Hematopoiesis and Bone Marrow Flashcards
How long do RBCs live? Thrombocytes?
RBC= 120 days thrombocytes= 10 days
Where does hematopoiesis begin in development?
In the blood islands of the yolk sac.
Major hematopoiesis site in the second trimester? Where does it also start during the second trimester? What organ plays a minor role during this time
The liver. Also starts happening in the bone marrow during the second trimester. the spleen is also a minor site.
Where does hematopoiesis happen in adults?
in the red bone marrow (and lymph tissues)
- What are blood cells derived from?
- what role do these cells have in regeneration?
- Where can these cells be isolated in the embryo? In adults?
- The pluripotent hemopoietic stem cells (HSC), which can differentiate into all blood cell lineages.
- can contribute to non-blood cell lineages as well to regenerate tissues and organs.
- In the umbilical cord, liver, and bone marrow. In adults, they can be found bone marrow.
As far as blood cells are concerned, what do HSC cells become, and what do those two things give rise to?
- Common myeloid progenitor- becomes granulocytes, mast cells, macrophages, monocytes, megakaryocytes, dendritic cells, and erythrocytes.
- common lymphoid progenitor- natural killer cells, t cells, B cells
- What commit cells to become proerythroblasts?
2. How does it divide?
- Cytokines (EPO) and the transc. fact. GATA-1.
2. Undergoes MITOSIS
- What does a basophilic erythroblast look like?
- Nucleoli?
- how does it divide?
- Smaller than proerythroblast. Blue cytoplasm due to ribosomes making hemoglobin.
- No nucleoli.
- Undergoes mitosis.
- What does a polychromatophilic erythroblast look like?
- Nucleoli?
- How does it divide?
- Pronounced checker-board pattern. Basophilic cytoplasm, but has eosinophilic areas due to hemoglobin.
- No nucleoli
- Undergoes mitosis.
- What does a normoblast (orthochromatophilic erythroblast) look like?
- How does it divide?
- Dark, round, condensed nucleus about to get extruded. High amounts of hemoglobin makes a more eosinophilic cytoplasm.
- NO LONGER CAPABLE OF MITOSIS.
- What does a reticulocyte look like?
2. What do high numbers of it indicate?
- No nucleus. Cytoplasm is slightly basophilic compared to erythrocyte.
- High numbers indicate that the patient is experiencing blood loss.
Order of developing erythroblasts, starting from HSC.
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- HSC
- Common myeloid progenitor
- megakaryocyte/erythrocyte progenitor
- Proerythroblast
- basophilic erythroblast
- polychromatophilic erythroblast
- normoblast (orthochromatophilic erythroblast)
- reticulocyte
- erythrocyte
How are RBCs destroyed, and where? What happens to the heme and iron?
Macrophages phagocytyze old RBCs in the spleen, liver, and marrow. The heme iron is released and recycled or stored as ferritin or hemosiderin. Heme is degraded to billirubin.
How many platelets made a day? What controls their production, and where does it come from?
over a billion. GM-CSF cytokine as well as thrombopoetin, produced by liver and kidney.
Order of cells in production of thrombocytes, starting with HSC.
- HSC
- common myeloid progenitor
- megakaryocyte/erythrocyte progenitor
- megakaryocyte committed progenitor
- megakaryoblast
- megakaryocyte
- thrombocyte
What is interesting about the division of megakaryoblasts?
Does endomitosis, meaning it reproduces nuclear elements with dividing; causes ploidy of up to 64n.
What does a megakaryocyte look like? What does it have in its peripheral fields?
Complex multilobed nucleus. scattered azurophilic granules. Platelets in peripheral fields.
What is thrombocytopenia, and what does it mean for chemo?
Decreased platelets due to immune disorder or cancer. Risk of bleeding, and limits chemotherapy.
- what is the length of granulopoiesis?
2. When/where do the phases begin/end? What are they called?
- Two weeks.
- a. mitotic (proliferative phase)- occurs in first week and stops in late myelocyte.
b. post-mitotic (differentiation phase)- occurs in second week, from metamyelocyte to mature granulocyte.
How long do neutrophils live in tissue? What does the bone marrow thus do? When do their numbers increase? Special reserve is where, in addition to this?
Only 1-2 days. Marrow retains a large pool of neutrophils, and makes over a billion a day. Numbers increase during strenuous exercise, infection, inflammation. Vascular reserve also there, known as circulating pool of neutrophils.
What are the precursors in order of granulopoiesis? Include when you can differentiate between the kind of granulocyte.
- HSC
- Common myeloid progenitor
- Granulocyte/monocyte progenitor
- myeloblast
- Promyelocyte
- Myelocyte- can differentiate b/w the three granulocytes due to specific granules
- Metamyelocyte- lineages clearly identifiable by specific granules
- band/stab cell
- neutrophil (or others, but only expected to recognize neutrophil)
What does a promyelocyte look like? Nucleoli?
Round nucleus, coarse chromatin. Nucleolus present. Basophilic cytoplasm.
what does a myelocyte look like? nucleoli? golgi?
Dark blue granules in cytoplasm. Flattened nucleus, no nucleoli. Clear golgi next to nucleus.
What does a metamyelocyte look like?
Kidney bean/v shaped nucleus. cytoplasm starting to become more pink than blue due to specific granules. Pale cytoplasm, golgi in the V.
