Biology Class: Digestive System Overview

Instructor

• Miss Angler

Topics Covered

• Digestive system overview
• Focus: Mouth to Stomach
• Processes: Ingestion, Digestion, Absorption, Assimilation, Egestion

Resources

• Additional video on absorption available
• Study guide: "The Cheat Sheet" for Grade 11 in English and Afrikaans

Digestive System Processes

Ingestion

• Mouth: Entry point for food
  • Involves teeth, tongue, and saliva
  • Begins mechanical and chemical digestion

Digestion Types

• Mechanical Digestion
  • Occurs in the mouth and stomach
• Chemical Digestion
  • Occurs in the mouth, stomach, and duodenum (small intestine)

Absorption

• Takes place in the small intestines
• Each nutrient follows its own pathway into the blood

Assimilation

• Nutrients become part of body tissues

Egestion

• Removal of undigested food via defecation
• Not to be confused with metabolic waste

Ingestion: Teeth Structure

• Total: 32 adult teeth (including wisdom teeth)
  • Incisors: 4 cutting teeth at front
  • Canines: 4 tearing teeth, reduced in humans
  • Premolars: 8 smaller grinding teeth
  • Molars: 8 main grinding teeth, including wisdom teeth

Functions of Teeth

• Break down food into smaller pieces
• Increase surface area for enzymes

Mouth and Accessory Structures

Salivary Glands

• Parotid Gland: Largest, behind ears
• Sublingual Gland: Under the tongue
• Submandibular Gland: In the lower jaw

Tongue

• Mixes and moves food
• Forms food into a bolus for swallowing

Throat Structures

• Pharynx: Pathway for food into esophagus
• Epiglottis: Flap preventing food from entering airways

Esophagus

• Made of smooth muscle
• Moves food via peristalsis (wave-like contractions)
• Lined with goblet cells secreting mucus

Stomach

• Food enters through the cardiac sphincter
• Two main roles: Mechanical and Chemical digestion

Digestion in the Stomach

• Mechanical Digestion: Churning and mixing
• Chemical Digestion: Breakdown into monomers
• Triggered by hormone gastrin

Gastric Juices

• Hydrochloric Acid (HCL): Breaks down proteins, kills pathogens
• Enzymes: Operate in acidic pH
• Mucus: Protects stomach lining, adds moisture

Final Product: Chyme

• Mixture of food bolus and gastric juices

Terminology Recap

• Teeth: Incisors, Canines, Premolars, Molars
• Salivary Glands: Parotid, Sublingual, Submandibular
• Esophagus: Peristalsis, Cardiac and Pyloric Sphincters
• Stomach: Gastrin, Gastric juice (HCL, enzymes, mucus), Bolus, Chyme
• Pharynx and Epiglottis: Food passage control
• Goblet Cells: Mucus secretion in esophagus and stomach

Additional Notes

• Video posting schedule: Tuesdays and Thursdays
• Encouragement to use flashcards for terminology

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Remember to review these notes regularly and practice the terminology to enhance understanding and memorization.