The Digestive System

1. Alejandra Gallegos Cecilia Marquez Skye Rivera The Digestive System

2. The Digestive System is made up of many organs that lets us take food in, which then the organs break down the food both chemically and physically for us to get nutrients. The organs and parts used are the: • Pharynx • Oral Cavity • Tongue • Parotid • Sublingual • Submandibular • Esophagus • Diaphragm • Liver • Gallbladder • Stomach • Pancreas • Pancreatic Duct • Duodenum Salivary Glands • Common Bile Ducts • Small Intestine • Transverse Colon • Ascending Colon • Descending Colon • Cecum • Appendix • Anus • Rectum • Anal Canal

3. Structure • Mouth • There are three salivary glands: • The first being the Parotid gland placed right in front of the ear • The second is the sublingual, which is on the floor of your mouth • The third, the submandibular gland, is right at the jawbone • All three release a good amount of saliva • Esophagus and Throat • The pharynx or the throat is connected to the mouth abd esophagus • The larynx links the throat and trachea together • The esophagus is connected to the throat and stomach, and it is usually flat unless food is coming down from it • The epiglottis blocks the opening of the larynx during swallowing

4. Functions • Just the thought of food provokes the production of saliva and stomach acids. • It all starts in the mouth. The salivary glands, which are on the tongue, produce saliva. Saliva then breaks down the food. The food turns into a moist ball so it’ll be easier to swallow. • When the food is swallowed, it is moved through the throat/pharynx (passage way for food). • The food then travels down to the chest in a tube called the esophagus. Peristalsis is a wave of muscles that pushes the food down to the stomach. • When food reaches the end of • the esophagus, a muscular • ring named the sphincter, • lets food enter and closes • to keep the food/fluid inside • the stomach. The stomach • then churns and mixes the • food with acids and enzymes to • break the food down.

5. Esophagus • The tongue, soft palate, throat (pharynx), epiglottis, esophagus, and several muscles are involved in swallowing which has three stages: (the last being involuntary, cannot be consciously controlled- only by the brain) • Oral- the bolus of the mushed food is driven into the throat by the tongue, triggering the next stage • Pharyngeal- muscular contractions push down the food inside the oesophagus . To stop the food from going into the nasal passage the soft palate encloses the opening and the tongue does the same thing, it stops food from coming back inside the mouth. The epiglottis stops the airway so breathing stops or decreases for a moment. • Esophageal- the food bolus is then brought to the stomach by peristalsis, muscle contractions

6. Stomach • When the food gets to the stomach, a J-shaped organ mixes the food and drenches it in protein digesting enzymes, gastric juice, it widens. • Two different digestions are occurring and when put together it produces chyme. • The protein is then broken down more by gastric juices and three layers of muscle in the stomach creates the waves of peristalsis. • As the food mixes it pushes towards the pyloric sphincter at the stomachs exit. • The chyme then is squirted into the small intestine passing the pyloric valve (sphincter).

7. Small Intestine • Most important part of the Digestive System along with the help from the pancreas and gallbladder to extract the nutrients from the food into the bloodstream. • Gallbladder- a muscular bag that stores bile, made by the liver, then releases bile to the bile ducts to help digestion from fat • Pancreas- makes pancreatic juice , containing break down enzymes, releasing it into the pancreatic ducts and then mixes with the bile before being at the duodenum • There are three parts to the small intestine: • Duodenum- (smallest part of small intestine) job is to get the food from the stomach • Jejunum & Ileum- (together as one creates the largest part of the small intestine) and also where the last stages of the digestion takes place. • Two stages of digestion occurs • First, as the food is being pushed through the small intestine the pancreatic enzymes are digesting the nutrient molecules from the food. • Second, the same enzymes attach to villi, the fingerlike structure that absorb the nutrients

8. Liver • Being the largest internal organ the liver plays a big role in keeping homeostasis and does that by doing metabolic and regulatory functions to the blood’s composition at an equal level • Hepatocytes are the working units of liver and are in good ordered units called lobules • After digestion things like glucose, fatty acids, and amino acids go to the bloodstream after digestion • Liver cells gather glucose and if there are more than need then the extras will be stored in glycogen • Fatty acids are broken down by liver cells to get energy or it can be stored as fat • Amino acids are broken down also releasing some energy and converting their nitrogen into urea, which comes out in urine • Several vitamins are stored or even stockpiled if needed and the liver can store up to 2 years worth

9. Diseases • Gastroesophageal Reflux Disease (GERD)- a case were the food in the stomach begins to leak, going back into the esophagus, which can really irritate the esophagus, causing heart burns, trouble swallowing, dry cough, asthma symptoms, burning pains in the chest and abdomen • The lower esophageal sphincter, almost like a valve that controls what goes into the stomach from the esophagus, opening randomly at different times • It can also be that the esophageal sphincter doesn’t close the right way so the food can come back up again • There isn’t an exact reason for why this happens, but in a research people that have this disease have a working esophagus, but their lower esophageal sphincter is relaxed • Proton pump inhibitors (PPIs) decrease the amount of acid produced in your stomach • H2 blockers (antagonists) lower the amount of acid released in the stomach

10. Crohn’s Disease- the inflations of any part of the digestive tract and the most commonly affected area is in the small intestine called the ileum • The swelling causes pain and makes the intestine and bowel empty, which then leads to diarrhea • When not treated there will be scars leaving a stricture, making the intestine smaller and harder for food to pass through, creating more pain for the person • Men and women can get this disease equally and is more of a genetic dissease than something random • Some researchers believe that the immune system is killing beneficial bacteria instead of the harmful ones • Symptoms are rectal bleeding, diarrhea, and weight loss • Eating small amounts of food throughout the day. • Drinking lots of water (drink small amounts often throughout the day). • Avoiding high-fiber foods (bran, beans, nuts, seeds, and popcorn). • Avoiding fatty, greasy or fried foods and sauces (butter, margarine, and heavy cream).

11. Irratible Bowel Syndrome (IBS)- where pain in the abdomen and diarrhea are both occurring for years, but no other problems, detectable problems, are occurring in the body • Caused by stress and if lasts too long an infection in the intestine will start • No disease is actually found not structurally • Tests will be taken in order to cross off possible reasons for the symptom • Weird muscle contractions will occur and the body will be more sensitive when you stretch • Avoid foods and drinks that stimulate the intestines (such as caffeine, tea, or colas) • Avoid large meals • Increase fiber in the diet (this may improve constipation but make bloating worse)

12. Large Intestine • The last phase of digestion happens in the large intestine, which is only a quarter length of the small intestine, but two times the width of the small intestine • The large intestine contains the: • Cecum • Colon- longest part of the intestine and moves the waste out of the body • Rectum- stores feces and when ready it contracts to remove the waste from the body through the anus • The intestine turns the waste coming from the small intestine into what is called feces • During segmentation, peristaltic contractions, and mass movements, the large intestine reabsorbs salts and waters to keep and equal level of water and be hydrated

13. Citation Book Roberts, Dr.Alice. "The Digestive System." The Complete Human Body. New York: Liz Wheeler, 2010. 78 and 350-363. Print. Internet "Slide show: See how your digestive system works - MayoClinic.com." Mayo Clinic. N.p., n.d. Web. 11 May 2013. <http://www.mayoclinic.com/health/digest ive- system/DG00021&slide=6>. Magazine Winters, Dan. "Your Digestive System." Women's Health 24 Jan. 2006: n. pag. women'shealthmag. Web. 10 May 2013.