Quantity of Hb catabolised every day in a normal adult:
**Core Concept**
The question is testing the student's knowledge of erythrocyte turnover and the rate of hemoglobin (Hb) catabolism in a normal adult. Red blood cells have a lifespan of approximately 120 days, after which they are removed from the circulation and broken down by the reticuloendothelial system.
**Why the Correct Answer is Right**
In a normal adult, approximately 1-2% of red blood cells are removed from the circulation every day. This process is called erythropoietic activity or erythropoiesis. The breakdown of old red blood cells releases heme, which is then converted into bilirubin, a yellow pigment that is eventually excreted in the bile. The total amount of hemoglobin catabolized daily is roughly 250 mg/kg body weight. For a 70 kg person, this would be approximately 17.5 grams of hemoglobin.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided.
**Option B:** This option is not provided.
**Option C:** This option is not provided.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the breakdown of red blood cells is a continuous process, and the rate of erythropoiesis is tightly regulated by the hormone erythropoietin, which is produced by the kidneys in response to low oxygen levels in the blood.
**Correct Answer:** C. 17.5 grams.