Digestive SystemYixuan He

Function• Break up food into smaller pieces. • Transporting food to the GI tract (gastrointestinal) • Secreting digestive enzymes • Absorbing nutrients into the blood• Excreting solid waste products (waste)

Mouth• The mouth is the beginning of the digestive tract• Chewing breaks the food into small pieces• Easily digested

Pharynx and Esophagus• Pharynx• The throat• Receives the food from your mouth.• Swallowing

• A voluntary reflex

• Esophagus• Connects mouth to stomach• A muscular tube extending from the pharynx and behind the

trachea to the stomach• Food is pushed through the esophagus and into the stomach by

means of a series of contractions called peristalsis.

Stomach• Storage bag for food• Secretes acid and powerful enzymes that bread down the food

and change it to a consistency of liquid or paste.• Flexible • Expands when you eat• Can hold up to 3 L of food

• If the stomach could not store food, you would have to eat every twenty minutes or so instead of just three times a day.

Small Intestine• folded into tiny fingerlike projections called villi • Each villus contains blood vessels. • surface area through which nutrients pass to the bloodstream is

greatly increased• If the villi on the inner lining of the small intestine are flattened

out, they would cover about 4500 square meters.• Where most of the nutrient is absorbed through the walls and

into the bloodstream• Breaks down food• Duodenum, Jejunum, and Ileum• Duodenum is largely responsible for the continuing breakdown

process• Jejunum and ileum being mainly responsible for absorption of

nutrients into the bloodstream.

Large Intestine (colon)• five- to seven -foot -long muscular tube that connects the

small intestine to the rectum• absorb water from the undigested food, hold the undigested

food for a while and then excrete it as feces.• Consists of:• cecum• ascending colon• transverse colon• descending colon• sigmoid colon

Rectum and Anus• Rectum • receives stool from the colon• stores some feces and help with defecation

• Anus• dispose of waste products out of the body

Accessory organs• Salivary Glands• Liver• Pancreas• Gallbladder• Sphincters

Salivary Glands• Saliva mixes with food to begin the process of breaking it

down.• Fun fact: The smell of food triggers the salivary glands in your

mouth to secrete saliva, causing your mouth to water. When you actually taste the food, saliva increases.

Liver and Pancreas• Liver• The largest organ inside the body• It produces bile, a substance that helps in the digestion of fats.• Process the blood coming from the small intestine.

• Purifies this blood of many impurities before traveling to the rest of the body.

• Pancreas• Produce pancreatic juice

• Pancreatic juice helps in neutralizing or weakening the acid in food inside the stomach.

• Also contains different enzymes that are needed to further break down starch, proteins and fats in the small intestine.

Gallbladder and Sphincters• Gallbladder• Small muscular sac• Storage sac for excess bile.

• Sphincters• Lower Esophagus Sphincter

• Located Just before the opening to the stomach• Ring-shaped muscle• This sphincter opens to let food pass into the stomach and closes to

keep it there.• If your LES doesn't work properly, you may suffer from a condition

called GERD which causes heartburn and regurgitation • anal sphincters (inner and exterior)

• control the exit of feces from the body

Physical digestion vs. Chemical digestion• Physical• is the breakdown of food by physical means.

• Chemical• molecules of water, vitamins, and minerals are small enough to

be absorbed through the intestinal wall and into the blood stream

• proteins, carbohydrates, and fat molecules are too large and must be broken down further by chemical means. This is chemical digestion.

Physical digestion vs. Chemical digestion

Physical Chemical

• breakdown of food by physical means

• Chewing and churning

• breakdown of food by chemical means

• Acids and enzymes• Digest food

and aid in absorbing nutrients.

Nutrients• Carbohydrates:• Saliva begins carbohydrate digestion with the enzyme salivary

amylase. • The release of Pancreatic Amylase in the duodenum digests the

rest• Protein• Begins in the stomach with HCl and Pepsin.• Inside the small intestine, the pancreatic enzymes trypsin and

chymotrypsin break down the polypeptides.• Lipid• The fat digesting enzyme lingual lipase starts breaking down fat

inside your mouth as you are chewing.• Bile released from the gall bladder

Crohn’s Disease• a chronic inflammatory condition of the gastrointestinal (GI)

tract.• Symptoms:• abdominal pain• diarrhea• weight loss• poor appetite

• Crohn’s disease may affect as many as 700,000 Americans.• Crohn's is more prevalent among adolescents and young adults

between the ages of 15 and 35.• Treatment:• Medication• Surgery

Irritable Bowel Syndrome (IBS)• Irritable bowel syndrome is a functional gastrointestinal (GI)

disorder, meaning it is a problem caused by changes in how the GI tract works.

