Gastrointestinal (GI) System

The gastrointestinal system, also called the digestive system, is a group of organs that breaks down food, absorbs its nutrients, and eliminates the unused material

Gastrointestinal System

The gastrointestinal system carries out four main functions in the body

Ingestion is the process by which food, drink, or other substances are taken into the body

Digestion is the process by which food or other substances are broken down into a form that can be absorbed into the tissues of the body

Absorption is the movement of nutrients and water from the digestive system into the circulatory and lymphatic systems

Elimination is the removal of the waste produced during digestion and absorption

Salivary Glands: Secrete saliva

  • Lubricates food which makes swallowing easier

  • Contains enzymes which begin digesting sugar

Gallbladder: Secretes bile

  • The gallbladder stores bile which aids in digesting fat and cholesterol

Pancreas: Secretes enzymes and various secretions

  • Enzymes help digest carbohydrates, fats, and proteins

  • Secretions neutralize stomach acid

Liver: Secretes bile

  • The liver makes bile

  • The liver metabolizes drugs before they reach their target organs, a process called first-pass effect

Gastroesophageal Reflux Disease (GERD)

  • Heartburn

  • Radiating burning or pain in the upper abdomen and chest

  • Acid taste in mouth

  • Worse before meals and while lying down

  • Stomach contents reflux (backflow) into the esophagus because of incompetent lower esophageal sphincter

  • Made worse by alcohol, pregnancy, overeating, smoking, spicy foods, eating late at night

Peptic Ulcer Disease (PUD)

  • Ulcers

  • Causes:

    • Bacterial infection (H. pylori)

    • Physiological stress

    • Medications

      • Aspirin

      • NSAIDS

    • Smoking

    • Gender (males > females)

Inflammatory Bowel Disease: Autoimmune Disorders

Crohn’s Disease

  • Inflammation of the intestines

  • Can affect any part of the GI tract from the mouth to the anus

  • No cure; goal of treatment is to reduce inflammation that triggers signs and symptoms, limiting complications, and possibly long-term remission

  • Symptoms: diarrhea, fever, fatigue, abdominal pain, inflammation outside of intestinal tract (skin, eyes, joints)

Ulcerative Colitis

  • Inflammation only in the large intestine

  • No cure; goal of treatment is to reduce disease severity and decrease the frequency of flares

  • Symptoms: N/V, chills, joint pain

Irritable Bowel Syndrome

  • Common condition that affects the stomach and intestines; symptoms include cramping, stomach pain, bloating, gas, diarrhea, constipation; an ongoing condition

  • Anticholinergic medicines. Medicines such as dicylcomine (Bentyl) can help relieve painful bowel spasms. They are sometimes prescribed for people who have bouts of diarrhea. These medicines are generally safe but can cause constipation, dry mouth and blurred vision.

Nausea and Vomiting

  • Emesis - vomiting

  • Caused when you stimulate the chemoreceptor trigger zone (CTZ)

  • Causes:

    • Viruses

      • Norovirus

      • Rotavirus

    • Pregnancy

    • Medications

    • Chemotherapy

    • Food poisoning

Diarrhea

  • Loose stools

  • Causes:

    • Bacterial or viral infection

    • Parasite

    • Crohn’s disease

    • Ulcerative Colitis

    • IBS

    • Medications

      • Antibiotics

      • Metformin

    • Can lead to dehydration

    • Should not treat short term or infectious diarrhea with OTC medications unless absolutely necessary

  • Treatment:

    • BRAT Diet

      • Bananas

      • Rice

      • Applesauce

      • Toast

    • Adsorbent Agents - soak up water from fecal matter (Kaopectate)

    • Antimotility drugs - slow peristalsis (smooth muscle contractions)

    • Antibiotic or antibacterial agents

Constipation

Constipation is a condition in which the feces are hard and dry and bowel movements are infrequent or irregular.

  • Symptoms include:

    • Abdominal pain

    • Bloating

    • Feeling as if one has not completely passed the bowel movement

  • Causes:

    • Blockages in the colon or rectum

    • Sedentary lifestyle

    • Problems with the nerves around the colon and rectum (MS, stroke, spinal cord injury)

    • Diabetes

    • Pregnancy

    • Thyroid Disease

    • Opioids

    • Dairy foods

  • Treatment:

    • Diets high in fiber

    • Exercise

    • Increased fluid intake

    • Decreased caffeine

    • Fiber supplements (psyllium)

      • Must drink lots of fluid

      • Treats both constipation and diarrhea

    • Stool softeners

    • Laxatives

Laxatives and Stool Softeners

  • Osmotic agents - draw fluid into the colon for easier passage of stool

  • Stool softeners - add moisture to the stool, allowing strain-free bowel movement

  • Stimulant laxatives - increase peristalsis

  • Bulking agents (fiber supplements)

    • Not digested but absorb liquid in the intestines and swell to form a bulky stool (treats both constipation and loose stools)