3. Introduction The digestive system is used for breaking down food into nutrients which then pass into the circulatory system and are taken to where they are needed in the body.

4. Introduction There are four stages to food processing: 1. Ingestion: taking in food 2. Digestion: breaking down food into nutrients 3. Absorption: taking in nutrients by cells 4. Egestion: removing any leftover wastes

5. The Human Digestive System Begins when food enters the mouth. It is physically broken down by the teeth. It is begun to be chemically broken down by amylase, an enzyme in saliva that breaks down carbohydrates.

6. The Human Digestive System The tongue moves the food around until it forms a ball called a bolus. The bolus is passed to the pharynx (throat) and the epiglottis makes sure the bolus passes into the esophagus and not down the windpipe!

7. The Human Digestive System The bolus passes down the esophagus by peristalsis. Peristalsis is a wave of muscular contractions that push the bolus down towards the stomach.

8. The Human Digestive System To enter the stomach, the bolus must pass through the lower esophageal sphincter, a tight muscle that keeps stomach acid out of the esophagus.

9. The Human Digestive System The stomach has folds called rugae and is a big muscular pouch which churns the bolus (Physical Digestion) and mixes it with gastric juice, a mixture of stomach acid, mucus and enzymes.

10. The Human Digestive System The acid kills off any invading bacteria or viruses. The enzymes help break down proteins and lipids. Chemical Digestion. The mucus protects the lining of the stomach from being eaten away by the acid.

11. The Human Digestive System The stomach does do some absorption too. Some medicines (i.e. aspirin), water and alcohol are all absorbed through the stomach. The digested bolus is now called chyme and it leaves the stomach by passing through the pyloric sphincter.

12. The Human Digestive System Chyme is now in the small intestine. The majority of absorption occurs here. The liver and pancreas help the small intestine to maximize absorption. The small intestine is broken down into three parts:

13. The Human Digestive System 1. Duodenum Bile, produced in the liver but stored in the gall bladder, enters through the bile duct. It breaks down fats. The pancreas secretes pancreatic juice to reduce the acidity of the chyme.

14. The Human Digestive System 2. Jejunum The jejunum is where the majority of absorption takes place. It has tiny fingerlike projections called villi lining it, which increase the surface area for absorbing nutrients.

15. The Human Digestive System Each villi itself has tiny fingerlike projections called microvilli, which further increase the surface area for absorption.

16. The Human Digestive System 3. Ileum The last portion of the small intestine is the ileum, which has fewer villi and basically compacts the leftovers to pass through the caecum into the large intestine.

17. The Human Digestive System The large intestine (or colon) is used to absorb water from the waste material leftover and to produce vitamin K and some B vitamins using the helpful bacteria that live here.

18. The Human Digestive System All leftover waste is compacted and stored at the end of the large intestine called the rectum. When full, the anal sphincter loosens and the waste, called feces, passes out of the body through the anus.

19. Liver the liver has over 500 functions, four being fundamental: production of bile storage of glucose in the form of glycogen (  fat if glycogen limits exceeded), conversion of galactose and fructose to glucose detoxification of the blood (makes enzymes to break down toxins; ex: alcohol, caffeine, nicotine, barbiturates, poisons, excess hormones) deamination of amino acids – removing nitrogen, producing ammonia and eventually urea (excreted by the kidneys)

20. Gallbladder is lodged in one of the lobes of the liver a light muscular bag that stores and releases bile why store bile? We eat large quantities of fats at a time, so having a store of bile is useful but can lead to problems – bile salts can crystallize in the gallbladder forming gallstones back to digestion…. the combination of hormones and the presence of certain foods leads to the secretion of pancreatic enzymes, bile, and intestinal enzymes (maltase, lactase, sucrase and enterokinase), all of which are active in the slightly basic pH of the duodenum

21. the villi of the small intestine are specialized to absorb the molecules of digestion: large surface area transport proteins on the epithelial cells move amino acids, glucose, water soluble vitamins, etc. by facilitated diffusion and active transport into the capillary system, then on to the liver immediately for processing electrolytes by diffusion, water by osmosis fatty acids and glycerol are absorbed into the epithelial cells and are repackaged as triglycerides

22. being hydrophobic, they are packaged into protein packs to enable their transport through the body the packaged fats are absorbed into the lacteals in the interior of the villi, and are transported through the body’s lymphatic system fat soluble vitamins will move with fats into lacteals for absorption in the body

23. Accessory Organs: Pancreas a soft tubular gland that lies just behind the stomach, and is connected to the duodenum by two ducts has both a exocrine (secretory) and endocrine (hormonal) function its exocrine functions are to secrete digestive enzymes and sodium bicarbonate to neutralize the stomach acid and establish a pH of 7.1-8.2 which will not only neutralize the enzyme pepsin, but activate the pancreatic enzymes

