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26 Cards in this Set
- Front
- Back
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Alimentary Canal |
canal from mouth to anus
-everything in between mouth and anus is called the lumen, and it doesn't get out of the lumen until absorbed into the body |
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Digestion Pathway |
Mouth
Pharynx
Esophagus
Cardiac Sphincter
Stomach
Pyloric Sphincter
Duodenum |
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Mouth |
Function
chew=masticate
Saliva Enzymes
1) Amylase: breaks up carbohydrates into disaccarides
2) Lipase: breaks up fats into di and triglycerides
3) Lysozyme: breaks down bacterial cell walls |
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Pharynx |
Throat
-bollus of food and water travels down pharynx
-constructed from 2 tubes the esophagus and trachea |
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Epiglottis |
cartilage flap that blocks food from going down trachea when it is going to the esophagus |
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Esophagus |
tube that empties into the stomach
*lined in smooth muscle
Peristalsis involuntary contraction of smooth muscle that forces food down the esophagus |
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Cardiac Sphincter |
keeps food from coming out of stomach |
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Stomach |
Function
-stores, digests food
-lined in smooth muscle
-pH 2.0
Digestion
HCl: PARIETAL CELLS
-hydrolizes peptide bonds (breaks proteins into peptides, and polysaccarides into smaller saccarides)
-hydrolizes glycosidic bonds
Pepsin: CHIEF CELLS
-produced as a zymogen
-gets activated by pH
-proteolytic enzyme that breaks peptide bonds via catalysis
-Proteolytic enzymes= proteases and petidases
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Pyloric Sphincter |
valve between stomach and SI
Function
-keeps food from going into SI until is has room
Regulation
-controlled by the ANS
-Endocrine: closes in response to cholesisitokinen
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Zymogen |
inactive precursor to protein
all proteases have to be produced as zymogens
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Stomach Regulation |
Gastrin -leads to secretion of HCl and Pepsin -made by G-cells in stomach
Histamine -stimulates secretion of HCl
PSNS -upregulates stomach digestion -rest and digests -SNS inhibits digestion |
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Liver: Secretion of Bile |
Bile -produced from hydrophopbic cholesterol -1 liter per day, reabsorbed in the illeum -absorbtion of fat soluble vitamins
1) Digestion of Lipids -emulsifies fats (breaking up fat droplets into small fat droplets called micelles) which creates surface area for the digestive enzyme lipase)
2) Gallbladder -stores bile releases bile to duodenum bia common bile duct
3) Regulation of Glucose -makes sure glucose in in your system
4) Lipid Metabolism
5) Cori Cycle
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Liver Regulation of Glucose |
Glycogenolyis -breaks down glycogen into glucose
Glucogenesis -opposite of glycogenolysis -converts pyruvate into glucose
GLUCAGON, CORTISOL, INSULIN - cause liver to produce glucose through glycogenolysis or glucogensis
1) Glucagon: opposite of insulin
2) Cortisol: stress response uses glucose
3) Insulin: created in the pancreas -takes glucose out of the blood stream at the liver where it is stored as glycogen |
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Cori Cycle |
converting lactic acid produced by muscles into glucose |
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Pancreas Fucntions |
1) produces insulin
2) produces digestive enzymes which are sent to duodenum via pancreatic duct
3) acts as an endocrine gland
4) produces hormones
5) regulates pH change from stomach into duodenum
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Pancreatic Digestive Enzymes |
Amylase -breaks down starch (polysaccarides) into disaccarides
Proteases -break down proteins -don't get activated until they are in the duodenum
1) Trypsin
2) Chymotrypsin
3) Carboxypeptidase
Lipases -break down triaceylglycerides (TAG) into monoaceylglycerides (MAG) and FFA's
Nucleases -break up nucleic acids
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Pancreas and pH regulation & Hormones |
-pH in the Duodenum 7-8, bolus turns into chyme (pH 2) once it mixes with gastric juices in the stomach
