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Digestive System Notes Alimentary Canal (Gastrointestinal Tract) The continuous tube through which food passes, allowing digestion and absorption of nutrients. Organs Included: 1. Mouth: • Entry point for food. • Mechanical digestion via chewing (teeth). • Chemical digestion begins with saliva containing amylase. 2. Pharynx: • Passageway for food, fluids, and air. 3. Esophagus: • Propels food to the stomach using peristalsis. 4. Stomach: • Function: Temporary storage tank for food. • Mixes food with gastric juices for breakdown into chyme. • Secretes pepsin (breaks down proteins). 5. Small Intestine: • Divisions: • Duodenum. • Jejunum. • Ileum. • Primary site of nutrient absorption. • Receives bile (from liver) and pancreatic juices (from pancreas) to aid digestion. 6. Large Intestine: • Divisions: • Cecum, appendix, colon (ascending, transverse, descending, sigmoid), rectum, anal canal. • Functions: • Absorbs water. • Houses bacterial flora for vitamin synthesis. • Forms and eliminates feces. 7. Rectum and Anal Canal: • Stores feces for elimination. Accessory Digestive Organs These organs assist the alimentary canal by producing or storing substances necessary for digestion. Organs Included: 1. Teeth: • Primary Teeth: 20 deciduous teeth erupt between 6 and 24 months. • Permanent Teeth: 32 permanent teeth appear between 6 and 12 years. • Classifications: • Incisors: For cutting and nipping. • Canines: Fang-like for tearing and piercing. • Premolars (Bicuspids) and Molars: Broad crowns for grinding and crushing. 2. Tongue: • Mostly skeletal muscle. • Functions: • Contains taste buds to analyze nutrient content of food. • Mixes food with saliva to form a bolus. • Aids in swallowing. 3. Salivary Glands: • Function: Produce and secrete saliva (water-based liquid containing amylase) for chemical digestion. • Types: • Parotid glands. • Submandibular glands. • Sublingual glands. • Fun Fact: Mumps infect the parotid glands. 4. Liver: • Secretion: Produces bile, a greenish liquid (pH 7.6–8.6) essential for fat digestion. • Functions of Hepatocytes: • Produce bile. • Process nutrients from blood. • Store fat-soluble vitamins. • Detoxify harmful substances. 5. Gallbladder: • Thin-walled muscular sac on the liver’s ventral surface. • Functions: • Stores and concentrates bile. • Releases bile into the duodenum to emulsify fats. • Disorders: • Gallstones causing blockages and pain. • Extreme cases can result in gallbladder rupture. 6. Pancreas: • Exocrine Function: • Produces pancreatic juice containing enzymes for digesting carbohydrates, proteins, and lipids. • Endocrine Function: • Secretes insulin to regulate blood glucose levels. • Disorders: Malfunction can cause diabetes. Important Notes About Digestive System Processes 1. Ingestion: Intake of food through the mouth. 2. Propulsion: • Swallowing. • Peristalsis (waves of muscle contractions moving food through the tract). 3. Mechanical Digestion: • Chewing (mouth). • Churning (stomach). • Segmentation (small intestine). 4. Chemical Digestion: • Breakdown of food molecules by enzymes. 5. Absorption: • Movement of nutrients into blood or lymph via small intestine. 6. Defecation: • Elimination of indigestible substances and waste products as feces.
Digestive System Diseases
1. Peptic Ulcers
• What it is:
• A defect in the lining of the stomach (gastric ulcer) or the first part of the small intestine (duodenal ulcer).
• Caused when the lining of the stomach or small intestine breaks down.
• Causes:
• Helicobacter pylori (H. pylori) bacteria.
• Overuse of NSAIDs (e.g., Advil, aspirin).
• Smoking cigarettes, alcohol use.
• Symptoms:
• Pain, bloating, and loss of appetite.
• Treatment:
• Antibiotics to target H. pylori.
• Risk Factors:
• Stress (not clearly proven), alcohol, smoking, overusing NSAIDs.
2. Gastroesophageal Reflux Disease (GERD)
• What it is:
• A condition where the band of muscle (cardiac sphincter) connecting the esophagus to the stomach does not close tightly, allowing stomach contents and acid to flow back into the esophagus.
• Symptoms:
• Burning sensation in the chest (heartburn).
• Bad taste or burning sensation in the back of the mouth.
• Pain in the chest, trouble swallowing, hoarseness.
• Treatment:
• Small meals.
• Avoid lying down for 3+ hours after eating.
