Glucose and amino acids absorbed in a villus enter blood capillaries. Much of the fat absorbed after digestion is processed in the intestinal cells and enters the lacteal in lipid particles. Follow the nutrient named in the question before describing its route.
The 2027 SEC G3 Biology K325 syllabus links villus structure to absorption and includes the role of the hepatic portal vein. This guide connects the thin surface, the capillaries and the lacteal to their different jobs.
- Identify the named nutrient or digestion product.
- Link a thin surface to a short movement distance.
- Use the blood route for glucose and amino acids.
- Use the lacteal route for most absorbed dietary fat.
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Match each structure to its job
Villi increase the surface area available for absorption. Their thin epithelial layer gives absorbed substances a short route across the intestinal lining.
Blood capillaries carry away absorbed water-soluble nutrients. Blood flow helps maintain a concentration difference for substances moving by diffusion. The hepatic portal vein carries nutrient-rich blood from the small intestine to the liver.
A lacteal is a lymph vessel inside the villus. It takes up much of the absorbed fat after intestinal cells package it into lipid particles. Those particles later reach the bloodstream via lymph.
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Worked example | Trace glucose and dietary fat
An exam diagram labels a vessel network near the surface of a villus and a central lacteal. Explain which structure carries absorbed glucose and which takes up most fat from a meal.
| Substance | First route from the villus lining | Next destination or system |
|---|---|---|
| Glucose or amino acids | Blood capillaries | Hepatic portal circulation to the liver |
| Most absorbed dietary fat | Lacteal | Lymph before entering the bloodstream |
Glucose enters the capillary network and travels in blood towards the liver. Most dietary fat follows a different initial route through the lacteal. Giving each route separately keeps the explanation clear.
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Practise explaining one adaptation
If the question asks why the villus has a thin lining, name the short distance over which substances move. If it asks why there are many villi, name the larger surface available for absorption.
If a question specifies glucose uptake against its concentration gradient, explain that the uptake requires energy and involves active transport. The question about the subsequent blood route is a separate step.
Connect the structure to the effect rather than listing features. For example, capillary blood flow removes absorbed glucose, which can help maintain a gradient for diffusion where that process applies.
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Frequently asked questions
Is a lacteal a blood capillary?
It is part of the lymphatic system.
Does every absorbed fat component take the same route?
The lacteal is the main route for most dietary fats. Some smaller fat digestion products can enter the blood directly.
How does absorption differ from digestion?
Digestion breaks food into smaller substances. Absorption moves those substances across the intestinal lining.
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