Bone Marrow

Bone marrow performs several critical functions for blood and immune health:

• Hematopoiesis: Produces red blood cells (carry oxygen), white blood cells (fight infection), and platelets (clot blood)
• Immune Cell Development: Generates B-cells and precursor cells for T-cells
• Stem Cell Reservoir: Houses hematopoietic stem cells capable of differentiating into all blood cell types
• Support for Healing: Provides cells essential for repair and immune defense
• Storage: Stores fat and nutrients that support hematopoietic function

Key Takeaway

Bone marrow is the body’s blood cell factory, producing cells critical for oxygen transport, immune defense, and tissue repair, making it a cornerstone of circulatory and immune system health.

Basic Structure

• Two types: Red marrow (hematopoietic) and Yellow marrow (fat storage)
• Found in the medullary cavities of long bones (femur, humerus) and in flat bones (sternum, pelvis)
• Contains a microenvironment of stromal cells, blood vessels, and supportive tissue

Major Regions

• Red Marrow: Active blood cell production, rich in hematopoietic stem cells
• Yellow Marrow: Stores fat, can convert back to red marrow if needed
• Sinusoids: Specialized blood vessels for cell release into circulation

Nerves & Blood Supply

• Rich vascular supply from nutrient arteries and veins
• Innervation: Sympathetic fibers regulate blood flow and cell mobilization

Key Takeaway

Bone marrow’s structure allows it to efficiently produce, mature, and release blood cells while supporting immune system development and responding to physiological needs.

• Adult humans have about 2.6 kg of bone marrow
• Bone marrow produces millions of blood cells every second
• Hematopoietic stem cells can be harvested for transplant to treat blood disorders
• Yellow marrow increases with age, reducing red marrow activity in certain bones
• Bone marrow transplantation can restore immune and blood function in diseased or damaged individuals

• Leukemia: Cancer of bone marrow leading to abnormal white blood cell proliferation
• Aplastic Anemia: Failure to produce sufficient blood cells
• Myelodysplastic Syndromes: Ineffective blood cell production
• Multiple Myeloma: Cancer of plasma cells in bone marrow
• Bone Marrow Suppression: Caused by chemotherapy, radiation, or infections

• Fatigue or shortness of breath (low red blood cells)
• Frequent infections (low white blood cells)
• Easy bruising or bleeding (low platelets)
• Anemia or pale skin
• Slow wound healing

Source: Study.com