Comprehensive Review of the Digestive System and Related Disorders

Screening can prevent colon cancer by finding and removing polyps before they progress to cancerous stages.
According to the American Cancer Society, the lifetime risk of developing colorectal cancer is approximately 1/23 or 4.4\%; risk is slightly lower in females.

Stomach Anatomy:
- Located behind the epigastric region in the abdominopelvic area.
- Esophageal Sphincter at the top (connects esophagus with stomach).
- Pyloric Sphincter at the bottom (controls gastric emptying).
- Rugae: folds inside the stomach for secretion of gastric juices.
- Muscle Layers of the stomach:
- Vertical
- Transverse
- Oblique
Function: These muscle layers churn food, mixing gastric substances for digestion.

Function: Produce saliva and enzymes for food breakdown in the mouth.
Three pairs of major salivary glands:
- Submandibular (under lower jaw)
- Sublingual (under the tongue)
- Parotid (near the ear)

Location: Elongated gland stretching transversely across the posterior abdominal wall.
Functions:
- Endocrine: Secretion of insulin and glucagon into the bloodstream.
- Exocrine: Secretion of digestive enzymes into the duodenum.
Structure:
- Divided into head, body, and tail; head is near the duodenum.
- Duct extends throughout the gland for enzyme transport.

Liver:
- Produces bile, detoxifies the body, synthesizes proteins, regulates glycogen storage.
- Largest lobe is the right lobe.
Gallbladder:
- Stores bile, which is emptied into common bile duct and then into the duodenum.
- Bile aids in fat digestion.

Location: Dark purple organ found posterior and inferior to the stomach.
Functions:
- Part of the lymphatic system (contains lymph nodes).
- Hemopoiesis: Production of blood cells (especially during infection).
- Stores about 500 mL of blood.

Mastication: Process of chewing food (mescedure means to chew).
Metabolism: Breakdown of food into energy.
- Catabolism: Breakdown phase (large molecules to smaller, e.g., glycogen o pyruvic ext{ acid}).
- Anabolism: Constructive phase (smaller molecules into larger, e.g., amino ext{ acids} o proteins).

Chyme: Mixture of gastric juices and partially digested food; has yellow-orange color from bile.
Process:
- Chyme passes through the intestines; water is reabsorbed in the large intestine leading to solidification into feces.

Essential Body Nutrients: Carbohydrates, fats, proteins, vitamins, minerals, and water.
Vitamins: Organic substances crucial for metabolism and health.
- Classified into fat-soluble (A, D, E, K) and water-soluble (B, C).

Colonoscopy: Examines the large intestine for polyps, cancers; involves clear liquids and bowel cleansing before procedure.
Proctoscopy: Examines the rectum with specialized instruments for detecting abnormalities.

Hernias: Protrusion of tissue through normal body structures; classifications include inguinal, abdominal, and more.
Fistulas: Abnormal passageways between organs or cavities; can form due to infections, injuries, or congenital issues.
Dysentery: Intestinal infection characterized by diarrhea with mucus and blood; treatment involves hydration and antibiotics.
Cholera: Severe diarrhea caused by Vibrio cholerae; treated through fluid restoration.

Scurvy: Vitamin C deficiency, symptoms include gum bleeding, joint pain; treated with vitamin C supplementation.
Beriberi: Vitamin B1 (thiamine) deficiency, affecting the nervous system.
Pelagra: Niacin deficiency, characterized by multiple bodily symptoms including gastrointestinal disturbances.

Proper nutrition is crucial for health and prevention of diseases. Regular screening for cancer and awareness of digestion-related disorders can significantly affect long-term health outcomes.