1. Digestive

2. Function Break down food into molecules to obtain energy that the body needs: (ATP) 4 steps involved: 1. Ingestion- take food in 2. Digestion- break down food 3. Absorption- keep molecules body needs 4. Elimination- get rid of waste

3. Digestion can occur in 2 ways Mechanical- physical break down of the food- occurs in the mouth using your teeth and also in the stomach due to churning. Purpose -- increase the surface area so more sites are available for the enzymes to act upon. Chemical- enzymes break the bonds in the food. This occurs in the mouth, stomach and small intestine.

4. Food Pathways We will follow the path of food beginning in the mouth until it reaches the point of elimination. Mouth Pharynx Epiglottis Esophagus Stomach Small intestine Pancreas http://www.youtube.com/ watch?v=Z7xKYNz9AS0 Liver Gallbladder Large Intestine Rectum

5. Mouth Site of mechanical digestion. Teeth break food into smaller pieces to increase surface area for the enzymes to work. Have different teeth for different food types. Salivary glands release saliva to mix with food. Contains SALIVARY AMYLASE- enzyme which breaks down carbohydrates. Saliva also acts as lubricant to help food go down the esophagus. Act of chewing and tongue form food into BOLUS before it is swallowed.

6. Swallowing When food is swallowed a small flap of tissue called the EPIGLOTTIS covers the trachea (air pipe which leads to lungs) so food goes down the correct tube. Esophagus-Muscle(smooth) covered tube that connects mouth to the stomach Food is moved down the esophagus by waves of muscle contraction called PERISTALSIS

7. The Mouth and Pharynx

8. Peristalsis http://health.howstuffworks.com/adam-200088.htm http://health.howstuffworks.com/adam-200088.htm

9. Stomach Muscular pouch Mechanical digestion- churning Chemical digestion-pepsin digests proteins Other gastric juices and HCl (pH of 2) digest the food (break the bonds between the molecules) and turns food into a soupy liquid called CHYME Sphincter- acts as valves to let food into stomach Stomach is covered in thick mucous to prevent HCL damage. Takes 2-4 hrs for food to leave the stomach

10. Esophagus and Stomach

11. The Small Intestine 6 meters long Pyloric valve-valve between stomach and small intestines Made of 3 sections: Duodenum,Jejunum, and Ileum Main site of absorption Pancreas-adds sodium bicarbonate (NAHCO3) to balance PH Additional enzymes added here from small intestine, pancreas, liver and gall bladder

12. Small intestine

13. Structure of small intestine The Small Intestine isn’t a smooth tube- it has little finger like projections called villi and micro villi that help increase the surface area of the small intestine that allow for increased absorption.

15. The Accessory Organs Liver and Gall Bladder Pancreas Liver produces BILE Bile helps digest fat by surrounding the fat droplets so they break into smaller particles. (Emulsification) Gall Bladder stores bile and delivers it when needed Secrets enzymes for digestion (Pancreatic Juice) Secretes Sodium Bicarbonate to balance PH in intestines (Produces insulin-and glucagon to lowers and raise blood glucose levels)

16. Digestive Enzymes Active SiteEnzymeEffect on food MouthSalivary Amylase Breaks down starches StomachPepsinBreaks down proteins Small intestine (from pancreas) Trypsin Amylase Lipase Continues the breakdown of proteins Continues the breakdown of starch Breaks down fats Small intestineSucrase Maltase Lactase Lipase Peptidase Breaks down remaining disaccharides into monosaccharides Breaks down fats Breaks down dipeptides into amino acids

17. Large Intestine Main function- Absorb water Produce vitamin K with the help of E. Coli bacteria that live in the large intestine 1.5 meters long Takes 18-24 hrs for waste to reach here Rectum-Storage of waste until it is eliminated Total time for digestion and elimination -24-33 hrs.

18. Nutrition Energy in food is measured in Dietary Calories (Big C) 1 Calorie = 1000 calories Average American teenager needs to take in 2200-2800 Calories per day 6 basic nutrients: carbohydrates, fats, proteins, vitamins, minerals, and water

19. Carbohydrates Bread, pasta, fruits Main source of energy for our body Break down complex sugars into simple sugars (glucose) Use glucose for ATP production Store excess in liver as glycogen. Some gets converted to fats for storage. 1g carb = 4 Calories

20. Fats Dairy, meats, nuts Provides energy and building blocks for your CELL MEMBRANE (phospholipids) and hormones Fats are broken down into fatty acids and glycerol 1g fat= 9 Calories

21. Protein Meat, beans, eggs Raw material for growth, repairs skin and muscle Also used in transport and regulatory functions such as hemoglobin and insulin. Broken down into the individual amino acids (20 essential) to make enzymes, antibodies, hormones Also need Nitrogen to make DNA and RNA for mitosis and protein production 1g protein = 4 Calories

22. Vitamins Vitamins are organic molecules that help to regulate body processes- Vitamins used to maintain growth and metabolism. Needed in small amounts Two kinds- fat soluble- D, E, K, A Can be stored in body and water soluble.- B1, B2, B6, B12, C, Niacin, Folic Acid, Biotin, Choline, Pantothenic Acid Can not be stored in body.

23. Minerals Inorganic nutrients that the body needs. Minerals used for building material or in cellular reactions. Need small amounts Inorganic substances like Fe, Ca, Na, Cl, Mg, P, K, S, I

24. Water Facilitates reactions and maintains homeostasis Makes up the bulk of blood, lymph and body fluids Average person needs to take in at least 1 liter /day Loose water through urine, sweating and exhalation

25. 2000 Calories