Newest Bios 256 Midterm Exam Review Packet-1.

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 BE ABLE TO IDENTIFY ...

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 BE ABLE TO IDENTIFY EACH ORGAN ON THE IMAGE ABOVE. 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 Be able to identify all parts of the GI tract What are the histological significances of the GI tract? The GI tract consist of 4 layers: Mucosa- Divides into 3 layers Epithelium – Surface Epithelium Lamina Propria – Connective Tissue Muscularis Mucosae – Smooth Muscle Submucosa- Areolar Connective Tissue Muscularis- In all GI tract organs except the stomach Serosa ENZYMES originating in the oral cavity What are the functions of 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 - What are the components of saliva? Among these polynucleotides, what is digested in the oral cavity? (proteins, lipids, nucleic acids, carbohydrates) 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 What is the function of stomach acid? Define gastric secretion. What are the components of gastric secretion? 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 - Why is it important for the Brunner’s gland to secrete alkaline fluid? Describe the cells that line the GI tract. (Hint: in each region, there are different cells) What kind of muscle tissue is found in the GI tract? 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 - What is the importance of villi? PANCREATIC JUICE Pancreatic Amylase - Breaks down carbohydrates - Converts polysaccharides to a-dextrose, maltose and maltotriose Pancreatic Lipase - Breaks down lip