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Digestive System

Digestive System. Function. The mechanical/chemical breakdown of foods and absorption of nutrients by cells A limentary canal (9m from mouth to anus) A ccessory organs- pancreas, liver, gall bladder. Alimentary Canal.

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Digestive System

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  1. Digestive System

  2. Function • The mechanical/chemical breakdown of foods and absorption of nutrients by cells • Alimentary canal (9m from mouth to anus) • Accessory organs- pancreas, liver, gall bladder

  3. Alimentary Canal • mouth, pharynx, esophagus, stomach, sm intestine, lg intestine, anal canal • Movements of Tube: • Mixing movements- rhythmic contractions that mix food with digestive juices • Propelling movements- rings of muscles contract/relax to push food down canal (Peristalsis)

  4. Mouth • Begins digesting by chewing/mixing food with saliva • Tongue- moves food • connect to floor of mouth by frenulum • taste buds

  5. Palate- forms roof of oral cavity • Uvula at back of mouth • Palatine tonsils- back of mouth/throat • Organs protect against infection • Teeth- primary vs. secondary • Incisors, cuspids, bicuspids, premolars, molars • Used for chewing food

  6. Salivary GLands • Serous cells produce amylase- breakdowns food • Mucous cells produce mucus- lubrication during swallowing • Parotid Glands • Submandibular Glands • Sublingual Glands

  7. Pharynx/Esophagus • Pharynx- nasal and oral cavities • nasopharynx,oropharynx, laryngopharynx • Esophagus- moves to the stomach, penetrates the diaphragm at the esophageal hiatus • lower esophageal sphincter-prevent food and chemicals from moving up the stomach

  8. Stomach • *J-shaped, pouch like organs that hangs inferior to the diaphragm • 1 liter capacity • Four main parts of the stomach • Cardiac -esophageal opening-cardiac sphincter • Fundic -temporary storage area, lies above the cardiac region • Body -central area of the stomach • Pyloric -pyloric sphincter, controls emptying of the stomach into the sm. Intestine

  9. Rugae – folds within the stomach, increase surface area

  10. Lining of the stomach is a mucous membrane – with small openings called gastric pits, containing gastric glands • Gastric Juice- pepsin Chyme–broken down food molecules from gastric juices/movement of stomach • released from the pyloric sphincter valve into the first portion of the small intestine – duodenum

  11. Pancrease • secretes pancreatic juicePancreatic juice – digests fats, breaks down nucleic acids into nucleotides

  12. Liver • BILIARY SYSTEM – functions to create bile used in digestion; liver, gall bladder and ducts • LIVER- large right lobe and small left lobe • Hepatic portal vein – delivers blood to the liver

  13. Functions • maintains normal concentration of blood glucose • breakdown of lipids and fats • protein metabolism (forming urea, synthesizing plasma proteins such as clotting factors,(converting amino acids); • stores iron and vitamins • destroys damaged red blood cells • removes toxic substances from the blood • secretes bile

  14. Bile – yellowish-green liquid secreted from hepatic cells (when bile pigments build up in blood, skin turns green, a condition called jaundice). • Bile empties into the duodenum • Bile aids in digestion, bile salts break down fat globules into smaller droplets – emulsification

  15. Gall Bladder- stores bile

  16. Small Intestine • tubular organ that extends from the pyloric sphincter, many loops and coils, fills much of the abdominal cavity • receives secretions from the pancreas and liver, completes digestion of nutrients and chyme, absorbs 1. Duodenum - first part of the small intestine2. Jejunum – second part, ~2.2 m3. Ilium – third part, longest ~3.3 m • *jejunum and ilium are continuous

  17. Intestinal Villi – increase surface area for absorption • Function- secrete chemicals to break down food and carry away these nutrients in the blood (absorption)

  18. Large Intestine • Cecum– beginning of the large intestine, pouchlike, closed end called the vermiform appendix (ileocecalvalve) • Colon – ascending / transverse / descending / sigmoid • Rectum – stores waste before it is expelled from the body • Anal canal - ends in the anus, muscular sphincter which controls the exit of waste

  19. Functions – secretes mucus to protect the wall against abrasion - reabsorbs water and passes along material that was not digested - contains intestinal flora (bacteria to break down cellulose, also produce intestinal gas) • Mass movements – large portions of the colon contract to move material through it, 2-3 times a day usually after eating

  20. Sum it up 1. Food  2. Mouth-teeth, tongue, amylase break down 3. Moves down Esophagus by Peristalsis 4. Enters stomach- chyme 5. Enters Sm. Intestine at Deudenum- liver/gall bladder secret bile – villi absorb nutrients  jejunum  ileum 6. Enters Lg. Intestine Cecum Colon Rectum Anus

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