Glucose is primarily absorbed from
**Core Concept**
Glucose absorption in the small intestine is a crucial process for energy homeostasis. The small intestine is specialized for nutrient absorption, with the majority of glucose being absorbed in the proximal jejunum.
**Why the Correct Answer is Right**
Glucose absorption occurs through a sodium-glucose cotransporter 1 (SGLT1) mechanism. This cotransporter is a secondary active transporter that uses the sodium gradient established by the sodium-potassium pump to drive glucose uptake into the intestinal epithelial cells. Once inside the cells, glucose can be either stored as glycogen or released into the bloodstream. The SGLT1 transporter is highly specific for glucose and has a high affinity for its substrate.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the stomach is primarily involved in mechanical digestion and initial breakdown of food, rather than nutrient absorption.
**Option B:** This option is incorrect because while the pancreas does play a role in glucose metabolism through the release of insulin and glucagon, it is not directly involved in glucose absorption in the small intestine.
**Option C:** This option is incorrect because the liver plays a role in glucose storage and metabolism, but it is not the primary site of glucose absorption.
**Clinical Pearl / High-Yield Fact**
The SGLT1 transporter has a high affinity for glucose, allowing for efficient absorption even at low glucose concentrations.
**Correct Answer: C. Proximal jejunum.**