Human Digestion -Ch. 35.1 Section Objectives: Interpret the different functions of the digestive system organs. Outline th...
Human Digestion <ul><li>This part of the life process of  NUTRITION->  process by which an organism obtains and utilizes f...
Overview: Food processing occurs in four stages <ul><li>Ingestion : taking in food </li></ul><ul><li>Digestion : mechanica...
Human Digestion~  a 2 part process that changes food into a form useable by the body cells <ul><li>1.  Mechanical digestio...
Examples of chemical Digestion : <ul><li>1. Carbohydrates+ water -> simple sugars (glucose for instance) </li></ul><ul><li...
HUMAN DIGESTIVE SYSTEM <ul><li>Human digestive tract = GI ( gastrointestinal ) Consists of a continuous one way food tube ...
HUMAN DIGESTIVE SYSTEM <ul><li>1 . Mouth : (oral cavity) ingests food </li></ul><ul><li>2.  Teeth : function in mechanical...
HUMAN DIGESTIVE SYSTEM <ul><li>Salivary glands  are located in the mouth </li></ul><ul><ul><li>Produce and secrete salivar...
HUMAN DIGESTIVE SYSTEM <ul><li>4.  Pharynx : food is pushed by tongue to back of throat, initiates swallowing – food is no...
HUMAN DIGESTIVE SYSTEM <ul><li>6 . Stomach : J-shaped, sac-like , muscular organ that mechanically churns food into a liqu...
HUMAN DIGESTIVE SYSTEM <ul><li>Components of gastric juice: </li></ul><ul><ul><li>1. water-solvent </li></ul></ul><ul><ul>...
HUMAN DIGESTIVE SYSTEM <ul><li>7.  Small Intestine : the major organ of chemical digestion and nutrient absorption, long t...
Absorption <ul><li>7.  Small intestine : besides digestion being  completed in the small intestine, its other main functio...
Accessory organs <ul><li>1.  Pancreas : located near small intestine </li></ul><ul><ul><li>Produces juices, enzymes, and f...
Accessory organs <ul><li>2 . Liver : largest internal organ ( has many functions outside digestion) </li></ul><ul><ul><li>...
HUMAN DIGESTIVE SYSTEM <ul><li>8 . Large Intestine :  primarily a drying and storage organ. </li></ul><ul><ul><li>undigest...
Some   Digestive Homeostasis Disorders <ul><li>1.Constipation – person has uncomfortable or infrequent bowel movements res...
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Human digestion _ch[1]._35

