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Digestive System

Digestion The Breakdown (chemical or mechanical) of food
chemical digestion via enzyme utilization. 1st salivia 2nd stomach acid/digestive enzymes (CCK, Pepsin, Gastrin, Mucous
Absorption the entrance of ingested/secreted fluids, ions, nutrients, and products into the epithelial cells lining the lumen of the GI tract. (small intestine and stomach)
Digestive Enzymes in Chemical Digestion: pepsin, HCl, mucous, gastrin, maltose, sucrose, lactose, peptides, amylase, trypsin, lipase, bicarbonate(HCO3) ribonuclease, bile, bacterium.
Salivary Gland (digestive enzymes) amylase: Starch---->maltose (long chain --->glucose)
Stomach (digestive enzymes) a. Parietal cell:HCL-->break down protein b. chief cell: pepsin: proteins-->peptides (long chains of a.a. to short) c. mucous cell: mucous; lines and protects membrane d. entero-endocrine cell: gastrin--> stimulates stomach emptying
small intestine (digestive enzymes) a. amylase: starch-->glucose b. trypsin: proteins-->peptides c. lipase: Fats-->FA+Glycerol d. bicarbonate (buffer, brings down acidity of chyme) e. ribonuclease
liver/gallbladder (digestive enzymes) a. Bile: lipid-->fat droplets (break down of fat into droplets)
large intestines (bacterial, not a lot of digestion left to happen) a. carbohydrate-->H, CO2, CH4 (gases) b. proteins-->aa-->indole, H2S, Skatole-->dark poop -Gases (farts) and coloration (pigment) of poop
Salivation - triggered by the ANS - medulla oblongata-->parasympathetic DROOL - salivary gland releae saliva which is the beginning of food break down, continual process that occurs at the sense of food.
Stomach-Gastric Emptying 3-Phases -Cephalic -Gastric -Intestinal
Cephalic Phase Autonomic (parasympathetic) -Begins at salivation -controlled by PS local reflex - stomach peristalsis:contractions (growling) - stomach secretes chemicals: enzymes,and mucous in preparation for food.
Gastric Phase Autonomic (parasympathetic) & Entero-endocrine (gastrin) -phase begins as soon as food hits the stomach -stomach contractions take place, follwed by the release of chemical secretions of HCL, Pepsin and mucous. -Parasympathetic Fibers:(inc) gastrin
Food Present (gastric) Food-->inc stretch-->HCL acid secreted, dilutes food increasing PH--> inc parasympathetic--> movement of food forward (peristalsis)--> decease distention as food moves out
How is stomach acid made? g-cells produce gastrin, a hormone that facilitates the production of hydrochloric acid by parietal cells. The stomach is protected by the epithelial cells, which produce and secrete bicarbonate-rich solutions that coat the mucous.
Intestinal Phase Autonomic NS: entero-gastric reflex-movement o food from the stomach to the small intestine. Decreasing gastric emptying. Entero-endocrine: hormonal chemoreceptors secrete gastrin, CCK, secritin and GIP(slows gastric emptying and secretes insulin)
CCK liver/bile duct to triger contraction of bile duct and gallbladder for secretion of bile into the intestine (digestive enzyme).
Secritin increases bicarbonate levels pumped into the bile and is used to neutralize the PH in the intestine. (mucous cannot be used in intestine b/c it would not allow for absorption)
Factors The Stimulate v. inhibit gastric emptying stimulatory: gastrin, inc PS-->contraction, contraction of lower esophageal sphincter, inc stomach motility. inhibitory:dec distention, inc distention in duodenum, dec PSN, dec GIP,
Small Intestine (autonomic) Autonomic: parasympathetic within stomach -local neural reflex-stretch receptors -increased distention: PS back and forth movement food/absorption -decrease distention: movement of food forward Movement=paristalsis
Small Intestine (enteroendocrine) Chyme/PH-->secritin-->inc in bicarbonate levels to lower PH FA/Glucose-->CCK-->gall bladder to release bile into the intestine (digestive enzymes)
where to pancreatic and liver enzymes end up? In the stomach, and intestine
Where are the digestive enzymes of the small intestine found? pancreas, Liver
Large Intestine Nutrients already absorbed and food broken down. bacterial digestion and Poop Packing 3-Reflexes -gastroleil -gastrocolic -defication
Gastoleil after a meal, food that is in the GI tract needs to be expelled.getting rid/moving food from the small-->large intestine by relaxing the illiocrinal valve. -haustral churning-poop packing from one haustral to the next -peristalsis/mass peristalsis
Gastrocolic movement of fecal matter from the transverse colon to the descending colon. And finally through to the sigmoid. also associated with a meal.
