Summary
Absorption is the process where nutrients and water from digested food are transported into the blood and lymph systems. The small intestine is the primary site for nutrient absorption, while both the small intestine and colon absorb water, with the small intestine absorbing the majority.
- Small Intestine — the region where nutrients are absorbed. Example: Glucose and amino acids are absorbed into the blood here.
- Villi — small, finger-like projections that increase the surface area of the small intestine. Example: Villi have thin walls and are rich in blood capillaries for nutrient absorption.
- Microvilli — tiny hair-like structures on the villi that further increase surface area. Example: Microvilli enhance the efficiency of absorption.
- Capillaries — small blood vessels in villi that transport absorbed nutrients. Example: They carry glucose and amino acids into the bloodstream.
- Lacteals — lymphatic vessels in villi that absorb fats. Example: Lacteals transport glycerol and fatty acids into the lymphatic system.
Exam Tips
Key Definitions to Remember
- Absorption: The transport of nutrients and water from digested food into the blood and lymph.
- Villi: Finger-like projections in the small intestine that increase surface area for absorption.
- Lacteals: Lymphatic vessels in the villi that absorb fats.
Common Confusions
- Confusing the roles of capillaries and lacteals in nutrient transport.
- Misunderstanding the difference between villi and microvilli.
Typical Exam Questions
- What is the primary site of nutrient absorption in the human body? The small intestine.
- How do villi and microvilli aid in absorption? They increase the surface area of the small intestine, enhancing absorption efficiency.
- What is the role of lacteals in the villi? They absorb glycerol and fatty acids into the lymphatic system.
What Examiners Usually Test
- The relationship between the structure of villi and their function in absorption.
- The differences in absorption roles between the small intestine and the colon.