Small Intestine: The Absorption Specialist
Part of The Human Digestive System — GCSE Biology
This deep dive covers Small Intestine: The Absorption Specialist within The Human Digestive System for GCSE Biology. Structure and function of digestive organs, mechanical and chemical digestion, enzymes, absorption, and practical investigations It is section 5 of 15 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 5 of 15
Practice
19 questions
Recall
24 flashcards
Small Intestine: The Absorption Specialist
The small intestine is where most digestion is completed and absorption occurs. Its structure is a perfect example of adaptation for function:
Surface Area Adaptations
Three levels of surface area increase:
- Folds: The intestine wall is folded to increase surface area
- Villi: Finger-like projections cover the folds (visible to naked eye)
- Microvilli: Tiny projections on each villus cell (microscopic)
Result: Surface area increases from ~0.4m² to ~200m² - that's the size of a tennis court!
Villus Structure and Function
Functions in the Small Intestine
- Chemical Digestion: Pancreatic enzymes complete breakdown of proteins, fats, and carbohydrates
- Absorption: Nutrients pass through the villus wall into blood capillaries
- Fat Transport: Fats enter lacteals (lymph vessels) before reaching blood
- Enzyme Action: This is where many enzymes from topic 10 do their work!