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Digestion Slide 2 Colorado State College Highlight: Established in 1870, Fort Collins Colorado. Ranked nationally for its science and engineering programs Slide 3 What is Digestion? The process of converting food into simpler molecules that can be absorbed by cells and used within the body. Slide 4 The Digestive System Mainly Includes: The mouth Esophagus Stomach Small Intestine Large Intestine Rectum Slide 5 Accessory Organs Salivary Glands Tongue Pancreas Liver Gallbladder An organ that helps with digestion but is not part of the digestive tract. These organelles add secretions to the digestive system Slide 6 The Mouth Teeth physically break apart food The process of chewing begins the early stages of mechanical digestion Digestive enzymes released from salivary glands begin breaking down carbohydrates into smaller molecules (chemical digestion) Slide 7 Saliva Helps to moisten food Makes food easier to chew The amount of saliva released is controlled by the nervous system You often produce saliva in the presence of the smell of food Saliva contains salivary amylase, an enzyme that breaks the bonds of starches into sugar (glucose) Slide 8 Esophagus Esophagus is most commonly referred to as the food pipe It connects the throat (pharynx) to the stomach Once the food is chewed and becomes a clump it is referred to as the bolus The bolus is propelled down the throat via peristalsis Slide 9 Peristalsis Peristalsis is the contraction of the throat that moves the bolus downwards towards the stomach Slide 10 Epiglottis The epiglottis is a flap of connective tissue that separates the trachea away from the esophagus Slide 11 Stomach The esophagus empties the bolus into the stomach Large muscular sack that continues mechanical and chemical digestion The three layers that churn and mix food with mucus and gastic juice secreted from the lining of the interior of the stomach Extremely acidic with a pH of 1 Mucus functions to protect the interior lining of the stomach from itself Slide 12 Stomach Cont High acidity activates pepsin an enzyme that begins the digestion of protein Because enzymes that break down carbohydrates cannot function in high acidity they no longer break down carbohydrates in the stomach Chyme is what is produced by the stomach Chyme travels from the stomach through the pyloric valve into the small intestines Slide 13 The Small Intestines Small intestines is made up of three parts, the duodenum, the jejunum and the ileum 6-7 meters long Secretes peptidase that breaks dipeptides into amino acids Secretes other enzymes that break down disaccharides into monosaccharides Slide 14 The Pancreas Does not directly participate in digestion A gland that secretes the enzymes amylase, trypsin, and lipase into the small intestines Amylase breaks down carbohydrates Trypsin breaks down proteins Lipase breaks down lipids Slide 15 Liver Aids the pancreas Has right and left lobe Produces bile, a fluid that consists of lipids and salts. Bile dissolves and disperses fat droplets found in fatty foods Bile is stored in the gallbladder Slide 16 Slide 17 Absorption in Small Intestines Villi are fingerlike projections that line the surface of the small intestine They are adapted for the absorption of nutrients Villi are covered in more projections called microvilli The increased amount of surface area allows for rapid absorption of nutrients By the time the food is leaving the small intestines it has been depleted of all its nutrients Slide 18 Slide 19 Large Intestines Also known as the colon Functions to remove water from undigested material Water is absorbed quickly across the wall of the large intestines The concentrated waste that remains once water has been removed is excreted out of the body through the rectum