AV

Digestive System Notes

Key Components of the Oral and Digestive Systems

  • Teeth Structure
    • Crown: The part of the tooth visible above the gums, covered by enamel, which is the hardest substance in the human body.
    • Root: The part of the tooth located below the gums, anchoring the tooth in the jawbone, typically covered by cementum.
  • Oral Cavity
    • Gums: The soft tissue encasing the teeth, providing a seal around them and supporting tooth roots.
    • Tongue: A muscular organ in the mouth essential for tasting, swallowing, and speaking; it is covered with taste buds.
    • Lips: External boundaries of the mouth, aiding in speech and the prevention of food loss.
    • Hard Palate: The bony top part of the mouth that separates the oral cavity from the nasal cavity.
    • Soft Palate: The soft tissue at the back of the roof of the mouth, which helps close off the nasal passages during swallowing.
    • Uvula: A small fleshy extension at the back of the soft palate that plays a role in speech and the gag reflex.
  • Esophagus
    • A muscular tube connecting the throat (pharynx) with the stomach, facilitating the passage of food via peristaltic movement.
  • Liver and Gallbladder Anatomy
    • Liver: Key organ for metabolism and detoxification, producing bile essential for digestion and processing nutrients from food.
    • Gallbladder: A small organ that stores and concentrates bile produced by the liver, releasing it into the duodenum to aid in fat digestion.
    • Ducts:
    • Hepatic Duct: Carries bile from the liver to the gallbladder.
    • Cystic Duct: Leads from the gallbladder to the common bile duct.
    • Common Bile Duct: Merges with the pancreatic duct and enters the duodenum, responsible for delivering bile and pancreatic juice to aid digestion.
  • Sphincters in Digestive Tract
    • Pyloric Sphincter: Regulates the passage of food from the stomach to the duodenum, preventing backflow.
    • Cardiac Sphincter: Where the esophagus enters the stomach, preventing reflux of stomach contents.
    • Ileocecal Valve: Controls the flow from the small intestine (ileum) to the large intestine (cecum), preventing backflow.
  • Small Intestine
    • Duodenum: The first section of the small intestine, where digestion from the stomach continues with contributions from pancreatic enzymes and bile.
    • Ducts in the Duodenum:
    • The bile duct and pancreatic duct connect here, allowing the secretion of bile and enzymes necessary for digestion to enter the intestinal lumen.
  • Large Intestine
    • Regions:
    • Cecum: Beginning of the large intestine; absorbs fluids and salts that remain after digestion.
    • Ascending Colon: First part of the colon, going upward on the right side of the abdomen.
    • Transverse Colon: Crosses the abdomen from right to left, playing a role in the absorption of water and salts.
    • Descending Colon: Moves downward on the left side, leading to the sigmoid colon.
    • Sigmoid Colon: S-shaped section before the rectum, where feces are stored before elimination.
    • Rectum: Final segment before the anus, acting as a temporary storage site for feces.
    • Anus: The opening at the end of the digestive tract through which feces is expelled.
    • Features:
    • Hepatic Flexure: Bend between the ascending and transverse colon, an important anatomical landmark.
    • Splenic Flexure: Bend between the transverse and descending colon, named for its proximity to the spleen.
    • Epiploic Appendages: Pouches of fat along the colon that may serve to reduce friction during digestive movements.
  • Pancreas
    • Regions:
    • Head: The wider end near the duodenum, where digestive enzymes are produced.
    • Body: The central part of the pancreas where insulin and glucagon are produced.
    • Tail: The narrow end of the pancreas that extends towards the spleen.
    • Ducts:
    • Pancreatic Duct: Main duct transporting digestive enzymes to the duodenum, critical for digestion.
    • Accessory Duct: Smaller duct branching off that aids in enzyme delivery.
  • Digestive Model Considerations
    • Models will cover anatomical structures such as the gastric regions: cardiac, fundus, body, pyloric region, and associated curvatures (greater and lesser).
  • Endocrine System
    • Study content will emphasize identifying glands, hormones they secrete, and the actions of those hormones.
    • Thyroid gland Hormones:
    • Responsible for regulating metabolism and lowering serum calcium levels through the secretion of thyroid hormones.
  • Practice and Revision Tips:
    • Focus on identifying structures by their region and functions during practical exams.
    • Familiarize with models and diagrams for visual understanding of the anatomy, and engage in self-testing to