HEMATOPOIESIS Flashcards
one of the largest organ in the body consisting of hematopoietically active marrow and non hematopoietically active marrow
bone marrow
projections of calcified bone, forming a three-dimensional matrix resembling a honeycomb which provides structural support for developing blood cells
trabeculae
which marrow is dominant during infancy and early childhood
red marrow
when adipocytes (yellow marrow) become more abundant
between 5 and 7 years
the process of replacing the active marrow by adipocytes during development
retrogresssion
results in restriction of the active marrow in the adult to the:
sternum, vertebrae, scapulae, pelvis, ribs, skull, and proximal portion of the long bones
red marrow-to-yellow marrow ration in adults
equal amounts
is utilized when there is increased active marrow demand (i.e. excessive blood loss, or hemolysis)
yellow marrow
components of bone marrow
hematopoietic cells, stromal cells, and blood vessels
stromal cells originate from:
mesenchymal cells that migrate into the central cavity of the bone
regulates the flow of particles entering and leaving hematopoietic spaces in the vascular sinuses
endothelial cells
regulate the volume of the marrow in which active hematopoiesis occurs
adipocytes
they also secrete cytokines or growth factors that may stimulate HSC numbers and bone homeostasis
adipocytes
secrete cytokines that regulate late hematopoiesis; they are located throughout the marrow space
macrophages and lymphocytes
form an incomplete layer cd cells on the albuminal surface of the vascular sinuses
reticular adventitial cells