• Symptoms• Diarrhea• Constipation• Passing mucus• Abdominal bloating

• Affects 3 to 20 percent of the population• Treatment: • Changes in eating, diet, and nutrition• Medication• Probiotics

Bibliography• National Digestive Diseases Information Clearinghouse

(Division of NIDDK/NIH). American Medical Association.• The Cleveland Clinic Foundation• http://

my.clevelandclinic.org/anatomy/digestive_system/hic_the_structure_and_function_of_the_digestive_system.aspx

• Crohn's and Colitis Foundation of America• National Digestive Diseases Information Clearinghouse• http://digestive.niddk.nih.gov/ddiseases/pubs/ibs/

Bibliography (Cont.)• Pictures:

• http://www.google.com/imgres?hl=en&sa=X&tbo=d&biw=1052&bih=535&tbm=isch&tbnid=R9Klud4RSyZ2XM:&imgrefurl=http://www.encognitive.com/node/1122&docid=XQFBGcRLNkvvGM&imgurl=http://www.encognitive.com/images/digestive-system-2.jpg&w=422&h=561&ei=r6sAUdveDMaK2gWyj4HoDA&zoom=1&iact=hc&vpx=451&vpy=137&dur=794&hovh=259&hovw=195&tx=125&ty=138&sig=113692303009654574651&page=1&tbnh=153&tbnw=121&start=0&ndsp=14&ved=1t:429,r:3,s:0,i:160

• http://www.google.com/imgres?hl=en&sa=X&tbo=d&biw=1052&bih=535&tbm=isch&tbnid=jWClj-7x4y8kMM:&imgrefurl=http://en.wikipedia.org/wiki/Human_pharynx&docid=Ce2Gcs2udEo3eM&imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Illu01_head_neck.jpg/250px-Illu01_head_neck.jpg&w=250&h=254&ei=FawAUdnWLqiG2gXFpICwDg&zoom=1&iact=hc&vpx=4&vpy=158&dur=4080&hovh=203&hovw=200&tx=76&ty=119&sig=113692303009654574651&page=1&tbnh=139&tbnw=146&start=0&ndsp=18&ved=1t:429,r:0,s:0,i:151

• http://www.google.com/imgres?hl=en&tbo=d&biw=1052&bih=535&tbm=isch&tbnid=uRaNeVBRR10iYM:&imgrefurl=http://uogirl10-virtualfieldtrip.blogspot.com/2008/05/post-8.html&docid=vOXad7FMIKH2fM&imgurl=http://2.bp.blogspot.com/_pGhDYqqlW5U/SCJvbH59zKI/AAAAAAAAACs/BVCq11bhi4U/s400/Stomach.gif&w=300&h=243&ei=TKwAUbavC-js2AXekoDwDg&zoom=1&iact=rc&dur=359&sig=113692303009654574651&page=1&tbnh=149&tbnw=187&start=0&ndsp=11&ved=1t:429,r:8,s:0,i:172&tx=120&ty=88

• http://www.google.com/imgres?um=1&hl=en&sa=N&tbo=d&biw=1052&bih=535&tbm=isch&tbnid=ibjJ20Hhr_6vfM:&imgrefurl=http://students.cis.uab.edu/ashjones/index3a.html&docid=VbAAZkvKEOsP9M&imgurl=http://students.cis.uab.edu/ashjones/colon3.jpg&w=396&h=300&ei=rKwAUZSxNuX72QWi54GYAw&zoom=1&iact=rc&dur=465&sig=113692303009654574651&page=1&tbnh=134&tbnw=177&start=0&ndsp=11&ved=1t:429,r:3,s:0,i:160&tx=127&ty=59

• http://www.google.com/imgres?um=1&hl=en&sa=N&tbo=d&biw=1052&bih=535&tbm=isch&tbnid=BAURNyL0fQZLwM:&imgrefurl=http://www.alargastro.com/Patient_Education/Large_Intestine.html&docid=v6ZGgB1mjYNowM&imgurl=http://www.alargastro.com/images/Large%252520Intestine.jpeg&w=460&h=300&ei=Ba0AUdWPC4rm2QWkl4DADg&zoom=1&iact=hc&vpx=569&vpy=217&dur=1733&hovh=181&hovw=278&tx=211&ty=116&sig=113692303009654574651&page=1&tbnh=133&tbnw=204&start=0&ndsp=16&ved=1t:429,r:8,s:0,i:175

• http://www.google.com/imgres?um=1&hl=en&tbo=d&biw=1052&bih=535&tbm=isch&tbnid=cBPuui51denENM:&imgrefurl=http://www.cpmc.org/advanced/liver/patients/topics/PancreasCancer-profile.html&docid=lqQQGXFzlRNj3M&imgurl=http://www.cpmc.org/images/liver/topics/PancreasCancer-profile-0.jpg&w=260&h=288&ei=Uq0AUYLxCorm2QWkl4DADg&zoom=1&iact=hc&vpx=803&vpy=140&dur=1788&hovh=230&hovw=208&tx=177&ty=110&sig=113692303009654574651&page=1&tbnh=144&tbnw=130&start=0&ndsp=18&ved=1t:429,r:17,s:0,i:133