Digestive system medium

Dental, Oral and General Anatomy

• Dental hygienists and therapists require knowledge of the digestive system for various reasons, including understanding the mouth's role as the start of the digestive tract, the impact of saliva on oral health and the consequences of saliva deficiency.

Digestion Processes

• The five main activities that occur in the digestive system are ingestion, propulsion, digestion, absorption, and elimination (defecation).
• Ingestion: The intake of food or drink.
• Propulsion: The mixing and propelling of food through the digestive tract.
• Digestion: The breakdown of food through mechanical and chemical processes.
• Absorption: The passage of digested food substances from the digestive system into the bloodstream for use by body cells.
• Elimination: The excretion of waste products from the body.

Parts of the Alimentary Canal

• The alimentary canal, also known as the digestive tract, consists of several organs:
  • Mouth: The beginning of the digestive tract where mechanical and chemical digestion begins.
  • Salivary Glands: Secrete saliva, which moistens food, aids in swallowing, and contains enzymes that initiate digestion.
  • Gall Bladder: Stores bile produced by the liver, which aids in the digestion of fats.
  • Liver: Produces bile for fat digestion, filters blood, and performs other essential functions.
  • Pancreas: Produces digestive enzymes and hormones that regulate blood sugar levels.
  • Small Intestine: The primary site of nutrient absorption, where most digestion takes place.
  • Oesophagus: A muscular tube that transports food from the mouth to the stomach.
  • Stomach: A muscular pouch that continues the mechanical and chemical breakdown of food.
  • Large Intestine (Colon): The final part of the digestive tract, responsible for absorbing water and electrolytes, storing and eliminating waste products, and producing certain vitamins.
  • Rectum: The last portion of the large intestine, where solid waste is stored before elimination through the anus.

Digestive Processes in the Mouth

• Mechanical Digestion: Teeth break down food into smaller pieces with the aid of the tongue—voluntary muscles.
• Chemical Digestion: Salivary amylase, an enzyme present in saliva, breaks down starch in food into maltose, a simpler sugar.
• Bolus Formation: Chewing and mixing with saliva create a rounded mass of food called a bolus.
• Swallowing: The soft palate and uvula move upward to close off the nasopharynx, preventing food from entering the nasal cavity.

The Stomach

• Functions:
  • Temporarily stores food for 3-4 hours.
  • Churns food into a creamy substance called chyme, a process facilitated by muscular contractions.
  • The pyloric sphincter controls the flow of chyme into the small intestine.
• Gastric Juice: Gastric glands in the stomach produce gastric juice, which contains pepsin, an enzyme that breaks down proteins, and hydrochloric acid, which makes the stomach highly acidic.
• Rugae: Folds in the stomach lining that increase surface area for better digestion and absorption.

The Small Intestine

• Functions:
  • Completes the digestion process.
  • Absorbs nutrients through villi into blood vessels and the lymphatic system.
• Segments:
  • Duodenum: The first part of the small intestine, where most digestive enzymes are secreted.
  • Jejunum: The middle part of the small intestine, where most nutrient absorption occurs.
  • Ileum: The last part of the small intestine, where the absorption of vitamin B12 and bile salts takes place.

The Large Intestine

• Functions:
  • Absorbs remaining water and electrolytes not absorbed in the small intestine.
  • Synthesizes vitamins, mainly vitamin K and some B vitamins.
  • Stores and eliminates waste products (feces).
• Characteristics:
  • Less muscular than the small intestine.
  • Contains more goblet cells, which produce mucus for lubrication.
  • Lack of villi.
  • The remaining digestive processes take about 16 hours in the large intestine.

The Rectum

• Functions:
  • Stores solid waste until it is eliminated through the anus.
  • Peristaltic waves help move the feces towards the anus.
  • Sphincter muscles (voluntary and involuntary) control the release of feces from the body.

Digestion

• Definition: The process of breaking down food into nutrients for energy, growth, and cell repair.
• Process: Food is broken down mechanically and chemically as it moves through the digestive tract.
• Chemical Breakdown: Involves enzymes that speed up the reactions involved in the breakdown of larger food molecules into smaller ones.
• Importance: The digestive tract modifies food physically and chemically, eliminating unusable waste.

Digestive Juices

• Types:
  • Gastric juice: Produced in the stomach and contains pepsin and hydrochloric acid.
  • Pancreatic juice: Produced by the pancreas and contains various digestive enzymes.
  • Bile: Produced by the liver and aids in the digestion of fats.

Digestive Enzymes

• Types:
  • Amylase: Breaks down starches into simpler sugars, such as maltose and glucose.
  • Lipase: Breaks down lipids (fats) into fatty acids and glycerol.
  • Protease: Breaks down proteins into amino acids.

Digestion of Carbohydrates

• Process:
  • Begins in the mouth with salivary amylase.
  • Pancreatic amylase continues the breakdown in the small intestine.
  • Intestinal enzymes like sucrase, maltase, and lactase break down disaccharides into monosaccharides (simple sugars).
• Steps:
  • Polysaccharide + salivary amylase → maltose + small polysaccharides.
  • Undigested polysaccharides + pancreatic amylase → maltose + disaccharides.
  • Maltose, Sucrase, Lactase→ monosaccharides.

Digestion of Proteins

• Process:
  • Begins in the stomach with the enzyme pepsin and continues in the small intestine with trypsin and chymotrypsin from pancreatic juice.
  • Breakdown products include amino acids.

Test your knowledge on the anatomy related to dental hygiene and the digestive system. This quiz covers key processes of digestion, the parts of the alimentary canal, and the importance of oral health in digestion. Perfect for dental hygienists and students in health sciences.