1. The Digestive System and Nutrients
Elli Kim, Vanessa Tam, Penny Ryu

2. Parts of the Digestive System
Digestive tract organs
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
Accessory organs
Salivary glands
Liver
Gallbladder
Pancreas

3. Digestive Tract Organs
Mouth – teeth chew food; tongue tastes and pushes food for chewing and swallowing
Pharynx – passageway where food is swallowed
Esophagus – passageway where peristalsis pushes food to stomach
Stomach – secretes acid and digestive enzyme for protein; churns, mixing food with secretions, and sends chyme to small intestine

4. Pharynx

5. Digestive Tract Organs (Cont.)
Small intestine – mixes chyme with digestive enzymes for final breakdown; absorbs nutrient molecules into body; secretes digestive hormones into blood
Large intestine – absorbs water and salt to form feces
Rectum – stores and regulates elimination of feces
Anus – you know what it is

6. Accessory Organs
Salivary glands – secrete saliva; contains digestive enzyme for carbohydrates
Liver – major metabolic organ: processes and stores nutrients; produces bile for emulsification of fats
Gallbladder – stores bile from liver; sends it to the small intestine
Pancreas – produces pancreatic juice: contains digestive enzymes, and send it to the small intestine; produces insulin and secretes it into the blood after eating

8. When the food gets eaten…

9. The Process of Digestion
Mouth: breaks down food
Teeth chew the food to break it down to smaller pieces
Saliva is produced by the salivary glands
Saliva contains an enzyme (salivary amylase) that begins to digest the starch from food into smaller molecules
Pharynx: throat swallows food (voluntary)
Esophagus: squeezes the food down (involuntary)
Layer of muscle enables walls to move
Propels food and liquid through the system
Mix the contents
Compare with squeezing mentos
Arrives at the Lower Esophageal Sphincter

10. The Process of Digestion
Lower Esophageal Sphincter: ring-like organ that closes the passage between two organs
 As food approaches the sphincter, it relaxes so that the food can pass through
Peristalsis: food moves from one organ to the next
Stomach: excretes stomach acid to break food down
 Thick mucus layer (pepsinogen): protects the interior stomach walls to prevent stomach acid from dissolving stomach tissues (or else: peptic ulcer)
Produces stomach acid (gastric juice: digestive enzymes + HCl; regulated by gastrin) and a protein-digestive enzyme
Stores food and liquid: upper stomach muscles relaxes and absorbs food
Lower stomach mixes: mixes food, liquid, and digestive juice made by the stomach to make chyme
Push materials into small intestines through the pyloric sphincter

11. The Process of Digestion
Small Intestines: digest and absorb
Duodenum: (1st 25 cm) digests starch (pancreatic amylase), protein (proteolytic), fat (lipase) , nucleotides (phosphatases), disaccharides (maltase, lactase)
- Mix digestive juice produced by:
Pancreas: enzymes that break down carbohydrates, fats, and proteins (trypsin, chymotrypsin, lipase, pancreatic amylase); stimulated by secretin (produced by duodenim)
Liver: bile (squeezed out from the gallbladder through bile ducts) dissolves fat into liquid; stimulated by cholecystokinin (produced by small intestines)
Interior glands of the small intestines
Jejunum (first part), Ileum (second part)
Villi and Microvilli: large surface area allows better absorption into capillaries

12. The Process of Digestion
Large Intestines (colon): absorbs water and produce feces
Cecum: appendix is attached at the end (tail-like)
Ascending colon: food going
Trasverse Colon: food is going horizontal
Descending colon: food going down
Sigmoid Colong
Concentrates waste materials
Pushes the waste through rectum to anus
Anus: waste is excreted

14. Problem with the Stomach and the Intestine
Diarrhea:
contents of the intestines move too fast  isn't enough time for water to be absorbed before the feces are pushed out of the body
Constipation:
contents of the large intestines do not move along fast enough  waste materials stay in the large intestine so long  too much water is removed and the feces become hard.

15. Nutrients Protein-------amino acids Starch------simple sugars
Fats------fatty acids & glycerol
Vitamins
Minerals

16. Proteins Ex./ meat, eggs, beans
enzymes from the pancreatic juice and the lining of the intestine carry out the breakdown of big molecules into small molecules
absorbed from hollow of the small intestines into the blood and into the rest of the body

17. Carbohydrates
-Ex./ bread, potatoes, pastries, rice, fruits, table sugar
(many of these contain both starch & fiber)
Digestible carbohydrates are broken down by enzymes in the saliva
Starch is digested in 2 steps…
1) enzyme in the saliva & pancreatic juice breaks the starch into maltose then maltase splits the maltose into glucose molecules
2) glucose is carried to the liver

18. Fats dissolved into watery content of the intestinal cavity
bile acids (produced by liver) are natural detergents to dissolve fat into water, allowing the enzymes to break large fat molecules into smaller molecules (fatty acids & cholesterol)
bile acids help fatty acids and cholesterol to move into mucosa
In mucosa, small molecules are formed back into big molecules  theses molecules pass into lymphatic vessels near the intestine  these vessels carry these fats to the veins blood carries these to different parts of the body