Deification having feces in the last 8in of rectum passed the sigmoid. involuntary sphincter-internal voluntary (sort of)-external of the anus
Types of Movement in the stomach multi-unit contraction 3-layers of smooth muscle each layer contracts and distends at different times. cells controlled by a neuron contract separately.
Small & Large Intestine small: increase distention(back and fourth), decrease distention (forward movement) large: Haustral churning (movement from one haustral to the next. Peristalsis:contracting along back and fourth Mass peristalsis:strong contraction forces forward
90% of absorption occurs in _________ small intestine
How is surface area maximized? Circular folds, lining mucosa: Villi and Microvilli
Circular Folds: visible folds in the stomach that increase the surface area and absorptive properties. (folding of mucosa and submucosa)
Lining Mucosa: Villi V. Microvilli Villi-small hair like projections of mucosa (simple columnar epithelium) with absorptive phagocytitic and secretion (CCK,secritin, GIP) properties. Microvilli-forms the brush border. formed by the buckling and folding of the plasma membrane.
Brush Boarder: What is it? What digestive enzymes are found here? -microvilli and plasma proteins. -digestive enzymes at the surface allow enzymatic digestion to take place at the surface of the villi built into the plasma membrane that can have tons of different plasma proteins/enzymes.
what are the simple columnar epithelial cells on the the villi? and what are their jobs? Goblet cell-mucous secretion paneth-phagocytitic secretes lysosomes simple columnar-absorption enteroendocrine- disgestive enzyme secretion
How are carbohydrates absorbed? Differentiate between 1 and 2nd transport. carbohydrates-absorbed as monosacharrides glucose/galactose-->2nd active with Na-->monosacharides. Fructose-->fassilitated diffusion Primary: uses NA K pump Secondary: indirect ATP use: required movement before hand, or NA K pump.
How are Proteins Absorbed? Differentiate between primary and secondary transport. Proteins are broken down into amino acids, and absorbed though symport/co-transport with Na. 1. active transport with Na of antiport when H+ moves out. 2nd. dipeptides/tripeptides-->goes in with H+--> diffuses to blood capillary.
How are Lipids (shortchain) absorbed? Where do the end up? How: Small lipids/acids are lipid soluble and can pass directly though the plasma membrane. Where: End up in capillary of a vilus
Long Chain FA, Monoglycerides, fat soluble vit) How to they get absorbed? Where do they end up? How: park in brush border and enter with time through simple diffusion. FA tail in waked off Emulsification into micelles, the micelles ferry the FA across. in plasma the FA in encapsulated in a chylomicron, making it temporarily H20 Soluble.
where to FA Long chain end up after absorption? inside plasma once coated with a temporary H20 chylomicron the FA crosses out of the cell and enters into the lacteal. ex. why when your thoracic ruptures your internal cavity fills with with milky substance-it is the micelles.
Differentiate between micelles from chylomicron micelles:is/are small fat droplets that have been broken down or emulsified by bile salts/acids in the liver. chylomicron: protein coat that encapsulate FA, glycerol, Fat solube , Vitamins, aloowing temporary H20 solubility.
What % of water is absorbed small intestine vs. large intestine? 90% small 10% used to get perfect consistency.
How does the majority of H20 get into the GI Tract? Majority comes from ingestion i.e. drinking H20 all absorption in intestines happens via osmosis from lumen of the intestines through absorptive cells in the blood capillaries.
What is the Functional Unit of the Liver? Liver Lobule 50,000-->100,000 Lobules
Vascular Functions of the Liver? Storage and Filtration of Blood 3-Parts Blood Resevoir, lymph flow, retinuloendotheilia systems, sinusoids lined with kupfer cells.
Blood Reservoir-When is it mobilized? Kupfer Cells -Veins(waiting for exercise- or oxygen carrying capacity when needed increase. -sinusoids allow for the movement of blood. -venus blood sits here and pools-venus blood->inc exercise->inc blood
Lymph Formation-hydrostatic vs. osmotic pressure -increase in interstitial fluid movement, lymphatic will pick up extra interstitial fluid to a point, however the excess not picked up causes swelling of organs. -excess fluid-parethonial cavity fills with lymphatic,ascuites=result swollen belly
arterial hydrostatic pressure: increase in plasma, decrease in interstitial
Venal: osmotic pressure: increase in plasma proteins
Altered Flow: Heart Failure: blood that is not moved forward causes a block back up to the liver. causes excess increase in hydrostatic plasma fluid to the hepatocytes.
