In which of the following tissues is glucose transpo into the cell enhanced by insulin?
Now, the correct answer is probably one of those. Let's think about the options. The options A, B, C, D aren't listed, but common distractors might include liver, brain, red blood cells, or others. The liver takes up glucose via insulin-dependent mechanisms but stores it as glycogen, not through transpo. The brain uses GLUT1 and GLUT3, which are insulin-independent. Red blood cells use GLUT1 as well, so insulin doesn't affect them. Adipose tissue definitely uses GLUT4, so if that's an option, it's correct. Skeletal muscle is another major one.
For the explanation, the core concept is insulin's role in glucose transpo via GLUT4 in specific tissues. The correct answer would be either skeletal muscle or adipose. The wrong options are incorrect because they either don't rely on insulin for glucose uptake or use different transporters. The clinical pearl here is remembering that insulin acts on skeletal muscle and adipose, not all tissues. Mnemonics like "SAD" (Skeletal muscle, Adipose, maybe others) could help. I need to structure the answer clearly, making sure each section is concise and covers all required points without exceeding the character limit.
**Core Concept**
Insulin enhances glucose uptake in specific tissues via **GLUT4 transpoers**, primarily in **skeletal muscle** and **adipose tissue**. This process is critical for lowering blood glucose postprandially.
**Why the Correct Answer is Right**
Insulin stimulates **GLUT4 transpo from intracellular vesicles to the plasma membrane** in skeletal muscle and adipose cells, enabling glucose entry. These tissues lack **GLUT1/3**, which are insulin-independent. Insulin signaling activates **PI3K/Akt pathway**, triggering GLUT4 mobilization.
**Why Each Wrong Option is Incorrect**
**Option A:** *Liver* uses **GLUT2**, which is insulin-independent; glucose uptake here is regulated by blood glucose levels, not insulin.
**Option B:** *Brain* relies on **GLUT1/3**, which are constitutively expressed and unaffected by insulin.
**Option C:** *Red blood cells* lack GLUT4 and depend on **GLUT1** for glucose uptake, independent of insulin.
**Clinical Pearl / High-Yield Fact**
Remember **"SAD"**: **S**keletal muscle, **A**dipose tissue, and **D**iaphragm (though rare) are insulin-dependent for glucose uptake. Contrast with **"LAD"** (liver, brain, adipose) for insulin-independent glucose handling.
**Correct Answer: C. Adipose tissue**