BIOS 256 A&P IV FINAL EXAM REVIEW PACKET 100% CORRECT GUIDE FOR A+ SCORE {ACCURATE SUMMER-FALL SESSION} (Latest UPDATE 2023/2024) A&P IV Final Exam Review Packet

DIGESTIVE PROCESSES 1. Ingestion 2. Digestion (mechanical and chemical) 3. Motility (mixing and propulsion) 4. Secretion 5. Absorption 6. Defecation GI TRACT AND ACCESSORY DIGESTIVE STRUCTURES GI TRACT INNERVATION • Autonomic NS o Parasympathetic NV (enhances digestion) o Sympathetic NV (inhibits or slows down digestion) • Enteric Nervous System o Submucosal plexus o Myenteric plexus ENZYMES originating in the oral cavity Salivary glands Parotid glands (under the cheek bones) Submandibular glands (under the mandible) Sublingual glands (under the tongue) • All secrete SALIVA, which contains: o Mostly water o Ions o Buffers o Lysosyme o Salivary amylase Salivary Amylase (made by the salivary glands) - Break down carbohydrates - Converts Polysaccharides to monosaccharides, maltose, maltotriose and alpha-dextrins - Deactivated by stomach acid Lingual Lipase (made by the lingual glands of the tongue) - From lingual glands of the tongue - Break down lipids - Activated by HCl of stomach - Converts triglycerides to fatty acids and monoglycerides THE SIGNIFICANT CELLS OF THE STOMACH AND THEIR SECRETIONS (GASTRIC JUICE) Parietal Cells - Secrete HCl - makes the chyme acidic - kills bacteria - denaturing (unfolding) proteins - activates pepsin along with lingual lipase. - Secrete intrinsic factor, which allows for absorption of vitamin B12 Chief Cells - The major stomach cells - Secrete pepsinogen, which is activated (by stomach acid) and becomes pepsin, a peptidase - Pepsin breaks down proteins - Secrete gastric lipase - breaks down triglycerides into monoglycerides and fatty acids G Cells - Secrete Gastrin (hormone): contracts cardiac sphincter; loosens pyloric sphincter; promotes stomach motility; promotes secretion of pepsinogen from chief cells and HCl from parietal cells Mucous Cells - THEY SECRETE MUCOUS - Mucous forms a protective barrier against acidic chyme THE SIGNIFICANT CELLS OF THE SMALL INTESTINE AND THEIR SECRETIONS Paneth Cells - Secrete lysozome The Enteroendocrine Cells - S Cells - Secrete secretin in response to acidic chyme, promoting release of HCO3- rich pancreatic juice; secondarily, secretin slows down secretion of gastric juice. - K Cells - Secrete GIP (glucose-dependent insulinotropic peptide) - slows down secretion of gastric juice - stimulates insulin secretion - CCK Cells - Secrete cholecystokinin in response to amino acid and fatty acid - CCK stimulates digestive enzyme-rich pancreatic juice - relaxes the sphincter of Oddi - slows gastric emptying - promotes a feeling of satiety - causes contraction of the gallbladder - CCK and Secretin enhance each other Brunner’s Glands - Secrete alkaline rich mucus to counter acidic chyme - Located in the duodenum The Brush-border - Brush-border enzymes are inserted into the plasma membranes of the microvilli in the small intestine Alpha-dextrinase - Alpha-dextrins to glucose Maltase - Maltose to glucose Lactase - Lactose to glucose and galactose Sucrase - Sucrose to glucose and fructose Enterokinase - Converts trypsinogen to trypsin Aminopeptidase - Further breaks down amino acids and peptides Dipeptidase - Dipeptides to amino acids Phosphatases & Nucleosidases - Nucleotides to nitrogenous bases PANCREATIC JUICE Pancreatic Amylase - Breaks down carbohydrates - Converts polysaccharides to a-dextrose, maltose and maltotriose Pancreatic Lipase - Breaks down lipids - Converts triglycerides to fatty acids and monoglycerides Trypsin - Breaks down proteins - Converts proteins to peptides Chymotrypsin - Breaks down proteins - Converts proteins to peptides Carboxypeptidase - Breaks down proteins - Removes amino acid at carboxyl end of peptides Elastase - Breaks down proteins - Converts proteins to peptides Ribonuclease - RNA to nucleotides Deoxyribonuclease - DNA to nucleotides ABSORPTION OF NUTRIENTS - Most absorption (90%) occurs in small intestine, specifically duodenum. - Microvilli have a capillary bed and a lacteal to allow for absorption into the general circulation. The shape and structure of villi and the pliae circulares (circular folds) increase surface area, which allows for more absorption. - Lipids - Lipids need to be emulsified by amphipathic bile salts and then they are surrounded by bile salts in a spherical structure called a micelle. The micelle transports the dietary lipids and other hydrophobic particles in the chyme to the absorptive cells where they enter via simple diffusion - Most of the lipids recombine into larger structures, lipoproteins called chylomicrons. The chylomicrons are too big to diffuse into blood capillaries, thus they are taken up into lacteals. The lacteals merge with larger lymphatic vessels and eventually bring the lipids back into circulation after they empty into the right lymphatic duct. - Amino acids, dipeptides and tripeptides - Brought into general circulation via active transport mechanisms - Carbohydrates - Facilitated diffusion - Fructose - Secondary active transport - Glucose and galactose