small intestine
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what is the major function of the large intestine?
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resorption of water
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the internal anal sphincter is __________
the external anal sphincter is _____________ |
involuntary smooth muscle
voluntary skeletal muscle |
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what happens at the pumps in the large intestine?
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Exchange of bicarbonate ions for chloride ions to decrease pH from acidic bacteria
Exchange of sodium ions for hydrogen ions to reabsorb H2O ( water leaves GI tract and goes back into body) |
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fats, proteins, and sugars are absorbed by ____________
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epithelial cells
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fats are transported by the ___________
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lymph system
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protein and sugar are transported in the __________
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blood
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what are the polymer, the digestive enzymes, and the resulting monomer in protein digestion?
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polymers = proteins & polypeptides
digestive enzymes = pepsin, trypsin, chymotrypsin, carboxypeptidase monomer = amino acids |
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what are the polymer, the digestive enzymes, and the resulting monomer in sugar digestion?
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polymer = polysaccharides, starch
digestive enzyme = dissaccharidase and amylase monomer = monosaccharides |
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what are the polymer, the digestive enzymes, and the resulting monomer in fat digestion?
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polymer = fat triglyceride
digestive enzyme = bile (emulsifies) and lipase monomer = triglycerides and fatty acids |
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what are transported by the lacteal (lymph) system?
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triglycerides and fatty acids
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lipase comes from the
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pancreas
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how are lipids transported into the lacteal system?
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Emulsification by bile breaks down large lipid droplets to small
Lipase breaks down lipid into fatty acids and glycerol moves into intestinal epithelial cell by simple diffusion and is then a triglyceride that gets coated with a protein coat to form a chylomicron, then exocytosis expells chylomicron out of cell and into lacteal system. |
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Why lipids transported in the lacteal system?
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because lacteal is big enough to allow the larger molecules.
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why is the protein coat added to the triglyceride?
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to make it more water soluble
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How are carbohydrates transported into the blood?
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Polysaccharides broken down to monosaccharides
Monosaccharides taken up by active transport or facilitated diffusion and carried to liver Glucose is transported to cells requiring energy |
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what are two types of chylomicrons? What do they do?
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LDL
Transports cholesterol to cells HDL Transports cholesterol from cells to liver |
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Low density lipoproteins form the ____________
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the fat plaques in arteries
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LDL have _____ fat and ______ protein
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high fat
low proteins |
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HDL have ________ and ___________
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low fat
high protein |
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how are proteins tranported into the blood
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amino acids are brought into the intestinal epithelial ell by secondary active transport and the sent out via active transport into the capillary
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Water
In the GI tract, water can move in either direction across wall of small intestine depending on _________ |
osmotic gradients
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describe fat breakdown
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bile from liver emulsifies large fat down to triglycerides. then lipase can break the bonds, releasing the fatty acids.
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carbs
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