Gastrointestinal System

Gastrointestinal System


  • Gastrointestinal system: Digests and transport food. Absorbs nutrients and eliminates body wastes.

    • Begins with a long muscular tube to the mouth, esophagus, stomach, small intestine, large intestine and anus

  • Organs

    • Mouth: the buccal cavity, first stage of digestion

      • Tongue: contains taste buds

      • Teeth: breaks down food so it can be swallowed easily

      • Salivary glands: produces saliva and chemical breakdown  to lubricate the mouth to make swallowing easier. Produces 1-1.5 quarts of saliva each day

      • Hard palate: roof of mouth that separates the mouth and the nasal cavity

      • Soft palate: separates mouth and nasopharynx’

      • Uvula: prevents food from entering the lungs during swallowing

    • Pharynx (throat)

      • After food is mixed with saliva through the throat as a bolus. When the bolus is swallowed, 

    • Esophagus

      • A muscular tube that carries the bolus to the stomach.

    • Stomach: chemical digestion begins, can hold food for 1-4 hours

      • Receives food from the esophagus. Mucous membrane lining esophagus that contains rugae that disappears as the stomach fills

      • Cardiac sphincter: located between esophagus and  stomach

      • Pyloric sphincter: between small intestine and stomach

      • Chyme: semisolid material in the stomach.

      • Gastric juices: has HCl acid (kills pathogens), aids iron absorption, activates pepsin (breaks down protein), contains lipase (breaks down fats into fatty acids and glycerol)

    • Small intestine

      • The intestines is where most of the absorption during digestion takes place

      • The small intestine has three parts: Duodenum, Jejunum, and ileum

      • Duodenum: digests food coming from the stomach to the jejunum

      • Jejunum: the middle part of the small intestine. Digests food and located between the duodenum and the ilium

      • Ileum: the last part of the small intestine. It connects to the cecum, the first part of the large intestine

    • Large intestine

      • Cecum- connected to the ileum or small intestine

      • Ascending colon: cecum to lower part of intestine

      • Transverse colon: across intestine

      • Descending colon: From the transverse colon to the anus

      • Sigmoid Colon: located between the anus and the descending colon

      • No digestive enzymes are found n the large intestine

      • Some vitamins and minerals are absorbed into the bloodstream

      • More CHO are are activated upon bacteria

      • Water is absorbed to turn wastes into solid

      • Any nutrient available are absorbed before they are eliminated

      • Absorption of B-complex vitamins and vitamin are produced by bacteria

    • Appendix

      • Function is unknown. Appendix is not needed and can be removed

    • Liver

      • Located below the diaphragm

      • Functions:

        • Helps control amount of protein and sugar in the blood

        • Stores sugar and vitamins

        • Produces blood proteins (prothrombin and fibrinogen)

        • Produces bile (carried to the small intestine to help with digestion and absorption). Bile is stored in the gallbladder.

        • Detoxifies bacteria and substances in the blood from the small intestine

    • Gallbladder

      • Located at the underside of the liver

      • A small muscular sac  that holds 2 ounces of bile

      • Releases bile into the small intestine for absorption

    • Pancreas

      • Located behind the stomach

      • Produces digestive enzymes: trypsin and chymotrypsin (breaks down proteins), lipase and steapsin (breaks down fats)

      • Both endocrine and exocrine

      • Aids the digestion in the duodenum

      • Produces insulin and glucagon into the bloodstream


  • Aging Changing in the Digestive System

    • Decrease in taste buds and digestive enzymes

    • Loss of Bowel tone

    • Slowing of peristalsis

    • Slower absorption of nutrients

    • Decrease of chewing capacity


  • Diseases and Conditions of the Gastrointestinal System

    • Diverticulosis and Diverticulitis

      • Overview: Diverticulosis is the formation of Diverticula (small bulging pouches/holes that stick out of the descending colon of the large intestine). It comes with little to no symptoms. Overtime, this leads to diverticulitis the inflaming of the diverticula

      • S/S: 

        • Diverticulosis:

          • There are little to no symptoms of diverticulosis. In some cases, you will experience abdomen pain and changes in bowel.

