DIGESTION OVERVIEW I Process of digestion II Trip

DIGESTION OVERVIEW I. Process of digestion II. Trip through the Digestive System III. Problems of the digestive system ND-1

I. Process of Digestion A) Breakdown of food: • Food is broken down by the digestive system. • Digestion changes food into a usable form the cells can use.

Where does the digestive system start and end? • • Mouth Pharynx esophagus stomach small intestine large intestine (also called the colon) rectum anus

What is the digestive system? • made up of the digestive tract—a series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food • Food is changed into a usable food by some type of chemical • Enzymes help speed up the changing of food into a usable form

Enzymes help speed up the changing of food into a usable form • Fats, proteins and carbs must be broken down by enzymes • Vitamins, Minerals and water do not have to be broken down.

II. Trip through the Digestive System 1. Mouth 2. Esophagus 3. Stomach 4. Small Intestine - pancreas - liver - gallbladder 5. Large intestine 6. Anus Organ Chart • SNEAK PEEK

1. Mouth: • Where food enters • Time spent: Few minutes • Production of saliva is the first step in digestion (sometimes before you even start eating) • Tongue moves it around and the saliva produced coats and lubricates the food for easier chewing and swallowing. • Teeth cause only a mechanical change. • Saliva also contains an enzyme called amylase – chemically break down certain carbohydrates

Chemical change in the mouth: amylase • Contained in saliva (salivary glands) • Breaks down sugar and starches (carbs) into smaller components Video

2. Pharynx • Tube connecting mouth to the esophagus • As you swallow the epiglottis covers the windpipe so food does not go down the wrong tube. • Lasts a few seconds • No digestion occurs here

3. Esophagus • Tube connecting mouth to stomach • Few seconds • No digestion occurs here • Peristalsis (muscle contractions) send the food down the tube until it reaches the sphincter (start of the stomach) • Esophagus video

4. Into the Stomach • As food approaches, the sphincter valve opens causing food to go into the stomach. • Time spent: 4 hours • Physical change: mixes and churns the food • Chemical change: 2 enzymes - Pepsin and Rennin • Acid that breaks down food and bacteria • Stores and processes food.

Physical change in the stomach • Hydrochloric acid helps break the food down into smaller pieces • Has a p. H of 1 • Mixes and turns food to break into smaller pieces

Chemical change in the stomach • Pepsin: breaks down protein • Rennin: enzyme that turns milk into cheese • Let’s view the stomach!

5. Through the Small Intestine • Most chemical digestion and absorption occurs here! • 18 -39 feet long on average. . . That's 4 -5 x's longer than you! • The small intestine itself does not make enzymes, but 3 other organs not in the digestive tract deliver enzymes to the small intestine • All 3 nutrients are digested via 3 other organs • Time: 12 hours to digest and absorb

Three parts to the Small Intestine: 1. Duodenum – Located at the junction of the stomach and the small intestine – Receives bile from the gallbladder, and other digestive enzymes from the pancreas ― Bulk of the digestion of proteins, fats and carbohydrates takes place in the duodenum before the material travels further into the small intestine

Three parts to the Small Intestine: 2. Jejunum • coiled mid-section of the small intestine 3. Ileum • final portion of the small intestine, which leads into the large intestine • contain very small finger -like bumbumps called 'villi‘, which improves the small intestine's ability to absorb nutrients.

The Pancreas • The pancreas produces 3 enzymes • Lipase: breaks down fats • Protease: Breaks down protein • Amylase: Breaks • pancreas is a small flat down carbs organ (about 18 -25 cm • Delivers these long) that is located enzymes to small behind the stomach and intestine through the sits close to the pancreatic duct duodenum

The Liver: • Largest organ of the body (except the skin) • Physical change: Makes bile: • BILE: Green, smelly liquid • Breaks fats into smaller fat droplets • Delivers the bile to the gallbladder for storage • Located in the upper abdomen to the right of the stomach, below diaphragm • liver is the body's 'detoxifier‘ • Ammonia - a toxic product arising from the digestion of proteins, is converted into the less toxic 'urea' by the liver and then transferred to the kidneys

The Gall. Bladder • Stores Bile (physical change) • Delivers the bile when needed to the small intestine via the Hepatic Duct • If the bile hardens it forms gallstones. • small (10 cm long) pearshaped organ that is located near the duodenum and the liver.

How are nutrients absorbed? • Absorption: movement of chemicals into or out of an organ • Has villi on the inside that have blood vessels that carry nutrients throughout the body • Villi increase the intestinal surface area • More surface =more absorption

6. Large intestine • Once in the large intestine: digestion is already complete. • Large intestine only does physical changes: removes water from undigested food and begins to produce feces. • Time: 4 hours • 3 parts: Ascending (up) Transverse (across) Descending (down) • Also contains: caecum, appendix, colon and rectum

• Caecum – first part of the large intestine – accepts and stores processed material from the small intestine and moves it towards the colon • Appendix – has no known function and is thought to be a remnant from a previous time in human evolution. • Colon – Shaped like an inverted 'U' – has four sections – mixture of fiber, small amounts of water, and vitamins, etc, mixes with mucus and with bacteria that live in the large intestine to form feces. • Rectum – rectum is the final part of the large intestine. – where stool (feces) is stored before being passed as a bowel motion.

7. Anus • Where waste is excreted: • opening through which stools/feces (ie, the waste products of digestion) pass out of the rectum and are eliminated from the body • nervous system triggers the urge to pass stools. • surrounded by very strong sphincter muscles contract and expand to open the anus and allow stools to pass

Problems of Digestive System -Heartburn • Acid moves into the esophagus • Caused by eating too much food • Many people get acid reflux disease • Take an antacid such as rolaids, tums, pepto-bismol

Problems Of Digestive System -Gallstones • Bile stores up and hardens either in the liver or the gallbladder • Block pathways for digestion • have to have them surgically removed

Problems of Digestive System ULCERS • Sore or hole on inside the stomach or small intestine • Caused by too much HCl & pepsin being produced • Enzymes eat away at stomach lining • Causes burning sensation in stomach • Stress can bring on an ulcer or it is just natural production of too much acid • Prescribed medicine for extreme cases • Minor cases can uses Pepsid AC

Problems of Digestive System -Appendicitis • Swelled appendix • Bacteria builds up from stuck food • Causes severe pain on lower right side of body • Appendectomy – the removal of the appendix

Problems of Digestive System Constipation • Too much water is absorbed by the large intestine • Can be a virus or something one eats • Over the counter medicines usually take care of the problem • Pepto-bismol, eating more roughage (lettuce), etc.

Problems of Digestive System Diarrhea • Not enough water is absorbed by the large intestine • Runny stools • Caused by bacteria or virus or something one ate • Over the counter medicines such as pepto -bismol will help