• Medications (antacids, H₂ blockers, proton pump inhibitors).
• Surgery to tighten the muscle.
• Risk Factors:
• Alcohol, smoking, being overweight, pregnancy.
3. Hepatitis
• What it is:
• A viral disease that affects liver function, causing inflammation and potential liver damage.
• Types:
• Hepatitis A:
• Contracted from contaminated food or water.
• Symptoms: Pale/clay-colored stool.
• Severity: Liver usually heals itself within 2 months; rarely fatal.
• Treatment: Monitor liver function; vaccine available.
• Hepatitis B:
• Contracted from body fluid exchange or mother-to-fetus transmission.
• Symptoms: Stomach pain, aching joints.
• Severity: Most recover within 6 months but can cause lifelong damage in severe cases.
• Treatment: Interferon and long-term symptom management; vaccine available after birth.
• Hepatitis C:
• Contracted from blood contact (e.g., transfusions).
• Symptoms: Pale/clay-colored stool, swelling in legs, feet, and ankles.
• Severity: Causes severe liver damage, leading to liver transplants.
• Treatment: Interferon, Ribavirin, and long-term symptom management (with severe side effects).
4. Ulcerative Colitis
• What it is:
• A chronic inflammatory bowel disease causing inflammation in the digestive tract.
• Symptoms:
• Diarrhea (often with blood or pus).
• Abdominal pain, cramping, rectal pain, rectal bleeding.
• Urgency to defecate but inability to do so.
• Weight loss, fatigue, fever.
• Treatment:
• Diet changes.
• Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, antibiotics, IV fluids, immunosuppressive drugs (e.g., Stelara, Humira, Remicade).
• Surgical options: Colostomy, ileostomy, colectomy, or proctocolectomy.
5. Cancer (Stomach and Colon Cancer)
• What it is:
• Stomach and colon cancers are serious conditions with late-onset symptoms.
• Colon cancer is the 2nd leading cause of cancer death in males (lung cancer is 1st).
• Symptoms:
• Rarely show early signs.
• Can metastasize and cause secondary liver cancer.
• Prevention:
• Regular exams (dental exams for mouth cancer, colonoscopy for colon cancer).
• Benign mucosal tumors (polyps) increase with age but should be tested for cancer.
Digestive System Notes Alimentary Canal (Gastrointestinal Tract) The continuous tube through which food passes, allowing digestion and absorption of nutrients. Organs Included: 1. Mouth: • Entry point for food. • Mechanical digestion via chewing (teeth). • Chemical digestion begins with saliva containing amylase. 2. Pharynx: • Passageway for food, fluids, and air. 3. Esophagus: • Propels food to the stomach using peristalsis. 4. Stomach: • Function: Temporary storage tank for food. • Mixes food with gastric juices for breakdown into chyme. • Secretes pepsin (breaks down proteins). 5. Small Intestine: • Divisions: • Duodenum. • Jejunum. • Ileum. • Primary site of nutrient absorption. • Receives bile (from liver) and pancreatic juices (from pancreas) to aid digestion. 6. Large Intestine: • Divisions: • Cecum, appendix, colon (ascending, transverse, descending, sigmoid), rectum, anal canal. • Functions: • Absorbs water. • Houses bacterial flora for vitamin synthesis. • Forms and eliminates feces. 7. Rectum and Anal Canal: • Stores feces for elimination. Accessory Digestive Organs These organs assist the alimentary canal by producing or storing substances necessary for digestion. Organs Included: 1. Teeth: • Primary Teeth: 20 deciduous teeth erupt between 6 and 24 months. • Permanent Teeth: 32 permanent teeth appear between 6 and 12 years. • Classifications: • Incisors: For cutting and nipping. • Canines: Fang-like for tearing and piercing. • Premolars (Bicuspids) and Molars: Broad crowns for grinding and crushing. 2. Tongue: • Mostly skeletal muscle. • Functions: • Contains taste buds to analyze nutrient content of food. • Mixes food with saliva to form a bolus. • Aids in swallowing. 3. Salivary Glands: • Function: Produce and secrete saliva (water-based liquid containing amylase) for chemical digestion. • Types: • Parotid glands. • Submandibular glands. • Sublingual glands. • Fun Fact: Mumps infect the parotid glands. 4. Liver: • Secretion: Produces bile, a greenish liquid (pH 7.6–8.6) essential for fat digestion. • Functions of Hepatocytes: • Produce bile. • Process nutrients from blood. • Store fat-soluble vitamins. • Detoxify harmful substances. 5. Gallbladder: • Thin-walled muscular sac on the liver’s ventral surface. • Functions: • Stores and concentrates bile. • Releases bile into the duodenum to emulsify fats. • Disorders: • Gallstones causing blockages and pain. • Extreme cases can result in gallbladder rupture. 6. Pancreas: • Exocrine Function: • Produces pancreatic juice containing enzymes for digesting carbohydrates, proteins, and lipids. • Endocrine Function: • Secretes insulin to regulate blood glucose levels. • Disorders: Malfunction can cause diabetes. Important Notes About Digestive System Processes 1. Ingestion: Intake of food through the mouth. 2. Propulsion: • Swallowing. • Peristalsis (waves of muscle contractions moving food through the tract). 3. Mechanical Digestion: • Chewing (mouth). • Churning (stomach). • Segmentation (small intestine). 4. Chemical Digestion: • Breakdown of food molecules by enzymes. 5. Absorption: • Movement of nutrients into blood or lymph via small intestine. 6. Defecation: • Elimination of indigestible substances and waste products as feces.