        • Diverticulitis

          • Fever

          • Changes in bowel, can be noticeable in diarrhea and constipation

          • Nausea

          • Tenderness in abdomen when touched

      • Treatment and Preventions

        • Preventions: Exercise regularly, maintain a healthy weight, eat fiber, quit smoking and alcohol use, and maintain proper fluid balance

        • Treatment: have a liquid diet (uncomplicated diverticulitis), antibiotics and surgery (complicated diverticulitis)

    • Helicobacter Pylori

      • Overview: the infection or weakening of stomach lining and duodenum caused by the bacteria Helicobacter Pylori. Can lead to gastritis

      • S/S: burning sensation in stomach, ulcers, nausea, loss of appetite

      • Dx: blood test, breath test, stool culture

      • Tx: H-2 Blockers, Proton pump inhibitors, stomach lining protectors

    • Anal Fissure

      • Overview: Tearing of the small tissue lining the anus. Caused by passing large stools, or constipation

      • S/S: pain during and after bowel movements, blood on stool and toilet paper

      • Tx: Increased fiber and regular fluid intake is needed to heal for a few weeks

    • Steatorrhea

      • Overview: when there is an excessive amount of fat in the stool. Occurs when the digestive system has trouble breaking down and absorbing fats. Caused by conditions that affect the pancreas, liver, and bile ducts

      • S/S: excessive oil in stool, bulky and smelly stool

      • Tx: Dietary changes such as increased fiber intake, less fat/oil intake, medication, and monitoring of the stool

    • GERD

      • Overview: Known as Gastroesophageal Reflux Disease. Occurs when acid from the stomach overflows into the esophagus and mouth

      • Symptoms: Dysphagia, vomiting, heartburn, and chest pain

      • Tx: Diet changes, surgery, antacids

    • Hernia

      • Overview: occurs when a body part in the abd pushes through a weakened area or a natural opening of a body wall

      • S/S: heartburn, stomach distension, dysphagia, chest pain

      • Tx: small meal, surgical repair, staying upright after meals

    • Cirrhosis

      • Overview: when your liver is scared and permanently damaged, causing liver failure

      • S/S: Liver enlargement, Anemia, Indigestion, Nausea, Edema in the leg and feet, Hematemesis, Nosebleed, Jaundice, Ascite 

      • Tx: Rest, alcohol avoidance, and proper nutrition

    • Gallstones

      • Overview: occurs excess bile and cholesterol in the gallbladder accumulates into small lumps

      • S/S: sweating, fever, tachycardia, jaundice, light colored urine, dark colored stool

      • Tx: Medication, gallbladder removal

    • Irritable Bowel Syndrome: 

      • Overview: chronic long term disease that affects the stomach and digestive tract

      • S/S; Cramps or abdominal pain usually related to passing stool, Diarrhea or constipation, Changes in the stool, mucus will make it looks whitish, Excessive gas and bloating 

      • Tx: Increase intake of fiber and fluids, Rifaximin (abx), limit amount of dairy and gluten

    • Crohn’s Disease

      • Overview: Inflammation of the digestive tract, thought to be an autoimmune disorder

      • S/S: diarrhea, cramping/pain in abdomen and weight loss

      • Tx: No cure but drugs that reduce activity in immune system can help

    • Ulcerative Colitis: 

      • Overview: an inflammatory bowel disease that inflames the colon/large intestine and rectum

      • S/S: Diarrhea, Abdominal pain, Bloody stools, Anemia, Delayed growth and development of children

      •  Tx: No cure but treatment is available like surgery or an autoimmune drug 

    • Gastroenteritis

      • Overview: Known as the stomach flu. Caused by food poisoning, infection, and toxins

      • S/S: abdominal cramping, fever, NVD

      • Tx: Medication, rets, abx

    • Intussusception 

      • Overview: when one segment of the intestines folds into another. Not life threatening, but it is better to treat asap

      • Sx: bloody stool, abdominal pain, emesis

      • Tx: 

        • Children: Enema of air and water through the intestines

        • Adults: removal of bowels

    • Colorectal cancer

      • Overview: occurs when cancer cells attack the large intestine

      • S/S: Diarrhea, changes in bowel, abdominal pain, wt loss, bloody stool

      • Tx: Surgery and Chemotherapy

    • Celiac disease: 

      • Overview: when the immune system reacts to the consumption of gluten. It damages the small intestine lining and disables it from absorbing nutrients

      • S/S: Diarrhea, Wt loss, cramping/abdominal pain, bloating, fatigue, constipation

      • Tx: Diet modifications (eat gluten free meals)

    • Pancreatitis

      • Overview: Inflammation of the Pancreas

      • S/S: dehydration, tachycardia, swollen belly, bleeding, wt loss

      • Tx: diet modifications and regular intake in fluids