Hematopoiesis Flashcards
What bones are used in blood cell synthesis?
Skull, ribs, sternum, vertebrae, pelvis, proximal femurs
All cells are derived from a single […] stem cell.
Pluripotent hematopoietic
What are the two cells that directly arise from a hematopoietic stem cell (HSC)?
Common myeloid progenitor (CMP) and common lymphoid progenitor (CLP)
Define three lineages to produce multiple cell types
- Granulocyte monocyte progenitor
- Megakaryocyte progenitor
- Common lymphoid progenitor
What are the 3 phases of hematopoiesis in embryonic development?
- Starts in fetus during 1st trimester where we get the development of hematopoietic islands in the umbilical vesicle
- Continues after 2nd trimester in liver and then in spleen
- During the 7th month, the bone marrow becomes the primary site of hematopoiesis.
What does bone marrow consist of?
Blood vessels, hematopoietic cells, and sinusoids
Define sinusoids
Unique vascular unit with an endothelial lining, discontinuous basement membrane (open and porous), and an incomplete covering of adventitial cells
Define adventitial cells
They provide support for developing blood cells via producing reticular fibers and cytokine secretion
What is between the sinusoids and the actual bone marrow tissue that is functionally active?
Hematopoietic cords which contain HSCs
4 steps of cell migration across the bone marrow endothelium
- Maturing blood cell or megakaryocyte process pushes against an endothelial cell
- Will fuse and pierce luminal plasma membrane
- Each blood cell/process must squeeze through the aperture and enter sinusoidal lumen
- Endothelial cells repairs itself and aperture disappears
What type of bone contains bone marrow?
Spongy bone
Where is red bone marrow located
Within medullary cavity of young long bones and spaces of spongy bone
What is yellow bone marrow composed of, and where is it found?
Predominantly composed of adipose cells, and is found in medullary cavity of adult bones which are no longer hematopoietically active
How do you calculate normal cellularity of bone marrow?
Subtract individuals age from 100 and then ± 10%
What does cellularity of bone marrow represent?
Represents ratio of HSCs to adipocytes
Define hypocellular marrow.
What can cause this?
Small number of HSCs.
Caused by aplastic anemia and chemotherapy
Define hypercellular marrow.
What can cause this?
This is bone marrow affected by HSC tumors.
Caused by acute myelogenous leukemia