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.

What is a peptic ulcer?

What is a peptic ulcer?

A defect in the lining of the stomach or the first part of the small intestine.

What causes peptic ulcers?

Helicobacter pylori bacteria, overuse of NSAIDs, smoking, and alcohol use.

What are the symptoms of peptic ulcers?

Pain, bloating, and loss of appetite.

What is the treatment for peptic ulcers?

Antibiotics to target H. pylori.

What is Gastroesophageal Reflux Disease (GERD)?

A condition where the cardiac sphincter does not close tightly, allowing stomach contents and acid to flow back into the esophagus.

What are common symptoms of GERD?

Burning sensation in the chest (heartburn), bad taste in the mouth, pain in the chest, trouble swallowing, hoarseness.

What are the treatments for GERD?

Small meals, avoiding lying down after eating, medications, and possible surgery.

What is Hepatitis?

A viral disease affecting liver function, causing inflammation and potential liver damage.

What are the symptoms of Hepatitis A?

Pale/clay-colored stool and usually resolves within 2 months.

What is the treatment for Hepatitis B?

Interferon and long-term symptom management; a vaccine is available after birth.

What symptoms are associated with Hepatitis C?

Pale/clay-colored stool, swelling in legs, feet, and ankles.

What is Ulcerative Colitis?

A chronic inflammatory bowel disease causing inflammation in the digestive tract.

What are the symptoms of Ulcerative Colitis?

Diarrhea (often with blood or pus), abdominal pain, cramping, rectal pain, weight loss, fatigue.

What are some treatment options for Ulcerative Colitis?

Diet changes, medications, and surgical options like colostomy and colectomy.

What are common symptoms of stomach and colon cancer?

Rarely shows early signs and can lead to secondary liver cancer.

How can cancer be prevented?

Through regular exams such as colonoscopies and monitoring benign mucosal tumors.