Summary break down long chain proteins, polysaccharides and nucleic acids into monomers recall hydrolysis (opposite of dehydration synthesis) (hydro-w

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3 Summary break down long chain proteins, polysaccharides and nucleic acids into monomers recall hydrolysis (opposite of dehydration synthesis) (hydro-water lysis-break apart) if not broken down, proteins which are nonself would make a big antigen invasion

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6 Input - Output digestive system invests many juices hydrolases = enzymes catalyse hydrolysis Glands with ducts - exocrine glands (vs. endocrine glands, ductless, for hormones) 800 g food IN per day, 1200 ml water 7000 ml GLANDS 50 g solid OUT, 100 g water

7 Anatomy (mouth to stomach) Mouth - teeth, lubrication salivary amylase to disaccharide maltose - starch tastes sweet (eventually) only starch digested in mouth -ase enzymes Pharynx swallowing Esophagus - bolus, peristalsis Cardiac oriface

8 An integrative story Rats cannot vomit (cardiac oriface - no reverse peristalsis). One trial learning avoid tastes which make them sick. (You too may have similar experience.) only be poisoned with a delayed reaction Warfarin (warf = Wisconsin alumni research foundation) which is an anticoagulant. (used in lower doses to prevent heart attack).

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11 Additional information parietal cell: HCl kill bacteria stop amylase chief cell: pepsinogen ---(HCl, pepsin))--> pepsin (proteolytic) optimum ph for pepsin is 2 (Inactive forms called zymogens) Heartburn antacids, ulcer Helicobacter pylori associated with ulcer very little absorption except aspirin, alcohol

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14 Additional information Pyloric sphincter regulates emptying of acidic gastric juice to duodenum. In duodenum, bile from liver and bicarbonate and enzymes from pancreas add to enzymes from small intestine

15 Intestine enzymes - lactase, maltase, sucrase, others mitosis - since cells digest themselves absorption - food and water

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18 Signalling by G-protein involving camp (covered earlier) disrupted by cholera toxin - a lifethreatening diarrhea must replace fluids - salts and glucose (as in the electrolyte coctails athletes drink like Gatorade) facilitate water absorption

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21 Protein digestion Trypsin & chymotrypsin - endopeptidases Carboxypeptidase, exopeptidase, cuts carboxy terminal. Aminopeptidase (brush border) cuts amino terminal. Di- and tri-peptidases - intracellular. Intestinal cells digest themselves, and their enzymes go into intestinal lumen.

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25 Additionally "pro..." as in "procarboxypeptidase "...ogen" as in "chymotrypsinogen peptide fragment is cut off from a larger precursor protein to make active enzyme; many examples like this in biology for instance prohormones cleaved to make active peptide hormones. Pancreas puts out bicarbonate (alkaline) to neutralize stomach acid.

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27 Liver Very few enzymes. Emulsify fats. Iron recycling. Eliminate some wastes to feces. Detoxify.

28 Detoxification Portal blood veins - hepatic portal vein "microsomal fraction" (smooth endoplasmic reticulum) has enzymes to detoxify. detoxify drugs like barbiturates (inducible). Alcohol -(alcohol dehydrogenase (ADH) )-> aldehyde - (aldehyde dehydrogenase)-> acetic acid AcetylCoA add to fatty acid chains 2 carbons fatty metamorphosis - cirrhosis.

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32 Additionally, Erythrocyte iron recycling, bile pigment (bilirubin) ->urobilinogen turns feces dark. Also colors urine. Hepatitis (disorder which spills bile into blood) - turns skin yellow (jaundice) (feces are not as dark, urine is darker)

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39 Fundamental information food stimulates gastrin gastrin stimulates gastric juice until there is a low (acidic) ph FROM DUODENUM Cholecystokinin (CCK) - liver and pancreas Secretin for bicarbonate release Enterogastrones slow gastric emptying

40 Appetite Hunger & satiety are complex LH (lateral hypothalamus) hunger center, VMH (ventromedial) satiety center, Hypothalamus - motivated behaviors Affect (perception of goodness or badness) nigrostriatal tract (bundle of nerve axons) dopamine deficient in Parkinson's disease.

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42 Recent literature ob/ob mice are leptin deficient arcuate nucleus of hypothalamus orexigenic, Neuropeptide Y (NPY) and agoutirelated protein (AgRP) anorexigenic, proopiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) leptin regulates synaptic plasticity and axon guidance