si session digestive system spring 2010 for dr. wright’s bio 6 class designed by pyeongsug kim...
TRANSCRIPT
SI SessionSI Session
Digestive system
Spring 2010
For Dr. Wright’s Bio 6 ClassDesigned by Pyeongsug Kim ©2010 [email protected]
Picture from http://www.eregimens.com/regimens/Digestion_Regimen.htm
What are the organs of the digestive system and what do they do? What are some of the enzymes of the digestve system; where are they synthesized; where in the digestive system do they actually function, and what food molecules do they break down?What substances are secreted by what cells in the stomach?What food molecules are absorbed by the stomach?Where in the small intestine do digestion and absorption take place?
What structures in the small intestine facilitate absorption?What happens in the large intestine? Why are there bacteria in the large intestine and what do they do?Liver function: what is the purpose of, and how, does the liver
Produce and secrete bile?Detoxify blood (what does it remove from the blood)Store and release food moleculesMake plasma proteins (what are they and what do they do)
What is the purpose of the gall bladder?What is in pancreatic juice and what does it do? What cells in the pancreas are exocrine cells? What stimulates the secretion of pancreatic juice?What “arm” of the autonomic nervous system controls digestion?
Designed by Pyeongsug Kim, ©2008Picture from: http://www.cartoonstock.com/directory/b/bowel_movement.asp http://www.telegraph.co.uk/science/science-news/3303035/Scientists-find-hormone-to-stop-over-eating.html
Digestive systemDigestive systemResponsible for….-Food intake-Breaking eaten food down into its monomer molecules, absorbing the monomer molecules into the body-Eliminate the undigested wastes from the body
DigestionDigestion
-Hydrolysis of macromolecules(food molecules:carbohydrates,
protein, fat, nucleic acid) into monomers: Glucose, amino acid, fatty acids… ____________
-catalyzed by specific enzymes. Digestive enzymes are made mostly by the pancreas and the
small intestine. -absorbed through the intestinal mucosa enter the blood or lymph.
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Picture from http://legacy.owensboro.kctcs.edu/gcaplan/anat2/notes/Notes8%20Digestive%20Physiology.htm
Catabolism
*Only the monomers from the foods are allowed to pass into the bloodstream.
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Oral cavity : Starch(a long chain) is hydrolyzed into shorter polysaccharide chains.Stomach : Significant digestion occurs but not fully digested to monomers.Small intestine : Most of the digestion and most of the absorption of water, monomers, and ions.Duodeum : Receives the acid chyme from stomach and digestive chemicals(enzymes) from all 3 accessay organs.Large intestine : The final water and ion absorption from the feces (Chyme after the small intestine) accurs Small intestine : Fat globules are emulsified by the detergent action of bile
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MouthMouth-___________(chewing) of food mixes it with
saliva from salivary glands.
-Enzyme: ______________
-A formation of a bolus of food
Mastification
StomachStomach-ingested food is churned; mixed with ____.
-pepsinogen converted to pepsin
__________________
-Store food; initiate the digestion of protein
-Forms and churns ______.
-Rugae
-Pylorus sphincter
HCl
Protein-digesting enzyme
chyme
EsophagusEsophagus-Wavelike contraction: _________.
-Esophageal sphincter
Peristalsis
Salivary amylase
Secretions of the stomachSecretions of the stomach-mucosal surface forms gastric pits that lead into gastric glands.Mucus - goblet cellsHCl - parietal cellsPepsinogen (pepsin)- chief cellsGastrin- G cellsEntrochromaffin-like- histamine, serotoninSomatostatin- D cells
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Intrinsic factor____________ - parietal cells (necessary for absorption of vitamin B12)
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Small intestineSmall intestine-Absorption for carbo. Lipids, amino acids Ca2+…
-to increase surface for absorption
______________
-Contraction
peristalsis & ___________
-Enzymes
Disaccharidase, peptidase, Phophtase-Most food molecules are absorbed in __________________-Bile salts, water, electrolytes in _____.
Micorvilli & villi
segmentation
Large intestineLarge intestine-Absorption for water, electrolyte, and minerals
-Little or no digestion
-_________________: produce Vit k and folic acid Bacteria (microflora)
duodenum and jejunumileum
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LiverLiver-Largest internal organ-Functional unit: lobules
-produces and secretes bile (via gall
bladder) which facilitates digestion of fat.
-Modifies the plasma concentrations of
proteins, glucose, triglyceride, and ketone
bodies.
-Detoxifies the blood Chemical alternation
Phagocytosis
Production of urea or other less toxic molecules
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Liver(Cont’d)Liver(Cont’d)
-Carbohydrates of metabolism glucose –>glycogen or glycogen glucose
glucogenesis~ produce glucose from amino acid or
lactic acid
-Lipid metabolism synthesis of triglycerides and cholesterol
excretion of cholesterol in bile
production of ketone bodies from fatty acids
-Protein synthesis albumins, plasma transport proteins
clotting factors(fibrinogens, prothrombin, etc)
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Gall bladderGall bladder
-stores and concentrates bile
-release to duodenum via common bile
duct
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PancreasPancreas-Secrete both exocrine(_____________) and endocrine(______________).
Endocrine into the blood.
Alpha cell – glucagon Beta cell - insulin
Exocrine: _______________ into dudenum: trypsin, amylase, lipasePancreatic juice
Pancreatic isletPancreatic acini
↑Blood glucose
In Beta cell↑insulin secretion
In Beta cell↑insulin secretion
Cells uptake glucose
Liver/muscle: Glucose Glycogen
Adipose tissue: Glucose Triglyceride
↓Blood glucoseInsulin↓Blood glucose by stimulating… -cellular uptake of glucose -conversion of glucose to glycogen and fat
Pancreatic juice(exocrine)Pancreatic juice(exocrine)-Pancreatic acini
-Contains water, bicarbonate, digestive enzyme
Enzyme: trypsin(for protein), amylase(for starch),
lipase(for triglycerides)
-Activation trypsin triggers activation of other pancreatic enzymes
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Secretin and CCK(cholecystokinin)Secretin and CCK(cholecystokinin)
-Duodenal hormones
-Stimulate the secretion of pancreatic juice
-Secretin ↑HCO3 production in pancreas; ↑HCO3 secretion into bile in liver
secreted in response to below pH < 4.5 in duodenal
chyme is rapidly neutralized by alkaline pancreatic juice ↓Secretin
-CCK secreted in response to protein and fat of chyme in duodenum stimulates the production of pancretic enzymes:trypsin,amylase,lipase
stimulates contraction of gall bladder to eject bile.
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Picture from http://www.bio.miami.edu/~cmallery/150/neuro/neurophysiology.htm
Designed by Pyeongsug Kim, ©2008
Parasympathetic effect in digestive system-Mouse -Saliva secretion and thin-Stomach –increase secretion-Intestine – increase secretion-GI tract – stimulate motility-Pancreas – stimulate of exocrine secretionsTable 9.4 in the 8th ed.
Picture from http://www.sodahead.com/entertainment/favorite-cartoon-sidekickanyone/question-419997/