IMMUNOLOGY

Detailed explanation-1: -Normal human red blood cells have an average life span of about 120 days in the circulation after which they are engulfed by macrophages. This is an extremely efficient process as macrophages phagocytose about 5 million erythrocytes every second without any significant release of hemoglobin in the circulation.

Detailed explanation-2: -As they mature in the bone marrow, they also lose their nucleus and organelles in order to increase space for oxygen. Due to this loss of a nucleus and other organelles, blood cells cannot repair themselves when damaged; this limits their lifespan to about 120 days.

Detailed explanation-3: -Unlike most other eukaryotic cells, mature red blood cells don’t have nuclei. When they enter the bloodstream for the first time, they eject their nuclei and organelles, so they can carry more hemoglobin, and thus, more oxygen. Each red blood cell has a life span of around 100–120 days.

Detailed explanation-4: -Red blood cells (erythrocytes) The lifespan of a red blood cell is around 120 days.