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114 Cards in this Set

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What is digested by bile in the liver?
fats
What is digested in the stomach? By what enzyme?
proteins by pepsin
Where does lipase occur? What does it digest?
Stomach
Fats
What are the regions of the digestive system?
Mouth or oral cavity
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
what are the accessory organs to the G.I. tract?
Liver and pancreas (secrete enzymes into the GI tract)
Where does the most absorption occur?
small intestine
what enzyme breaks down sugar? From where?
amalase
glands i.e. salivary glands
pancreas
What are the functions of the digestive system?
Mastication, propulsion (deglutition, peristalsis) mixing, secretion, digestion, absorption, elimination
describe deglutition
swallowing - both voluntary and involuntary process
How long does food stay in the stomach? What's happening to it?
3-4 hours - moves back and forth from superior to inferior parts to thoroughly digest
what is mixing?
Segmental contraction that occurs in small intestine
what functions does secretion have
Lubricate, liquefy, digest
describe absorption
Movement from tract into circulation or lymph - mostly in the small intestine
describe elimination
Waste products removed from body
voluntary and involuntary
peristalsis is done by which muscles?
circular muscularis
longitudinal muscularis
what motion does the circular muscularis do?
does the squeezing
what motion does the longitudinal muscularis?
coordinates the squeezing
what does the serosa do?
secretes fluid to prevent friction with other organs
what is the most apical layer in the GI tract?
mucosa
what is the most basal layer?
the serosa
what are the two functions of the mucosa
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.
All enzymes are released through the ________
mucosa
which nervous system regulates the digestive system?
the peripheral nervous system directly controls digestion
What happens during emergency situations in regards to the nervous control of the digestive system?
the parasympathetic nervous system overrides the enteric nervous system to stop digestion
the enteric nervous system does what
Coordinates peristalsis and regulates local reflexes
Teeth are responsible for what in the digestive system?
mechanical digestion
what is the hardest part of the tooth?
enamel
what is responsible for holding the root of the tooth in place?
cementum
what is contained in the pulp of the tooth?
nerve and blood supply
what enzyme is contained in saliva? What does it break down?
salivary amylase
breaks down starch
where does deglutition occur
in the pharynx
where is the epiglottis?
in the pharynx
what is the esophagus function
passageway for food from pharynx to stomach
the esophagus contains two _____, the ________ and _________
sphincters
upper
lower
what are the three phases of deglutition?
1. voluntary phase
2. pharyngeal phase
3. esophageal phase
describe the voluntary phase of deglutition
Bolus of food moved by tongue from oral cavity to pharynx
describe the pharyngeal phase of deglutition
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
describe the esophageal phase of deglutition
food moves into espohagus thru the upper esophageal sphincter.
The epiglottis if usually tipped
superiorly
the pharyngeal and esophageal phase of swallowing are __________
involuntary
what is the gastroesophageal opening?
also known as the lower esophageal sphincter or cardiac
Opening from esophagus to stomach
what is the pyloric sphincter?
the opening from the stomach leading into the duodenum
what are the layers of the stomach from outermost to innermost?
serosa/visceral peritoneum, muscularis - (outer longitundinal, middle curcular, inner oblique) submucosa, mucosa,
what are rugae?
folds in stomach when empty
what are gastric pits?
openings for gastric glands in the stomach
what do the gastric pits contain?
surface mucous cells
mucous neck cells
parietal cells
chief cells
endocrine cells
what 2 types of cells are needed to digest proteins?
parietal cells -
chief cells
what do parietal cells secrete?
hydrochloric acid
what do chief cells secrete?
pepsinogen
what does pepsinogen need to be activated? What is activated pepsinogen called?
hydrocloric acid activates it
- becomes pepsin
what does pepsin digest?
proteins
describe the stomach endocrine cells structure and what they secrete, where?
ductless - secrete gastrin hormone into the bloodstream. gastrin hormone regulates GI secretion.
when gastrin increases, secretin ________ in the _________
decreases in the small intestine
what do chief cells secrete?
pepsinogen
what does gastrin do?
increases stomach activity
what are the three phases of gastric secretion?
cephalic
gastric
intestinal
describe the cephalic phase of gastric secretion
BEFORE FOOD - taste or smell of food triggers gastrin hormone release, increased stomach activity
describe the gastric phase of gastric secretion
DURING FOOD - Food is present = increase activity caused by distention
describe the intestinal phase of gastric secretion
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
gastrin ___________ stomach activity