(dec)Plasma Proteins: decrease in plasma proteins due to diet, causes liver malfunction=increase in interstitial fluid. (osmotic pressure decrease)
Reticuloendothelial: What is the role of Kupffer Cells? Kupffer: found in the sinusoids are fixed phagocytitic cells. play a role in killing bacteria that comes from the GI tract. Also play a role in the removal of RBC's
What are the components of Bile? bile salts/cholesterol PH 7.6-8.6 water, bilesalts, cholesterol, a phospholipid called lecithin, bile, phagocytic cells, pigments, and several ions.
Digestive Secretion=________ What does it do? bile salts/lecithin; emulsify and break down fats
What is enterohepatic circulation? the cycling of bile salts secreted by hepatocytes into bile, re absorption by the ilieum and resecreation into bile.
Excretory Components excretory components are things that are not broken down elsewhere and are forced to the broken down in the GI tract. -bilirubin is a bi-product
What is Bilirubin a breakdown product of? heme
Differentiate between free versus conjugated bilirubin? Free Bilirubin:heme broken down->bilirubin what is released is free bilirubin Conjugated Bilirubin:converted bilirubin that is attached to gluagonic acid and sulfates in the liver by hepatocytes-->when secreted in bile it cause the variation in color.
What are the 3 types on Jaundice? 1. prehepatic/hemolytic- (inc)RBC destruction and (Inc)Free bilirubin. 2. Hepatic Jaundice:Free bilirubin that is not converted to conjugated bilirubin Free->(dec)conversion->(inc)Free Bilirubin 3. Extrahepatic Jaundice/Post Hepatic:
Why is Cholesterol in Bile? no real reason for being in bile except for dietary intake and (inc) levels is no big deal because it will just be reabsorbed in the GI tract.
Why does inc cholesterol in gallbladder cause problems? Gall Stones-caused by increase clumping of cholesterol in the gall bladder Hepatic Artery-->gal bladder-->bile salts-->bile
Carbohydrate Metabolism in the liver? stores glucogen. converts galactose and fructose(flows from BS to liver directly)into glucose. Maintenance in BG: a (dec)in glucose will then (inc) the breakdown of glycogen to glucose resulting in release of glucose in blood stream.
Lipid metabolism in the Liver? 1. oxidation of fatty acids into acetyl-coA to either be used as energy or sent to other boody cells. 2. form lipoproteins (transport lipids coated in protein) 3. Lipid Synthesis: Cholesterol and storage of fat 4. steroid breakdown:testosterone/
Steroids? Cholesterol=precursor -liver responsible for steroid breakdown and production -Anabolic Steroids: synthetic derivative of testosterone-can't be broken down properly leads to heart failure due to inc levels of cholesterol.
Protein Metabolism in the Liver? 1. removal of Nitrogen group to be left with C,O,H. 2. once deaminated ATP production or gluconeogenesis aa->glucose and ketonesis aa->FA 3. NH3(ammonia)->Urea 4. Formation of Plasma Proteins: osmotic pressure 5.synthesis of non-essential AA:heme
Which Clotting Factors are produced by the liver? 2, 7, 9, 10 VII, IX, X Vit K
Why is Vit. K important to clotting? normal clotting depends on adequate levels of Vit. K and the synthesis of of 2,7,9,10 and prothrombin factors VII,IX,X
How is Vit. K absorbed? Vit. K is produced for daily intake by bacteria in the gut. Fat-Soluble Coated in a micelles made of bile i.e. cholesterol
What vitamins and minerals are stored in the liver? Iron-For heme Copper-Results in Anemia-transporter of iron in the body.
What things does the liver remove/excrete? alcohol-alcohol dehydrogenase breaks down into aldehyde. antibiotics-penicillin, arythromyosin Lipid Soluble Hormones: Testosterone/anabolic steroids, T3/T4, biogenic amines
Liver Problems coma-high levels of ammonia jaundice-yellow skin, increase free bilirubin anemia-clotting factor heme/dec rbc acitis-dec plasma proteins ICF swollen testicular cancer-cant break down testosterone inc levels of testosterone=dec sperm=shrunken nut
Created by: gshenrich