Lilian Gonzalez Sean-Paul Gouw

o Digestion is important for breaking down food into nutrients o Food is broken down into smaller molecules o The body uses this for energy, growth, and cell repair

 Digestive Tract (GI)-long, twisted tube  Starts at the mouth and ends at the anus o Organs that make up the GI tract are: mouth, esophagus, stomach, Small Intestine, Large Intestine (includes the rectum and anus) o Digestive Organs include: liver, pancreas, and gallbladder are the solid organs of the digestive system

pancreas  produces enzymes to digest proteins & starch stomach  kills germs  break up food  digest proteins  store food mouth  break up food  digest starch  kill germs  moisten food liver  produces bile - stored in gall bladder  break up fats

Composed of three sections (duodenum, jejunum, and ileum) Site of absorption of nutrients types: passive absorption, facilitated absorption, active absorption, and endocytosis (phagocytosis and pinocytosis) Huge surface area with modified structures called villi and microvilli Villi - fingerlike projections of mucosa, contains blood capillaries and lacteals (small lymph capillaries) Microvilli - tiny projections on cell membranes of absorptive (brush border) cells that contain enzymes (brush border enzymes) used to complete digestion

 Function-absorbs water from the remaining indigestible food matter and transmit the useless waste material from the body. Three sections: ascending, transverse, and descending colon Site of water absorption and packaging waste material Associated with the colon is the appendix

1.Ingestion o Food is taken to the alimentary canal o Process that takes place in the mouth (chewing, grinding, and swallowing) - Chemical effects of saliva are released from the salivary glands - Swallowing of food sends it to the digestive tract 2. Digestion Process by which food is broken down in the earlier stages of the alimentary canal into a form it can be absorbed into the tissues of the body. 2 types: Mechanical (chewing,grinding, mixing) & Chemical (enzymes/acids) 3. Absorption/Assimilation-uptake of fluids by the tissues of the body, chemicals from food taken into the cells of the body 4. Elimination-excretion of metabolic waste products

 Regulating pH levels  Glucose regulation  Absorbed into blood and taken to liver through hepatic portal vein  When digestion is complete, the body is in a post-absorptive state, glucose levels fall. Caloric imbalance can help lose or gain weight Hormones  Gastrin -Stomach -Stimulates gastric acid production  Secretin - In lower small intestine - Regulates small intestine acidity  Motilin -Lower small intestine -Increase pepsin production

 Affected by hormones the Endocrine system produces -Cells secrete hormones in response to certain stimuli  Ex: stomach acid from burning small intestine Transport -Passive Transport  Tea bags  Dissolved nutrients move through walls of small intestine and blood vessels using energy -Active Transport  Chewing (muscle contraction) uses energy  ATP –to transport digested material across the membrane

 Enzymes break down large food molecules into smaller ones Special enzyme in the mouth(amylase) helps break down starch into smaller pieces  Speed up the process of digestion by lowering the activation energy for the reaction  Work at body temperature  Digestion can occur naturally at body temperature, however this process takes a very long time as it happens at such a slow rate.

 Mouth-Carbohydrates are broken down by amylase into maltose and then move down the esophagus  Duodenum- disaccharides are broken down into monosaccharides by enzymes called: maltase, sucrose, and lactase  Stomach-proteins are broken down into peptides, which are then broken down into a single amino acid  Lipids- are digested mainly in the small intestine by bile salts through (emulsification) Lipases divide lipids into fatty acids

 Earthworm (digestive system)-a simple tube of specialized tissues that can absorb nutrients

 The immune reaction to eating gluten creates an inflammation damaging the Small intestine’s lining  Symptoms: pain in the abdomen/joints, diarrhea, bloating, vomiting, heartburn, cramping  Prevent: eating a gluten- free diet  Treatments: prescription- folic acid &gluten-free diet  1% of the population

 "IB Guides." IB Biology Notes. N.p., n.d. Web. 25 May  Mader, Sylvia S. Biology. 10th ed. New York: McGraw Hill,  "Overview of the Digestive Process." Digestive Processes. N.p., n.d. Web. 23 May  Smith, Margaret E., and Dion G. Morton. The Digestive System. Edinburgh: Churchill Livingstone, Print.  Taylor-Butler, Christine. The Digestive System. New York: Children's, Print.  "The Digestive System Diagram, Organs, Function, and More." WebMD. WebMD, n.d. Web. 23 May  Windelspecht, Michael. The Digestive System. Westport, CT: Greenwood, Print.  "Your Digestive System and How It Works." Your Digestive System and How It Works. N.p., n.d. Web. 23 May 2015.