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Human digestion _ch[1]._35

  1. 1. Human Digestion -Ch. 35.1 Section Objectives: Interpret the different functions of the digestive system organs. Outline the pathway food follows through the digestive tract. Identify the role of enzymes in chemical digestion .
  2. 2. Human Digestion <ul><li>This part of the life process of NUTRITION-> process by which an organism obtains and utilizes food </li></ul>
  3. 3. Overview: Food processing occurs in four stages <ul><li>Ingestion : taking in food </li></ul><ul><li>Digestion : mechanical and chemical breakdown of food so that it can be absorbed by the cells </li></ul><ul><li>Absorption : cells lining the digestive tract take up (absorb) small nutrient molecules </li></ul><ul><li>Elimination : undigested material passes out of the digestive tract </li></ul>
  4. 4. Human Digestion~ a 2 part process that changes food into a form useable by the body cells <ul><li>1. Mechanical digestion – physical breakdown of large pieces of food into smaller ones </li></ul><ul><li>2. Chemical digestion – hydrolysis – the splitting of large insoluble molecules in small, soluble molecules with the use of water and enzymes ( in other words; breaking complex molecules into simple ones) </li></ul><ul><li>The process of chemical digestion ( hydrolysis ) is regulated by enzymes </li></ul>
  5. 5. Examples of chemical Digestion : <ul><li>1. Carbohydrates+ water -> simple sugars (glucose for instance) </li></ul><ul><li>2. Proteins+ water -> amino acids </li></ul><ul><li>3. Lipids+ water -> 3 fatty acids +gylcerol </li></ul>
  6. 6. HUMAN DIGESTIVE SYSTEM <ul><li>Human digestive tract = GI ( gastrointestinal ) Consists of a continuous one way food tube ( mouth to anus) </li></ul>
  7. 7. HUMAN DIGESTIVE SYSTEM <ul><li>1 . Mouth : (oral cavity) ingests food </li></ul><ul><li>2. Teeth : function in mechanical breakdown of food, increases surface area of food for enzyme action </li></ul><ul><li>3. Tongue : acts as a plunger to push food back into the throat ( pharynx ) taste buds are located on the surface of the tongue </li></ul>
  8. 8. HUMAN DIGESTIVE SYSTEM <ul><li>Salivary glands are located in the mouth </li></ul><ul><ul><li>Produce and secrete salivary amylase which starts the chemical digestion of starch </li></ul></ul><ul><ul><li>Provides lubrication for the chewed food </li></ul></ul><ul><ul><li>Contains enzymes to kill harmful microbes </li></ul></ul>
  9. 9. HUMAN DIGESTIVE SYSTEM <ul><li>4. Pharynx : food is pushed by tongue to back of throat, initiates swallowing – food is now in the form of a bolus </li></ul><ul><ul><li>Epiglottis : flap that prevents choking </li></ul></ul><ul><li>5 . Esophagus : muscular tube that moves food from mouth to the stomach by process of peristalsis : wave of muscular contractions that moves chewed food to stomach </li></ul>
  10. 10. HUMAN DIGESTIVE SYSTEM <ul><li>6 . Stomach : J-shaped, sac-like , muscular organ that mechanically churns food into a liquid and begins chemical digestion of protein, lining secretes gastric juice, stomach empties in about 2-6hrs., food now liquid called chyme </li></ul>
  11. 11. HUMAN DIGESTIVE SYSTEM <ul><li>Components of gastric juice: </li></ul><ul><ul><li>1. water-solvent </li></ul></ul><ul><ul><li>2. mucus-lubrication </li></ul></ul><ul><ul><li>3. pepsin- protease enzyme that begins chemical digestion of protein </li></ul></ul><ul><ul><li>4. hydrochloric acid (HCl) ph=2,activates pepsin </li></ul></ul>
  12. 12. HUMAN DIGESTIVE SYSTEM <ul><li>7. Small Intestine : the major organ of chemical digestion and nutrient absorption, long twisted tube with small diameter, </li></ul><ul><li>enzymes and fluids needed to complete chemical digestion come 3 separate sources: </li></ul><ul><ul><li>1. intestine itself </li></ul></ul><ul><ul><li>2. pancreas-. Small intestine </li></ul></ul><ul><ul><li>3. liver-> gallbladder->small intestine </li></ul></ul>
  13. 13. Absorption <ul><li>7. Small intestine : besides digestion being completed in the small intestine, its other main function is absorption of the digested molecules into the blood </li></ul><ul><li>Villi : fingerlike projections that increase surface area of small intestine contain a network of capillaries for absorption of amino acids and simple sugars into blood, center contains lymph vessel called lacteal which absorbs fatty acids </li></ul>
  14. 14. Accessory organs <ul><li>1. Pancreas : located near small intestine </li></ul><ul><ul><li>Produces juices, enzymes, and fluids </li></ul></ul><ul><ul><li>Produces sodium bicarbonate that neutralizes HCl acid from stomach </li></ul></ul><ul><ul><li>Works best at neutral pH </li></ul></ul>
  15. 15. Accessory organs <ul><li>2 . Liver : largest internal organ ( has many functions outside digestion) </li></ul><ul><ul><li>Makes bile ~ bile NOT an enzyme,) bile emulsifies lipids- breaks them into smaller droplets to increase the surface area for enzymes (lipases) to act on fats </li></ul></ul><ul><li>3. Gallbladder : small storage sac for bile, carries bile to small intestine </li></ul>
  16. 16. HUMAN DIGESTIVE SYSTEM <ul><li>8 . Large Intestine : primarily a drying and storage organ. </li></ul><ul><ul><li>undigested and unabsorbed material pass into LI through sphincter muscle </li></ul></ul><ul><ul><li>No digestion occurs in LI </li></ul></ul><ul><ul><li>Functions: </li></ul></ul><ul><ul><ul><li>1. reabsorption of water and salts </li></ul></ul></ul><ul><ul><ul><li>2. absorption of vitamins produced by bacteria that live in the LI </li></ul></ul></ul><ul><ul><ul><li>3. storage and elimination of fecal matter </li></ul></ul></ul><ul><li>9. Rectum: last part of the digestive system: feces are eliminated through the anus </li></ul>Large intestine (colon) Small intestine Rectum Anus End of small intestine Nutrient flow
  17. 17. Some Digestive Homeostasis Disorders <ul><li>1.Constipation – person has uncomfortable or infrequent bowel movements results from sluggish peristalsis that allows excess water to be removed from feces (fecal matter hardens)- may result from insufficient fiber in diet </li></ul><ul><li>2 . Diarrhea – opposite of constipation– associated with intestinal disturbances caused by infections or stress– prolonged diarrhea may result in severe dehydration </li></ul><ul><li>3. Gall stones – small hard particles made of cholesterol which form & collect in gall bladder- may block the bile duct and cause pain </li></ul><ul><li>4. acid reflux -backflow of stomach contents upward into esophagus </li></ul><ul><li>5. appendicitis - inflammation of appendix </li></ul>

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