Mechanism involved in the absorption of glucose from small intestine is which of the following:March 2005
## Core Concept
The absorption of glucose from the small intestine involves a specific transport mechanism that facilitates its uptake into the intestinal epithelial cells and subsequently into the bloodstream. This process is crucial for glucose homeostasis in the body. The primary mechanism involves the cotransport of glucose with sodium ions.
## Why the Correct Answer is Right
The correct answer, **Sodium-glucose cotransport**, is right because glucose absorption in the small intestine primarily occurs through a sodium-glucose cotransporter 1 (SGLT1) mechanism. This mechanism involves the simultaneous transport of one sodium ion and one glucose molecule into the intestinal epithelial cells. The energy for this process is indirectly provided by the sodium gradient across the intestinal epithelial cells, which is maintained by the sodium-potassium ATPase pump. This cotransport mechanism is essential for the efficient absorption of glucose from the intestinal lumen.
## Why Each Wrong Option is Incorrect
- **Option A:** Facilitated diffusion is incorrect because, while it is a method of transport across cell membranes, it does not involve the cotransport of ions like sodium and is not the primary mechanism for glucose absorption in the small intestine.
- **Option B:** Simple diffusion is incorrect because glucose is a polar molecule that cannot diffuse directly through the lipid bilayer of cell membranes without the assistance of transport proteins.
- **Option D:** Endocytosis is incorrect because it is a process of bulk uptake of substances into cells through vesicle formation, which is not the primary mechanism for glucose absorption.
## Clinical Pearl / High-Yield Fact
A key point to remember is that the sodium-glucose cotransport mechanism can be inhibited by certain drugs, such as **phlorizin**, which has been used experimentally to reduce glucose reabsorption in the kidneys. Additionally, understanding this mechanism is crucial for managing conditions like diabetes, where glucose absorption and utilization are impaired.
## Correct Answer: . Sodium-glucose cotransport