Anatomy and Physiology II Practice Test 2026 - Free Anatomy Practice Questions and Study Guide

The life span of a typical red blood cell is approximately 120 days. This duration is key to the function and physiology of red blood cells, which are responsible for transporting oxygen from the lungs to the tissues and facilitating the return of carbon dioxide from the tissues back to the lungs.

After about four months (or 120 days) of circulation in the bloodstream, red blood cells undergo age-related changes that make them less effective at their critical functions. They are typically removed from circulation by the spleen and liver, where macrophages phagocytize these older cells. The production of new red blood cells in the bone marrow occurs continuously to maintain healthy oxygen levels in the body.

This lifespan is influenced by numerous factors, including the body’s demand for oxygen and the condition of the circulatory system. Understanding this time frame helps in recognizing the dynamics of red blood cell production and destruction in maintaining homeostasis in the body.