bone marrow

(noun)

The fatty vascular tissue that fills the cavities of bones; the place where new blood cells are produced.

Related Terms

Examples of bone marrow in the following topics:

  • Bone Marrow Examination

    • In patients with suspected peripheral blood or bone marrow diseases, a bone marrow biopsy can isolate bone marrow for an examination.
    • Bone marrow examination is the pathologic analysis of samples of bone marrow obtained by bone marrow biopsy and bone marrow aspiration.
    • This is the purpose of bone marrow aspiration and biopsy.
    • There are few contraindications to bone marrow examination.
    • A bone marrow biopsy procedure consists of inserting a large-gauge syringe into an area of the hip and extracting the bone marrow.

  • RBC Life Cycle

    • Erythrocytes are continuously produced in the red bone marrow of large bones at a rate of about 2 million cells per second in a healthy adult.
    • Erythrocytes differentiate from erythrotropietic bone marrow cells, a type of hemopoietic stem cell found in bone marrow.
    • Unlike mature RBCs, bone marrow cells contain a nucleus.
    • Just before and after leaving the bone marrow, the developing cells are known as reticulocytes.
    • The bilirubin is excreted through the digestive system in the form of bile, while some of the iron is released into the plasma to be recirculated back into the bone marrow by a carrier protein called transferrin. 

  • Overview of the Musculoskeletal System

    • Located in long bones are two distinctions of bone marrow: yellow and red.
    • The yellow marrow has fatty connective tissue and is found in the marrow cavity.
    • In times of starvation, the body uses the fat in yellow marrow for energy.
    • The red marrow of some bones is an important site for hematopoeisis or blood cell production that replaces cells that have been destroyed by the liver.
    • Here, all erythrocytes, platelets, and most leukocytes form in bone marrow from where they migrate to the circulation.

  • Bone

    • Compact bone (or cortical bone), forming the hard external layer of all bones, surrounds the medullary cavity (innermost part or bone marrow).
    • Compact bone tissue forms the outer layer of all bones while spongy or cancellous bone forms the inner layer of all bones.
    • Red bone marrow is found between the trabuculae.
    • The red bone marrow of the femur and the interior of other large bones, such as the ileum, forms blood cells.
    • Spongy bone reduces the density of bone, allowing the ends of long bones to compress as the result of stresses applied to the bone.

  • Gross Anatomy

    • All the bones in the body can be described as long bones or flat bones.
    • Bones of the body overall is and organ made up of bone tissue, bone marrow, blood vessels, epithelium, and nerves.
    • Cortical bone is compact bone, while cancellous bone is trabecular and spongy bone.
    • Bones of the body overall is and organ made up of bone tissue, bone marrow, blood vessels, endosteum, periosteum, and nerves.
    • The interior part of the long bone is called the medullary cavity with the inner core of the bone cavity being composed of marrow.

  • Bone Development

    • Intramembranous ossification stems from fibrous membranes in flat bones, while endochondral ossification stems from long bone cartilage.
    • The non-mineralized portion of the bone or osteoid continues to form around blood vessels, forming spongy bone.
    • Connective tissue in the matrix differentiates into red bone marrow in the fetus.
    • The spongy bone is remodeled into a thin layer of compact bone on the surface of the spongy bone.
    • Osteoclasts then break down some of the spongy bone to create a marrow, or medullary cavity, in the center of the diaphysis.

  • Microscopic Anatomy of Bone

    • The basic microscopic unit of bone is an osteon, which can be arranged into woven bone or lamellar bone.
    • Osteons can be arranged into woven bone or lamellar bone.
    • Woven bone is replaced by lamellar bone during development.
    • Lamellar bone makes up the compact or cortical bone in the skeleton, such as the long bones of the legs and arms.
    • The spaces within trabecular bone are filled with active bone marrow.

  • Bone Remodeling

    • Bone remodeling or bone turnover is the process of resorption followed by replacement of bone and occurs throughout a person's life.
    • Bone volume is determined by the rates of bone formation and bone resorption.
    • Numerous bone-derived growth factors have been isolated and classified via bone cultures.
    • Fibroblast growth factor activates various cells of the bone marrow including osteoclasts and osteoblasts.
    • Due to the over-action of osteoclastic bone resorption, the bone becomes quite fragile.

  • Bone Repair

    • The bone marrow (when present), endosteum, small blood vessels, and fibroblasts are other sources of precursor cells.
    • The next phase is the replacement of the hyaline cartilage and woven bone with lamellar bone.
    • Substitution of the woven bone with lamellar bone precedes the substitution of the hyaline cartilage with lamellar bone.
    • This new lamellar bone is in the form of trabecular bone.
    • The remodeling process continues with substituttion of the trabecular bone with compact bone.

  • Postnatal Bone Growth

    • It forms the epiphyses of long bones and the extremities of irregular and flat bones.
    • 1) Zone of reserve cartilage: This region is farthest from the marrow cavity and consists of hyaline cartilage that does not actively transform into bone.
    • 2) Zone of cell proliferation: Closer to the marrow cavity, chondrocytes in this region multiply and arrange themselves into longitudinal columns of flattened lacunae.
    • Each column then becomes a longitudinal channel that is immediately invaded by blood vessels and marrow from the marrow cavity.
    • Newly formed bonee.