Bone Marrow Dynamics, Microscopic Anatomy, and Skeletal Cytology

Practice flashcards covering bone marrow distribution, bone marrow transplantation procedures, and the four main cell types of bone connective tissue.

How does the distribution of red bone marrow differ between children and adults?

In children, red bone marrow is widely distributed throughout the spongy bone of most bones and the medullary cavity of long bones. In adults, red bone marrow is restricted to selected parts of the axial skeleton and two specific locations in the appendicular skeleton.

What cellular changes occur when red bone marrow undergoes progressive change into yellow bone marrow?

Within the medullary cavities of long bones and the inner core of most epiphyses, there is a decrease in developing blood cells and an increase in adipocytes, forming fatty yellow bone marrow.

Which specific bones in the adult axial skeleton contain red bone marrow?

The flat bones of the skull, the vertebrae, the ribs, the sternum, and the hip bones (ossa coxae).

What are the only two general locations in the adult appendicular skeleton where red bone marrow is found?

The proximal epiphyses of each humerus and femur.

How can severe anemia affect yellow bone marrow in adults?

Severe anemia—a condition with lower than normal erythrocyte numbers resulting in insufficient oxygen reaching body cells—may trigger the conversion of yellow bone marrow back to red bone marrow to produce additional erythrocytes.

What is the formal alternative term for bone connective tissue, and what does its root word mean?

It is called osseous connective tissue, where the root $\text{os}$ means bone.

From which body sites is donor red bone marrow harvested for a bone marrow transplant?

Donor red bone marrow is most commonly harvested from the hip bone and, less commonly, from the sternum.

How is a recipient prepared for a bone marrow transplant, and how are the donor cells introduced?

The recipient's red bone marrow is destroyed by high doses of chemotherapy and sometimes radiotherapy. Harvested donor cells are then injected into the recipient's vein, traveling through the blood to typical red bone marrow locations.

What two biological criteria must be matched between a donor and a recipient for a bone marrow transplant?

The donor and recipient must have matching blood types and a close match for MHC (Major Histocompatibility Complex) molecules to prevent immune system rejection.

What are the four types of cells found in bone connective tissue?

Osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts.

What are osteoprogenitor cells and what role do they play in skeletal cytology?

Osteoprogenitor cells are adult stem cells specific to the skeletal system that develop into osteoblasts.

What is the main function of osteoblasts, and what can they differentiate into?

Osteoblasts form the bone matrix, and some differentiate into osteocytes.

What is the primary function of osteocytes?

Osteocytes maintain the bone matrix.

How do osteoclasts originate and what structural features characterize them during bone resorption?

Osteoclasts form from fusing bone marrow cells. They are multinucleated cells featuring lysosomes, a ruffled border against the endosteum, and sit within a resorption lacuna while resorbing bone.