Bicarbonate Secretion -secretion of bicarbonate (weak base) is stimulated by secretin, allows for rapid pH change Stomach to Duodenum
Hormones -made in the islets of langerhans
1) Glucagon: secreted when you are starving
2) Insulin: secreted after eating, takes glucose out of blood and stores as glycogen
3) Somatostatin:
-inhibits digestion by inhibiting HCl secretion -inhibits secretion of gastrin, histamine, and cholescitokinen
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Pancreatic Proteases |
Function -break peptide bonds -cut in a specific location (specific amino acid sequence)
1) Trypsin -gets activated by enterokinase in duodenum
2) Chymotrypsin -once trypsin gets activated by enterokinase, trypsin cleaves part of chymtripsinogen making chymotrypsin
3) Carboxypeptidase -activated by enteropeptidase in the SI -cleaves off terminal acids |
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Duodenum activation of pancreatic enzymes |
produces cholesistokinen which activates pancreatic digestive enzymes |
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Endocrine vs. Exocrine |
Endocrine: secretes hormones into blood stream, don't pass thru a duct
Exocrine: secreted out of body, into the lumen of alimentary canal and pass thru duct
*enzymes in pancreas go to the lumen of your body by passing thru the pancreatic duct |
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Pancreas: Islets of Langerhans |
area in the pancreas that makes hormones
1) Alpha Cells: make glucagon
2) Beta Cells: make insulin
3) Delta Cells: make somatostatin
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Small Intestine |
Structure
Duodenum: -duodenum does must of digestion
Illeum and Jejunum: -specialized absorption of b vitamins
Villi and Microvilli: -create large surface area for absorption -brush border for enzyme secretion
Digestion 1) Carbs: pancreatic disaccarides to monosaccarides
2) Proteins: pancreatic di and tripeptides to free amino acids
3) Fats: bile and lipase break down fats enough so SI doesnt have to break further (MAG) (FFA)
Absorption -absorbs monosac, aminos, (MAG) (FFA)
Enzyme Production 1) Enterokinase: excocrine produced by duodenum to activate trypsin
2) Brush Border Enzymes
Hormone Secretion 1) Cholesistokinin (CCK) -secreted in the capillaries, tells pancreas to give SI digestive enzymes -food in duodenum promotes secretion of CCK
2) Secretin -too much acidity inititates duodenum release of secretin
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Microvilli and Intestinal Epithelial Cells of SI |
Microvilli
house brush border cells which produce enzymes, folds on folds
Epithleial Cells
-form tight junctions so nothing passes thru SI cell wall
-food gets absorbed through epi cells on the lume side, then makes it out the other side and is taken up by capillaries or lymph |
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Small Intestine Digestive Enzymes |
Brush Border Amylases
-carbohydrate metabolism -break down dissacrides from pancreatic digestion into smaller monosaccarides for absorption ex: sucrase breaking down sucrose
Brush Border Proteases -breaks down di and tri peptides of pancreatic digestion into free amino acids
Fats -FFA and MAG's are already small enough to diffuse right into endothelial cells |
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Small Intestine Absorption |
Monosaccarides
glucose (monosaccaride) absorbed into endothelial cells via symport
symport: secondary active transport -glucose is coupled with sodium down the gradient and go into epithelial cells
Amino Acids
same as carbs using symport and facilitated diffusion -have carboxylate and ammonium terminus making them very polar so they need a transport protein
Monoacelglycerides
1) hydrophobic so they can freely diffuse into epithelial cells
2) once in epi cells converted back into TAG's and get packaged into chylomicrons (big balls of lipids and cholesterols) chylomicrons end up in lacteal (lymphatic system)
3) Chylomicrons emptied thru thoracic duct into venous circulation
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Large Intestine |
Illeocecal Junction Separates the SI from the LI
Pathway
Cecum-Colon(ascending,transverse,descending)-rectum-anus
Function
-Absorption: of h2o, electrolytes(ions), and certain vitamins
-Bacteria production
-metabolize and produces vitamin k
-formation of feces: compacts feces in the rectum
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