Leukocytes, also known as white blood cells, and red blood cells are essential components of the bloodstream. While red blood cells carry oxygen throughout the body, leukocytes play a critical role in the immune system, protecting the body against diseases, parasites, and other pathogens. Comprising only 1% of the total blood volume, white blood cells are relatively small in number but have a powerful impact on our health. Similar to red blood cells, they are produced in the bone marrow. However, instead of circulating freely in the bloodstream, most white blood cells are stored in specialised organs such as the thymus, spleen, bone marrow, and lymph nodes until they are needed.

White blood cells are the valiant defenders of our immune system. Despite their limited presence in the bloodstream, they diligently safeguard our well-being. What's even more remarkable is that once white blood cells encounter a pathogen, they don't simply retreat when the threat subsides. They retain a few memory cells on constant alert, prepared to mount a rapid response in case of a recurring encounter with the same disease. This immunological memory enables the body to provide a faster and more efficient defense if confronted with a familiar pathogen, potentially preventing the need to endure the same illness again.