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The Digestive System.

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Presentation on theme: "The Digestive System."— Presentation transcript:

1 The Digestive System

2 Nutrients Nutrients: substances in food that supply energy and raw materials for growth, repair, and maintenance Nutrients needed by body are: water, carbohydrates, fats, proteins, vitamins, and minerals

3 Water Most important nutrient
many body processes & chem rxns take place in water Composes most body fluids

4 Carbohydrates main energy source
Sugars broken down by digestive system and placed in blood stream Sugars are stored in tissue to create ATP

5 Fats Mainly used for cell membranes Insulation and protection
Also used for hormones and myelin sheaths

6 Proteins Raw materials for growth and repair structures
Skin and muscle Hormones and enzymes Insulin hemoglobin

7 Vitamins Vitamins: organic molecules that regulate body processes
Work with enzymes From our food; We cannot make them (except vitamin D)

8 Minerals Minerals: inorganic nutrients needed in small amounts
Calcium: bones Iron: hemoglobin

9 Gastrointestinal tract: long, winding tube which begins with the mouth and ends with the anus
Digestion: process of breaking down food into molecules the body can use

10 Mechanical Digestion Teeth tear food into smaller pieces
Tongue and palate form a small ball of food called a bolus Esophagus moves food to stomach by a series of wavelike contractions called peristalsis Stomach mixes and churns the food

11 Chemical Digestion Salivary amylase in saliva starts to break down starch into smaller sugars (glucose) Pepsin in stomach starts to break down proteins- * Reason why diabetics have to inject insulin. If taken by mouth the peptide hormone insulin will be broken down into smaller subunits of proteins called amino acids.

12 Esophagus 10 inch tube that connects the pharynx with stomach
Located between trachea and spine Peristalsis moves food from pharynx to stomach Mucus is secreted in lining to moisten and aid in movement of food


14 Stomach Located between the esophagus and the small intestines
sphincters at each end control movement of material in and out Contains pepsin Contains HCL(hydrochloric acid); acidic environment aids digestion Lining secretes mucus to protect stomach wall against being burned by HCL



17 Ulcer


19 Liver- Accessory Organ of Digestive System
Produces bile - emulsifies fat to help digestion by enzymes Also filter blood of harmful and toxic substances like alcohol, and drugs


21 Gall Bladder-Accessory Organ
Stores bile After eating a meal the gall bladder will contract and squirt bile into small intestine.

22 Pancreas – accessory organ
Helps neutralize stomach acid Pancreatic enzymes digest carbs, lipids, proteins, and nucleic acids

23 Small Intestines Located between the stomach and the large intestines
About 23 ft. long About 1 inch in diameter Site of absorption of nutrients Contain villi and microvilli-fingerlike extensions that increase surface area Chemical digestion of lipids, proteins and carbohydrates Receives bile from gall bladder/liver, and enzymes from the pancreas



26 Villi (Villus sing.)

27 Large Intestines absorption of water from undigested material occurs
Bacteria present which aid in production of vitamin K Taking antibiotics can cause a vitamin K deficiency


29 Appendix

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