24. Pancreatic Enzymes: pancreatic amylase: digest carbohydrates  maltose trypsin: protein digestion: peptides  smaller peptides (activated by enterokinase, secreted by the intestinal wall) chymotrypsin: protein digestion: peptides  smaller peptides (activated by trypsin) peptidase: peptides  smaller peptides and amino acids pancreatic lipase: digests fats into fatty acids and glycerol ribonuclease: digests RNA to nucleotides deoxyribonuclease: digests DNA to nucleotides

25. it receives two separate blood supplies via the portal vein – bringing freshly absorbed nutrients from the small intestine via the hepatic artery – bringing oxygenated blood from the lungs/heart bile each day, the liver secretes between 800 – 1000 mL of bile bile is stored in the gallbladder for release on demand into the small intestine consists of water, bile salts, cholesterol and bile pigments (made from bilirubin – yellow in colour) bile acts as an emulsifier, breaking large fat globules into small ones, allowing lipase more surface area for digestion

26. Digestion and Homeostasis The endocrine, nervous, digestive and circulatory systems all work together to control digestion. Before we eat, smelling food releases saliva in our mouths and gastrin in our stomachs which prepares the body for a snack. The Hormone Gastrin

27. Secretions of the Digestive Tract SecretionSite of productionFunction salivamouthcontributes to starch digestion via salivary amylase; lubricates the inside of the mouth to assist in swallowing mucusmouth, stomach, small intestine, and large intestine protects the cells lining the innermost portion of the digestive tract; lubricates food as it travels through the digestive tract enzymesmouth, stomach, small intestine, and pancreas promote digestion of food masses into particles small enough for absorption into the bloodstream acidstomachpromotes digestion of protein bileliver (stored in gall bladder)suspends fat in water, using bile salts, cholesterol, and lecithin to aid digestion of fats in small intestine bicarbonatepancreas and small intestineneutralizes stomach acid when it reaches the small intestine hormonesstomach, small intestine, and pancreas stimulate production and/or release of acid, enzymes, bile, and bicarbonate; help to regulate peristalsis

28. Digestion and Homeostasis A large meal activates receptors that churn the stomach and empty it faster. If the meal was high in fat, digestion is slowed, allowing time for the fat to be broken down. Hence why we feel fuller after eating a high fat meal.

29. Digestive Disorders

30. Disorders of the digestive system and its accessory organs include: ulcers, inflammatory bowel disease, hepatitis, cirrhosis, and gallstones. All disorders that affect digestion, including eating disorders, can seriously damage overall health by depriving the body cells of the nutrients they need to survive.

31. Questions to Answer Where are Fat Soluble vitamins absorbed? Where are the other vitamins absorbed? What are the fat soluble vitamins? Describe the relationship between the organs in the digestive tract. What are the benefits of having stomach stapling? What are the risks? Summarize chemical digestion of macromolecules. Explain how glucose levels are affected after meals. Include the effects of different foods.

32. Making Healthy Food Choices

33. Good Nutrition + Exercise = Health

34. Digestive Summary Food passes through the digestive tract—the mouth, pharynx, esophagus, stomach, small intestine, and large intestine—during physical digestion. The accessory organs—the salivary glands, liver, gall bladder, and pancreas—supply chemicals that also contribute to the digestion of food as it passes through the digestive tract. The stomach supplies chemicals to aid digestion as well as generating physical contractions to physically break down food. The food is eventually liquefied into soluble units that can pass through cell membranes for transport via the circulatory system to all the cells in the body. The waste materials from the digestive process leave the body via the large intestine.

35. Gastritis

36. Chronic Hepatitis

37. Cirrhosis

38. Jaundice

39. GERD

42. Peptic Ulcer

45. Travel Brochure Project The Body System Travel Agency has just hired you to give tours through the Digestive system. Their first task is to create a travel brochure to highlight the "trendy" spots and exciting activities the systems contain. Also mention any dangers or precautions that tourists should be aware of when visiting each system (Diseases and other issues associated with the digestive system). Use a 8x10 piece of paper to make this brochure. Include: ALL major parts and functions of digestive system – include 8 places/spots that are a must do activity for the family- ex: spa, beach, amusement park, museum, ruins, etc… Must have at least 3 diseases / issues with digestion to avoid Must be in color! Must have pictures! May be hand drawn or done on computer

46. Rubric All major parts of digestive system included: 40 points Functions of each system included: 40 At least two diseases/ issues: 10 Color with pictures: 10