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Download Digestive System - Effingham County Schools
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The Digestive System 1 Major Functions • Digestion- Break down food into the nutrients the body can absorb. • Absorption- Take out nutrients out of the food we eat and deliver it to the cells in our body. • Eliminate solid wastes that is not needed by the body. 2 Digestion • Processing of food • Types – Mechanical (physical) • • • • • Chew Tear Grind Mash Mix Examples of Mechanical Digestion – Chemical- uses catabolic reactions and enzymes to break down food • Saliva • Stomach Acids • Bile used to break down fats 3 Digestion • Phases – – – – – Ingestion Movement Digestion Absorption Further digestion 4 Digestive System Organization • Gastrointestinal (Gl) tract – Tube within a tube – Direct link/path between organs – Major Organs: MouthPharynx Esophagus Stomach Small Intestines Large Intestines Rectum 5 Digestive System Organization • Accessory Organs – Not in tube path – Organs • • • • • • Teeth Tongue Salivary glands Liver Gall bladder Pancreas 6 Mouth- where digestion begins Teeth- Mechanical Digestion Salivary Glands- Chemical digestion of compounds such as starch 7 Teeth- Mechanical Digestion 8 Surface of the Tongue 9 The Major Salivary Glands 10 __________________ Peristalsis Deglutition (swallowing) • Sequence – A. Voluntary stage • Push food to back of mouth – B. Pharyngeal stage • Raise pallate - C. Esophageal stage- Contract pharyngeal muscles, open esophagus, start peristalsis 11 Esophagus • Usually collapsed (closed) • Functions – Secrete mucous – Transport food to the stomach 12 Peristalsis Contractions of smooth muscles that push food down the digestive tract 13 Esophagus • Sphincters – Upper – Lower • Abnormalities – – – – – Achalasia Atresia Hernia Barret’s esophagus Esophageal varices 14 Stomach • Usually “J” shaped • Mucous membrane – G cells – make gastrin – Goblet cells – make mucous – Gastric pit – Oxyntic gland – Parietal cells – Make HCl – Chief cells – Zymogenic cells • Pepsin • Gastric lipase Very Acidic, but the cells are produced faster than they die 15 Anatomy of the Stomach 16 Stomach • Functions 1. Mix food- Mechanically 2. Reservoir- Store food 3. Start chemical digestion of • Protein • Nucleic acids • Fats 5. Absorbs • • • • Alcohol Water Lipophilic acid B 12 4. Destroy some bacteria 17 Stomach Function- To mix, break down (chemically and mechanically), and store food. • Inner surface thrown into folds – Rugae • Contains enzymes that work best at pH 1-2 (VERY ACIDIC) 18 Stomach • Food leaves the stomach as a soupy mixture called chyme 19 Small Intestine • Function- Major site of chemical digestion and absorption. • Movements – Peristalsis • Absorbs – – – – – 80% ingested water Vitamins Minerals Carbonates Proteins 20 Structure of the Villi in the Small Intestine Villi- Increase surface area for absorption. 21 Small Intestine- Accessory Organs • Liver- Creates bile that is used to break down fats. • Gal bladder- Stores bile and releases it into the small intestines • Pancreas- Creates pancreatic juices that neutralize the chyme. 22 23 Anatomy of the Large Intestine 24 Large Intestine Function- To reabsorb water from digested wastes to make solid wastes. - No villi – No permanent circular folds – Smooth muscle •Chyme dehydrated to form feces 25 Feces Formation and Defecation “whats in it?” • Chyme dehydrated to form feces • Feces composition – – – – – Water Inorganic salts Epithelial cells Bacteria Byproducts of digestion Defecation – Peristalsis pushes feces into rectum – Rectal walls stretch until full 26 Anatomy of the Large Intestine 27 The Organs and Positions in the Abdominal Cavity 28 Video of the digestion of food- The whole picture http://highered.mcgrawhill.com/sites/0072495855/stude nt_view0/chapter26/animation__ organs_of_digestion.html 29 Digestive Disorders Chrone’s Disease (inflammatory bowel syndrome)Inflammation of the intestines 30 Digestive disorders Blind loop syndromeDiarrhea- increased Blind loop syndrome frequency of watery occurs when part of the feces. Causing intestine becomes dehydration and bypassed, so that digested food slows or stops moving abdominal pain. through the intestines. This causes bacteria to grow too much in the intestines and leads to problems in absorbing nutrients. 31 Digestive Disorders Phenylketonuria (PKU)- is a rare condition in which a baby is born without the ability to properly break down an essential amino acid called phenylalanine. 32 Symptoms •Lighter skin and hair color •Delayed mental and social skills •Bad breath and odor from skin and urine. 33 PKU is a recessive trait and therefore both parents must carry the allele to pass the trait. 34 Mouth Salivary gland Esophagus Liver Gal Bladder Small Intestines Stomach Pancreas Large Intestines Rectum Anus 35
