1 Terms to know Digestive System a Nutrient substance in food needed for growth maintenance and repair b Absorption movement of a substance across an epithelium to inside the body 2 7 2020 2 Cells and permeability a Plasma membrane i Selectively permeable 1 Hydrophilic region a Phospholipids b Carbohydrate side chains 2 Hydrophobic region a Fatty acid tails 3 Hydrophilic region a Proteins ii Active transport diffusion b Membrane of the gut Apical 1 Nonpolar hydrophobic molecules can go right through the 2 Polar hydrophilic molecules cannot move through the hydrophobic tails without help 1 Lumen where food is passing through Basolateral 1 Blood basement 3 Absorption of nutrients a Macronutrient substance required in large amounts by organisms i ii i Lipids Food 1 2 Carbohydrates 3 Proteins 4 Back to the GI tract elimination a Large intestine i Runs from ileocecal valve to anus 1 Cecum 2 Appendix 3 Colon a Receives chyme from small intestine a Contains masses of lymphoid tissue Indigestible matter made into feces a Water absorbed b c Bacterial fermentation of unabsorbed nutrients d 4 regions i ii iii iv Ascending Transverse Descending Sigmoid e Left colon storage of waste and indigestible materials f Right colon absorption of water and ions 4 Rectum 5 Anal canal a Storage site for feces b Elimination of stored feces a Outside of abdominopelvic cavity b Last segment of the large intestine c d 2 sphincters Feces leave the body i ii Internal and smooth External and skeletal ii iii Large diameter No mechanical digestion 1 Microbial chemical digestion Absorption iv v Major functions 1 Absorb remaining water 2 Store indigestible material 3 Eliminate indigestible material 4 Absorb microbial metabolites vi Same 4 layers 1 Mucosal epithelium a Simple columnar epithelium mostly b Near anal canal Stratified squamous epithelium 2 No circular folds villi or microvilli 3 Intestinal crypts glands a Lots of goblet cells i i Produce a lot of mucus 1 Helps passage of feces protection 5 Accessory digestive organs a The liver i ii iii v vi Accessory GI organ Largest gland in the body Composed of 4 lobes 1 Right largest 2 Left 3 Quadrate 4 Caudate iv Main digestive function of the liver 1 Secrete bile Detoxify toxic metabolites 1 Excreted in feces or urine Stores glucose 1 Glycogen 2 Gluconeogenesis vii Makes proteins 1 Albumins viii Receives blood coming from the stomach small and large intestine 1 Does this through the hepatic portal vein 2 Hepa means liver ix Liver is composed of microscopic functional units 1 Lobules a Hexagonal like structure b Surrounded by fibrous connective tissue c Made up of hepatocytes i ii Liver cells Filter blood d Hepatocytes surround a central vein b Liver cells hepatocytes i ii Active in lipid and protein synthesis Lots of rough and smooth ER 1 Secrete a total of about 1 liter of bile daily 1 Into bile canaliculi Important role in storing glucose Important in detoxification iii iv c Bile i Made in the liver by hepatocytes ii iii iv v Excess bile stored in the gallbladder The gallbladder does not produce bile Bile leaves the liver out of common hepatic duct Bile leaves gallbladder via the cystic duct 1 During the contraction of the gallbladder vi i ii Common hepatic duct and cystic duct combine and form the common bile duct d The common bile duct Combines with pancreatic duct 1 Both pancreatic and bile duct are controlled by sphincters Forms the ampulla of vater 1 Empties into duodenum through the major duodenal papilla iii Opening of ampulla is controlled by the sphincter of oddi 1 Hepatopancreatic sphincter a Circular layer of smooth muscle e Bile composition a Protein coming from the liver that is mixed into bile i Yellow green basic solution 1 Water 2 Electrolytes 3 Bilirubin 4 Triglycerides 5 Phospholipids 6 Cholesterol 7 Bile salts a Cholesterol derivatives b Amphipathic molecules Polar hydrophilic Nonpolar hydrophobic i ii ii iii Lipids are largely hydrophobic nonpolar Hydrophobicity cannot dissolve in water Cannot form hydrogen bonds in water 1 2 Causes lipids to aggregate together a Hydrophobic effect b Fat globules iv Water is polar 1 Polar molecules dissolve in water because they form hydrogen bonds with water molecules 2 Nonpolar molecules group together in water because the water molecules form hydrogen bonds with one another v vi Bile salts emulsify lipids 1 Breaks larger fat molecules into smaller ones Essentially makes lipids soluble in aqueous solutions Enables their chemical digestion 1 2 And eventual absorption 6 The pancreas a Endocrine i ii Islets of langerhan cells secrete hormones into blood vessels Insulin iii Glucagen 1 Beta cells 2 Stimulus high blood glucose 3 Response reduced blood glucose 1 Alpha cells 2 Stimulus low blood glucose 3 Response raise blood glucose b Exocrine i ii Acinar cells secrete digestive enzymes into pancreatic duct Pancreatic juice 1 Amylases nucleuses proteases lipases 2 Bicarbonate 3 Water 7 Regulation of bile and pancreatic juice secretion a Bile salts b Secretin c Cholecystokinin d Vagus nerves i ANS