What is Blood?
Blood is a specialized connective tissue that circulates throughout the body, delivering essential substances such as oxygen and nutrients to cells and removing waste products. It consists of various components, including red blood cells (RBCs), white blood cells (WBCs), platelets, and plasma.
Red Blood Cells (Erythrocytes): These cells are responsible for the transport of oxygen from the lungs to the tissues and the return of carbon dioxide from the tissues to the lungs. They contain the protein hemoglobin, which binds oxygen.
White Blood Cells (Leukocytes): These cells are part of the immune system and are involved in protecting the body against infection and disease. They can be further classified into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).
Platelets (Thrombocytes): These are small cell fragments that play a key role in blood clotting and wound healing.
Plasma: The liquid component of blood that carries cells and a variety of substances, including nutrients, hormones, and waste products.
What is Bone Marrow?
Bone marrow is a spongy tissue found within the hollow interior of bones, particularly in the pelvis, ribs, sternum, and vertebrae. It is the primary site of new blood cell production or
hematopoiesis.
Red Bone Marrow: Active in hematopoiesis, it contains hematopoietic stem cells that can differentiate into various blood cells. It is abundant in children and found in the flat bones of adults.
Yellow Bone Marrow: Primarily composed of adipose tissue and serves as a storage for fats. It can convert back to red marrow under certain conditions, such as severe blood loss or anemia.
What is Hematopoiesis?
Hematopoiesis is the process by which all blood cells are produced in the bone marrow. It involves the differentiation and maturation of hematopoietic stem cells into various types of blood cells. This process is tightly regulated by a variety of growth factors and cytokines.
What are Hematopoietic Stem Cells?
Hematopoietic stem cells (HSCs) are multipotent stem cells that reside in the bone marrow. They have the capacity to differentiate into all types of blood cells, including erythrocytes, leukocytes, and platelets. HSCs are critical for maintaining blood cell homeostasis throughout life.
Stromal Cells: These include fibroblasts, endothelial cells, and adipocytes that provide structural support and secrete growth factors.
Macrophages: These cells phagocytose cellular debris and secrete cytokines that influence hematopoiesis.
Osteoblasts and Osteoclasts: Cells involved in bone formation and resorption, respectively, which also play a role in regulating the bone marrow niche.
Blood Smear: A drop of blood is spread thinly on a microscope slide, stained (usually with Wright or Giemsa stain), and examined under a microscope to evaluate the morphology of blood cells.
Bone Marrow Aspiration: A sample of the liquid portion of bone marrow is aspirated and examined for cellular composition and abnormalities.
Bone Marrow Biopsy: A core of bone marrow tissue is obtained, processed, and examined to assess the architecture and cellularity of the marrow.
Anemia: A condition characterized by a deficiency in red blood cells or hemoglobin, leading to fatigue and weakness.
Leukemia: A group of cancers that originate in the bone marrow and result in the overproduction of abnormal white blood cells.
Thrombocytopenia: A condition marked by a low platelet count, increasing the risk of bleeding.
Lymphoma: A type of cancer that affects the lymphatic system, which includes lymph nodes and bone marrow.