secretin __________ stomach activity
increases

decreases
what is the site of the greates amount of digestion and absorption?
the small intestine
what are the divisions of the small intestine?
Duodenum
Jejunum
Ileum
what are the modifications of the small intestine? What their function?
Circular folds or plicae circulares, villi, lacteal, microvilli

function to increase surface area
what are the cells of the small intestine mucosa?
Absorptive, goblet, granular, endocrine
what do the goblet cells do?
secrete mucus
the endocrine cells of the small intestine secrete _____________ which ___________ stomach activity
secretin

decreases
the small intestine relies on enzymes from the __________ and _______________
liver and pancreas
what does the mucus secreted by the small intestine do?
Protects against digestive enzymes and stomach acids
what digestive enzymes does the small intestine secrete?
Disaccharidases: Break down disaccharides to monosaccharides
Peptidases: Hydrolyze peptide bonds
Nucleases: Break down nucleic acids
what do peptidases do?
breack down proteins by hydrolyzing peptide bonds
what do disaccharidases do?
breakdown sugars - deiaccharides into monosaccharides
the duodenal glands of the small intestines are stimulated by what?
Stimulated by vagus nerve, secretin, chemical or tactile irritation of duodenal mucosa
where does the cystic duct originate
the gallbladder
the common bile duct joins the __________________
pancreatic duct
What are the functions of the liver
Bile production
Salts emulsify fats, contain pigments as bilirubin
Storage
Glycogen, fat, vitamins, copper and iron
Detoxification
Hepatocytes remove ammonia and convert to urea
bile is stored and concentrated in the
gall bladder
the gall bladder dumps into the ____________ from the _________________
small intestine
common bile duct
the common bile duct is composed of what?
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
the pancreas containes both _________ and ___________ cells
endocrine and exocrine
what are the secretions of the exocrine cells of the pancreas (what does pancreatic juice contain)?
Trypsin
Chymotrypsin
Carboxypeptidase
Pancreatic amylase
Pancreatic lipases
Enzymes that reduce DNA and ribonucleic acid
what pancreatic secretions break down proteins?
Trypsin
Chymotrypsin
Carboxypeptidase
what pancreatic secretion breaks down sugars?
Pancreatic amylase
what pancreatic secretion breaks down fats?
pancreatic lipases
what are the name of the exocrine cells in the pancreas that produce digestive enzymes?
acini cells
pancreatic islets produce
insulin and glucagon
pancreatic intercalated duct cells produce what?
aqueous component of pancreatic juice (water that mixes with enzymes) They release water into the duct
acinar cells produces what
the enzymatic component of pancreatic juice.
the pancreas dumps into the ________________
small intestine
what is the major function of the large intestine?
resorption of water
the internal anal sphincter is __________
the external anal sphincter is _____________
involuntary smooth muscle

voluntary skeletal muscle
what happens at the pumps in the large intestine?
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)
fats, proteins, and sugars are absorbed by ____________
epithelial cells
fats are transported by the ___________
lymph system
protein and sugar are transported in the __________
blood
what are the polymer, the digestive enzymes, and the resulting monomer in protein digestion?
polymers = proteins & polypeptides

digestive enzymes = pepsin, trypsin, chymotrypsin, carboxypeptidase

monomer = amino acids
what are the polymer, the digestive enzymes, and the resulting monomer in sugar digestion?
polymer = polysaccharides, starch
digestive enzyme = dissaccharidase and amylase
monomer = monosaccharides
what are the polymer, the digestive enzymes, and the resulting monomer in fat digestion?
polymer = fat triglyceride
digestive enzyme = bile (emulsifies) and lipase
monomer = triglycerides and fatty acids
what are transported by the lacteal (lymph) system?
triglycerides and fatty acids
lipase comes from the
pancreas
how are lipids transported into the lacteal system?
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.
Why lipids transported in the lacteal system?
because lacteal is big enough to allow the larger molecules.
why is the protein coat added to the triglyceride?
to make it more water soluble
How are carbohydrates transported into the blood?
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
what are two types of chylomicrons? What do they do?
LDL
Transports cholesterol to cells
HDL
Transports cholesterol from cells to liver
Low density lipoproteins form the ____________
the fat plaques in arteries
LDL have _____ fat and ______ protein
high fat
low proteins
HDL have ________ and ___________
low fat
high protein
how are proteins tranported into the blood
amino acids are brought into the intestinal epithelial ell by secondary active transport and the sent out via active transport into the capillary
Water
In the GI tract, water can move in either direction across wall of small intestine depending on _________
osmotic gradients
describe fat breakdown
bile from liver emulsifies large fat down to triglycerides. then lipase can break the bonds, releasing the fatty acids.
carbs