Describe the structure and function of the small intestine in relation to absorption of nutrients for energy during movement. (5 marks)
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- Structure: The small intestine is a narrow tube about 6-7 metres long.
- It consists of the duodenum, jejunum, and ileum working together to absorb nutrients.
- Surface area features: The inner surface has tiny finger-like projections called villi.
- These greatly increase the surface area for nutrient absorption.
- Each villus has even smaller projections that help capture nutrients.
- Carbohydrate absorption: The digestive system breaks carbohydrates into simple sugars in the small intestine.
- These sugars pass through the intestinal wall into blood vessels.
- The absorbed glucose travels to muscles, providing the main energy source for movement during exercise.
- Protein absorption: Proteins break down into amino acids.
- These absorb through the intestinal walls for muscle repair after exercise.
- Fat absorption: Fats break down into smaller molecules that enter special vessels before reaching the bloodstream.
- During long exercise sessions, these absorbed fats provide backup energy when carbohydrate stores run low.
- Overall function: The small intestine’s structure perfectly supports its role in fuelling movement.
- Without proper absorption here, muscles cannot get the energy they need.
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Sample Answer
- Structure: The small intestine is a narrow tube about 6-7 metres long.
- It consists of the duodenum, jejunum, and ileum working together to absorb nutrients.
- Surface area features: The inner surface has tiny finger-like projections called villi.
- These greatly increase the surface area for nutrient absorption.
- Each villus has even smaller projections that help capture nutrients.
- Carbohydrate absorption: The digestive system breaks carbohydrates into simple sugars in the small intestine.
- These sugars pass through the intestinal wall into blood vessels.
- The absorbed glucose travels to muscles, providing the main energy source for movement during exercise.
- Protein absorption: Proteins break down into amino acids.
- These absorb through the intestinal walls for muscle repair after exercise.
- Fat absorption: Fats break down into smaller molecules that enter special vessels before reaching the bloodstream.
- During long exercise sessions, these absorbed fats provide backup energy when carbohydrate stores run low.
- Overall function: The small intestine’s structure perfectly supports its role in fuelling movement.
- Without proper absorption here, muscles cannot get the energy they need.