Ch 14 B Accessory Organs

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Ch 14 B Accessory Organs

  1. 1. Chapter 14 B: Digestive – Accessory Organs
  2. 2. Accessory Digestive Organs <ul><li>Salivary glands </li></ul><ul><li>Teeth </li></ul><ul><li>Pancreas </li></ul><ul><li>Liver </li></ul><ul><li>Gall Bladder </li></ul>
  3. 3. <ul><li>1. Salivary Glands </li></ul><ul><li>3 glands </li></ul><ul><ul><li>- Parotid glands – located anterior to ears </li></ul></ul><ul><ul><li>- Submandibular glands </li></ul></ul><ul><ul><li>- Sublingual glands </li></ul></ul><ul><li>Saliva </li></ul><ul><ul><li>Mostly water </li></ul></ul><ul><ul><li>Helps to form a food bolus </li></ul></ul><ul><ul><li>salivary amylase to begin starch digestion </li></ul></ul><ul><ul><li>Dissolves chemicals so they can be tasted </li></ul></ul>
  4. 4. <ul><li>2. Teeth - Masticates (chews) food </li></ul><ul><ul><li>- Deciduous (baby or milk) teeth; 20 teeth by age two </li></ul></ul><ul><ul><li>- Permanent teeth; between the ages of 6 to 12; full set = 32 teeth </li></ul></ul>
  5. 5. <ul><li>Regions of a Tooth </li></ul><ul><li>Crown – exposed part </li></ul><ul><li>Outer enamel </li></ul><ul><li>Neck </li></ul><ul><li>Region in contact with the gum </li></ul><ul><li>Connects crown to root </li></ul><ul><li>Root </li></ul><ul><li>Root canal carrying blood vessels and nerves </li></ul>
  6. 6. <ul><li>3. Pancreas </li></ul><ul><li>Makes many digestive enzymes that break down all categories of food </li></ul><ul><li>Enzymes secreted into duodenum </li></ul><ul><li>Alkaline fluid introduced with enzymes neutralizes acidic chyme </li></ul><ul><li>Endocrine products of pancreas </li></ul><ul><ul><li>Insulin </li></ul></ul><ul><ul><li>Glucagons </li></ul></ul>
  7. 7. <ul><li>4. Liver & Bile </li></ul><ul><li>Largest gland; right side under the diaphragm </li></ul><ul><li>4 lobes suspended by the falciform ligament </li></ul><ul><li>Connected to the gall bladder via the common hepatic duct </li></ul><ul><li>Bile made by cells in the liver </li></ul><ul><li>Bile composition </li></ul><ul><ul><li>Bile salts </li></ul></ul><ul><ul><li>Bile pigment (bilirubin - breakdown of hemoglobin) </li></ul></ul><ul><ul><li>Cholesterol </li></ul></ul><ul><ul><li>Phospholipids </li></ul></ul><ul><ul><li>Electrolytes </li></ul></ul>
  8. 8. <ul><li>5. Gall Bladder </li></ul><ul><li>Sac found in hollow fossa of liver </li></ul><ul><li>Stores bile from the liver by way of the cystic duct </li></ul><ul><li>Bile is introduced into the duodenum in the presence of fatty food </li></ul><ul><li>Gallstones can cause blockages </li></ul>
  9. 9. <ul><li>Processes of the Digestive System </li></ul>1 . Ingestion –into mouth 2. Propulsion – moving foods 3. Mechanical digestion - Mixing food a. mouth & tongue b. stomach churning c. segmentation in sm. int. 4. Chemical Digestion - Enzymes break down food 5. Absorption - products into the blood or lymph 6. Defecation - Elimination of indigestible substances as feces
  10. 10. <ul><li>Control of Digestive Activity </li></ul><ul><li>Controlled by reflexes via the parasympathetic division </li></ul><ul><li>Chemical & mechanical receptors are located in organ walls that trigger reflexes </li></ul><ul><li>Stimuli include: </li></ul><ul><ul><li>Stretch of the organ </li></ul></ul><ul><ul><li>pH of the contents </li></ul></ul><ul><ul><li>Presence of breakdown products </li></ul></ul><ul><li>Reflexes include: </li></ul><ul><ul><li>Activation or inhibition of glandular secretions </li></ul></ul><ul><ul><li>Smooth muscle activity </li></ul></ul>
