Hematopoiesis

Question 1

Parenchyma

Answer 1

Has fat, erythroblastic islands, and granulocytic precursors.

Question 2

Erythroid Precursors

Answer 2

Outnumbered by granulocytic 3:1. Take about 7d to develop in the marrow. The reticulocyte is the least mature type seen in blood and are reticulocytes for about a day after release into the blood and last for 120 days. Example: Proerythroblast -> basophilic erythroblast -> polychromatophilic erythroblast -> orthochromatophilic erythroblast -> retuculocyte -> erythrocute.

Question 3

Granylocytic Precursors

Answer 3

Outnumber erythrocytic 3:1. Take about 14 days to develop. The least mature cell found in the blood is the band cell. Neutrophils last hours to 1 day. Example: Pluripotent stem cell -> myeloid stem cell -> progenitor cell -> Myeloblast -> Promyelocyte -> Neutrophilic myelocyte -> Nurtrophilic metamyelocyte -> neutrophil.

Question 4

Erythropeoietin

Answer 4

Produced by renal cells. Stimulates RBC development.

Question 5

GM-CSF

Answer 5

Produced by lymphocytes, endothelium, and fibroblasts. Stimulates granulocyte and macrophage development.

Question 6

G-CSF

Answer 6

Produced by macrophages, endothelium, and fibroblasts. Stimulates granulocyte development.

Question 7

IL-3

Answer 7

Produced by T-lymphocytes. Stimulates production of all myeloid cells.

Question 8

Thrombopoietin

Answer 8

Produced by liver and kidney. Stimulates production of platelets.

Question 9

Bone Marrow

Answer 9

More mature cells than blast cells. Fat in marrow increases with age. You do not see stem cells or progenitor cells in the marrow unless use cell markers (there are few of them).

Question 10

Fetal Erythroblastic

Answer 10

Found in yolk sac, liver, spleen, and bone marrow.

Question 11

Adult Erythropoiesis

Answer 11

Found in bone marrow. Medullary hematopoiesis. Liver and spleen can resume only if necessary. Extramedullary hematopoiesis. Most occurs in the vertebrae, ribs, sternum, and pelvis.

Question 12

Erythroblastic Islands

Answer 12

Macrophages. Located near sinuses.

Question 13

Megakaryocyte

Answer 13

Extend cytoplasmic processes into sinuses by dynein motors. Demarcation membranes which permit the fragmentation of platelets from the body of the Megakaryocyte directly into the marrow sinusoids.

Question 14

Platelets

Answer 14

Granules full of growth, clotting, and vasoactive substances.

Question 15

Vascular Compartment

Answer 15

Venous sinuses that course through the bone marrow. Lined by endothelium. Adventitial cells in close contact.

Question 16

Blast Cells

Answer 16

Mitotic but not self-renewing. All daughter cells go on to terminal differentiation.

Question 17

Cell Development

Answer 17

More mature characteristics as they lose potentiality while developing. Cells and nuclei shrink, nucleoli disappear, and specific features develop.

Question 18

Red vs Yellow Marrow

Answer 18

Red Marrow: Active marrow, relatively less fat, more making blood cells.

Yellow Marrow: Inactive marrow, lots of fat, ability to convert back to red in times of need.

Question 19

CFU

Answer 19

Progenitor cells that differentiate into a limited number of cell types.

Question 20

Extravascular (stroma)

Answer 20

Hematopoietic cells. Reticular fibers. Adventitial cells (stromal cells). Fat cells.