the Tracing food particle from start to finish UNIT #5 REVIEW HUMAN DIGESTION: 1.) Ingestion of food particle Goes into mouth a. In the mouth we have the enzyme amylase and amylase start to break down food particles. b. Salivary glands in the mouth secrete amylase 2.) Food particle is now a bolus and enters the trachea a. Continues to travel Parastolsis aids with the movement of bolus down b. Epiglottis blocks the air cavities so that food bolus does not go in the wrong direction down the esophagus. 3.) Food travels from esophagus down into the stomach a. Enters Lumen is the empty cavity that is the stomach and contains HCl acid and aids with the breakdown of the food bolus. b. Inside the stomach (i.e the lumen), the parietal cells store and secrete HCL while the chief cells secrete pepsinogen c. The muscosa is the lining of the stomach that contains the parietal and chief cells d. The food bolus mixed with acid is now called chime. e. The doorway to the small intestine is called the phyloric sphincter 4.) The chime travels through the phyloric sphincter into the small intestine a. As the chime travels through the small intestine, the lining of the small intestine now is covered with epithelial cells (which absorb the nutrients). b. Each epithelial is lined with tiny vilai which further increases the surface area ("A" from Fick's Law). c. The liver secretes bile (bile salts emulsify fat droplets) d. Gall Bladder stores extra bile e. Pancreas i. Regulatory hormones 1. Insulin Regulates sugar level If there is an abundance of sugar in the bloodstream, insulin alerts the body to convert the excess sugar into glycogen fats. or a. Glycogen animal starch (temporary glucose) 2. Glucagon Turns fats or glycogen into usable sugars/energy to be used to do work (i.e exercise) ii. Lypase Helps break down Lipids ("lyp") iii. Peptidase Break down peptides ("Pep" as in "Peptide") iv. These compounds all help to break down the chime f. Chime is being absorbed by small intestine and then is turned into chilomicrons rides in the lymph and is transported to other areas of the body from there. i. (_See below for absorption details_) g. What is left over after absorption is the waste which then travels to the large intestine. 5.) Large intestine (synonymous with "Colon") a. No other absorption besides, i. Water and vitamin K are absorbed
b. Waste continues to travel along the large intestine to the anus. 6.) Anus a. Release waste b. Excretion
ABSORPTION Proteins o Broken down by proteases Polypeptides are what are left over These are broken down by peptidases Fats o Emulsified by bile salts (enzymes involved) o Bile salts make the fat molecules more accessible to lipases Now they are small after emulsification They go through the epithelial cells go into the lymph where there are now chilomicrons with a protein coat and are transported through the body o Absorbed in small intestine, then travel as lymph into bloodstream Amino Acids o Broken down by proteases and peptidases o Nucleases help with breakdwon Sugars (carbohydrates) o Lactase o Maltase o Sucrase These three enzymes deal with the break down of sugars o Glycogen better storage of starch Break this down to use as energy not involved with breakdown.