  11. 11. <ul><li>Food Breakdown in the Stomach </li></ul><ul><li>Gastric juice - regulated by nerves & hormones </li></ul><ul><li>Presence of food or falling pH = release of gastrin </li></ul><ul><li>Gastrin causes stomach glands to produce protein-digesting enzymes </li></ul><ul><li>Hydrocholoric acid makes stomach very acidic </li></ul><ul><ul><li>Activates pepsinogen to pepsin for protein digestion </li></ul></ul><ul><ul><li>Provides a hostile environment for microorganisms </li></ul></ul>
  12. 12. <ul><li>Digestion and Absorption </li></ul><ul><li>Protein digestion enzymes </li></ul><ul><ul><li>Pepsin – an active protein digesting enzyme </li></ul></ul><ul><ul><li>Rennin – works on digesting milk protein </li></ul></ul><ul><li>The only absorption that occurs in the stomach is of alcohol and aspirin </li></ul><ul><li>Stomach empties in 4-6 hrs. </li></ul>
  13. 13. <ul><li>Digestion in the Small Intestine </li></ul><ul><li>Enzymes from the brush border </li></ul><ul><ul><li>Break double sugars into simple sugars </li></ul></ul><ul><ul><li>Complete some protein digestion </li></ul></ul><ul><li>Pancreatic enzymes </li></ul><ul><ul><li>Help complete digestion of starch (pancreatic amylase) </li></ul></ul><ul><ul><li>Carry out about half of all protein digestion (trypsin, etc.) </li></ul></ul><ul><ul><li>Responsible for fat digestion (lipase) </li></ul></ul><ul><ul><li>Digest nucleic acids (nucleases) </li></ul></ul><ul><ul><li>Alkaline content neutralizes acidic chyme </li></ul></ul>
  14. 14. <ul><li>Stimulation of Pancreatic Juice </li></ul><ul><li>Chyme enters duodenum and causes mucuosal cells to release secretin and cholecystokinin </li></ul><ul><li>CCK enters the bloodstream </li></ul>
  15. 15. <ul><li>CCK reaches the pancreas and causes the pancreas to release enzyme rich pancreatic juice </li></ul><ul><li>Secretin causes secretion of bicarbonate rich pancreatic juice </li></ul>
  16. 16. <ul><li>Absorption in the Small Intestine </li></ul><ul><li>Water is absorbed along the length of the small intestine </li></ul><ul><li>End products of digestion </li></ul><ul><ul><li>Most substances are absorbed by active transport through cell membranes </li></ul></ul><ul><ul><li>Lipids are absorbed by diffusion </li></ul></ul><ul><li>Substances are transported to the liver by the hepatic portal vein or lymph </li></ul>
  17. 17. <ul><li>Absorption in the Large Intestine </li></ul><ul><li>No digestive enzymes are produced </li></ul><ul><li>Resident bacteria digest remaining nutrients </li></ul><ul><ul><li>Produce some vitamin K and B </li></ul></ul><ul><ul><li>Release gases </li></ul></ul><ul><li>Water and vitamins K and B are absorbed </li></ul><ul><li>Remaining materials are eliminated via feces </li></ul>
  18. 18. <ul><li>Propulsion in the Large Intestine </li></ul><ul><li>Sluggish peristalsis </li></ul><ul><li>Mass movements </li></ul><ul><ul><li>Slow, powerful movements </li></ul></ul><ul><ul><li>Occur three to four times per day </li></ul></ul><ul><li>Presence of feces in the rectum causes a defecation reflex </li></ul><ul><ul><li>Internal anal sphincter is relaxed </li></ul></ul><ul><ul><li>Defecation occurs with relaxation of the voluntary (external) anal sphincter </li></ul></ul>

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