Your immune system is complex. You might already know your digestive system holds up to 80% of your immune cells, but did you know that even your thigh bones are instrumental in immunity? It's true. In fact, bone marrow in the thigh bones, as well as other bones, produces cells which develop into a variety of immune cells.
Most of us understand that overall health depends on your immune system, and that a healthy immune system begins in the gastrointestinal tract—making the intestinal tract part of the body’s first line of defense. Other important parts of the immune system, however, include the skin, the stomach, the pancreas, the spleen, the liver, the thymus gland, the lymphatic system and—you guessed it—bone marrow.
Bone marrow is the spongy tissue inside some of your bones, including your hip and thigh bones. There are two kinds of bone marrow found in bones: yellow marrow and red marrow. Yellow marrow dominates as people age and its primary function is to store fat. Red marrow, on the other hand, is predominant in the young. There is a caveat to this, though. Interestingly, if you lack red bone marrow for any reason, your body has the ability to convert yellow bone marrow back into red bone marrow.
In adults, most red bone marrow is found in the spongy bone of the skull, the ribs, the breastbone, the collarbone, the vertebrae and the hip and thigh bones. Red bone marrow is essential to the manufacturing of new blood cells—including red blood cells, white blood cells and platelets.
Here’s how red bone marrow makes those necessary new blood cells: Red bone marrow contains young cells—called stem cells—which can develop into red blood cells, white blood cells or platelets, depending on the body’s need.
Red blood cells make up almost half of the blood and pick up and carry oxygen throughout the body. White blood cells are necessary to attack and fight off germs and other invaders causing infections. There are a variety of white blood cells, too, and each kind fights off different invaders. Platelets, also known as thrombocytes, are small cellular pieces that serve to assist with proper blood clotting to stop excessive bleeding.
The bottom line is that the white blood cells made in the red bone marrow are essential to a healthy immune system. In short, white blood cells are continually combing the body, ready to rush in and dismantle invading germs or bacteria. And while white blood cells typically have a short life cycle of only a few days to a few weeks, their presence and fighting power can make the difference between health and unhealth.
I guess we can chalk another one up for the importance of strong, healthy bones.