Digestive System Organs: Liver, Gallbladder, Stomach

Digestive System Organs: Liver & Gallbladder

• The liver is the largest gland, positioned below the diaphragm in the upper right quadrant, extending to the upper left quadrant.

• It's a vital organ, producing bile (over a pint daily), which is continuously secreted through bile passages to the bile duct.

• The gallbladder is a small sac attached to the liver's underside.

• Its function is concentrating and storing bile.

• When needed for digestion, the gallbladder releases concentrated bile (green-yellow) through the cystic duct, which combines with the hepatic duct to form the common bile duct.

Stomach: Structure and Function

• The stomach is a J-shaped organ (10 inches long) located beneath the diaphragm.
• It has three layers of strong muscle tissue, enabling expansion to hold about half a gallon of food and liquid.
• The inner lining has folds called rugae.
• The cardiac sphincter regulates the opening, allowing food entry and preventing backflow.

Stomach: Digestive Process

• The stomach's muscular layers contract rhythmically, breaking down food into smaller particles (mechanical digestion).

Gastric Glands and Enzymes

• The stomach contains gastric glands secreting hydrochloric acid and various enzymes (e.g., rennin, lipase, pepsin).
• Rennin curdles milk, lipase breaks down fats, and pepsin digests proteins.
• Hydrochloric acid forms compounds aiding pepsin's protein digestion, and the mucus lining protects the stomach from acid.

Chyme Formation

• After 3-5 hours, partially digested food forms chyme (a semiliquid substance).
• Carbohydrates, proteins, and fats are digested in this order.

Vomiting Mechanism

• The stomach has sphincters that regulate food exit.
• Vomiting involves abdominal muscle contraction and diaphragm pushing down to expel stomach contents.

Small Intestine Parts and Function

• The small intestine (20 feet long, 1 inch diameter) completes the digestive process and absorbs nutrients.
• It has three segments: duodenum (C-shaped, receives stomach acid, prone to ulcer development—duodenal ulcer), jejunum (8 feet), and ileum (12 feet).
• The ileum connects to the large intestine via the ileocecal valve, preventing backward flow.
• The mesentery suspends the small intestine in the abdominal cavity.

Diagnostic Tests: GI X-Ray, Barium Swallow

• Radiologic tests (e.g., GI X-ray), are used to diagnose issues with different segments of the digestive tract.
• A barium swallow helps visualize the esophageal function using barium.
• This test is performed initially to evaluate the esophagus, and barium is consumed while observed through a fluoroscope.

Diagnostic Test: Colonoscopy

• Colonoscopy is a procedure using a flexible fiber-optic scope to view the entire large intestine.
• Useful for detecting issues like diarrhea, constipation, bleeding, and lower abdominal pain.
• The American Cancer Society recommends colonoscopies starting at age 45.

Liver Diseases: Cirrhosis and Colorectal Cancer

• Cirrhosis is a chronic liver disease causing liver cell destruction, impaired blood/lymph circulation, and impaired liver function.
• Early symptoms can include loss of appetite, indigestion, nausea, and diarrhea, progressing to complications like nosebleeds, bleeding gums, edema, and mental confusion.
• Colorectal cancer is malignancy of the colon or rectum, usually the third most common cancer.
• Symptoms vary based on the affected area, starting with right-sided involvement (e.g. black tarry stools; abdominal aching/pressure) then progressing (e.g. chronic diarrhea; incomplete evacuation; later rectal/abdominal pain).

Liver Diseases: Hepatitis

• Hepatitis is liver inflammation and infection, potentially leading to cell destruction and death.
• Types include A (fecal-oral transmission, e.g. contaminated food or water), B (blood/body fluid transmission), and C (blood/body fluid transmission).
• Hepatitis symptoms include fatigue, malaise, head/muscle aches, anorexia, a fever of 100-101°F, and possible nausea/vomiting.
• Hepatitis can be chronic, and treatments include avoiding alcohol; a liquid diet, antibiotics, and anti-diarrheals; often surgery is needed.

Colostomy

• Colostomy is an artificial opening from the colon to the abdominal wall (due to obstructions or tumors), enabling fecal excretion.
• A colostomy is a challenging procedure for both physical and emotional adjustment.

Diverticulosis

• Diverticulosis involves the presence of bulging pouches (diverticula) in the gastrointestinal tract wall.
• Symptoms often include irregular bowel movements, lower abdominal pain, nausea, mild fever, and elevated white blood cells.
  • This procedure can range from minor to involve surgery.

Explore the fascinating functions and structures of key digestive system organs, including the liver, gallbladder, and stomach. Understand the roles these organs play in digestion, from bile production to food storage and processing. This quiz will test your knowledge of the anatomy and physiology of the digestive system.