Digestive System Diseases
1. Peptic Ulcers
• What it is:
• A defect in the lining of the stomach (gastric ulcer) or the first part of the small intestine (duodenal ulcer).
• Caused when the lining of the stomach or small intestine breaks down.
• Causes:
• Helicobacter pylori (H. pylori) bacteria.
• Overuse of NSAIDs (e.g., Advil, aspirin).
• Smoking cigarettes, alcohol use.
• Symptoms:
• Pain, bloating, and loss of appetite.
• Treatment:
• Antibiotics to target H. pylori.
• Risk Factors:
• Stress (not clearly proven), alcohol, smoking, overusing NSAIDs.
2. Gastroesophageal Reflux Disease (GERD)
• What it is:
• A condition where the band of muscle (cardiac sphincter) connecting the esophagus to the stomach does not close tightly, allowing stomach contents and acid to flow back into the esophagus.
• Symptoms:
• Burning sensation in the chest (heartburn).
• Bad taste or burning sensation in the back of the mouth.
• Pain in the chest, trouble swallowing, hoarseness.
• Treatment:
• Small meals.
• Avoid lying down for 3+ hours after eating.
• Medications (antacids, H₂ blockers, proton pump inhibitors).
• Surgery to tighten the muscle.
• Risk Factors:
• Alcohol, smoking, being overweight, pregnancy.
3. Hepatitis
• What it is:
• A viral disease that affects liver function, causing inflammation and potential liver damage.
• Types:
• Hepatitis A:
• Contracted from contaminated food or water.
• Symptoms: Pale/clay-colored stool.
• Severity: Liver usually heals itself within 2 months; rarely fatal.
• Treatment: Monitor liver function; vaccine available.
• Hepatitis B:
• Contracted from body fluid exchange or mother-to-fetus transmission.
• Symptoms: Stomach pain, aching joints.
• Severity: Most recover within 6 months but can cause lifelong damage in severe cases.
• Treatment: Interferon and long-term symptom management; vaccine available after birth.
• Hepatitis C:
• Contracted from blood contact (e.g., transfusions).
• Symptoms: Pale/clay-colored stool, swelling in legs, feet, and ankles.
• Severity: Causes severe liver damage, leading to liver transplants.
• Treatment: Interferon, Ribavirin, and long-term symptom management (with severe side effects).
4. Ulcerative Colitis
• What it is:
• A chronic inflammatory bowel disease causing inflammation in the digestive tract.
• Symptoms:
• Diarrhea (often with blood or pus).
• Abdominal pain, cramping, rectal pain, rectal bleeding.
• Urgency to defecate but inability to do so.
• Weight loss, fatigue, fever.
• Treatment:
• Diet changes.
• Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, antibiotics, IV fluids, immunosuppressive drugs (e.g., Stelara, Humira, Remicade).
• Surgical options: Colostomy, ileostomy, colectomy, or proctocolectomy.
5. Cancer (Stomach and Colon Cancer)
• What it is:
• Stomach and colon cancers are serious conditions with late-onset symptoms.
• Colon cancer is the 2nd leading cause of cancer death in males (lung cancer is 1st).
• Symptoms:
• Rarely show early signs.
• Can metastasize and cause secondary liver cancer.
• Prevention:
• Regular exams (dental exams for mouth cancer, colonoscopy for colon cancer).
• Benign mucosal tumors (polyps) increase with age but should be tested for cancer.
