Erythropoiesis, hematopoiesis, leukopoiesis, thrombopoiesis Flashcards
Where is bone marrow found in adults?
Bone marrow is found within the trabeculae or spongy bone of flat bones and ends of long bones
* Ex: pelvis, femur
Three components of bone marrow
- Hematopoietic tissue: gives rise to all blood cells
- Sinusoids: connect arterial and venous circulation
- Stroma: support and structure layer
We lose about _ % of our bone marrow each decade that we age until age 70 when we reach an all time low of _
We lose about 10% of our bone marrow each decade that we age until age 70 when we reach an all time low of 70%
What cells are found in the stroma of the bone marrow?
- Fibroblasts
- Macrophages
- Adipose cells
- Osteogenic cells
Collagen and reticular fibers also provide a nice scaffording
Which cell lineage makes up the largest percent in the bone marrow?
Neutrophils make up the largest percentage in the bone marrow
* Other granulocytes are present in much smaller numbers (eosinophils and basophils)
The second largest cell lineage in the bone marrow is _
The second largest cell lineage in the bone marrow is erythroid series
The typical myeloid: erythroid ratio is _
The typical myeloid: erythroid ratio is between 2:1- 4:1
* This represents neutrophils: red cells
_ is the process of making red blood cells
Erythropoiesis is the process of making red blood cells
Fetal erythropoiesis begins in the _ at approximately 3 weeks of gestation
Fetal erythropoiesis begins in the yolk sac at approximately 3 weeks of gestation
* Yolk sac –> liver –> spleen –> bone marrow
What is the order of erythropoiesis sites
Young Liver Synthesizes Blood: Yolk sac, Liver, Spleen, Bone marrow
Six stages/ cells of erythropoiesis
- Proerythroblast: large, fine chromatin, basophilic cytoplasm, prominent nucleoli
- Basophilic erythroblast: deep blue from free ribosomes
- Polychromatophilic erythroblasts: hint of pink from hemoglobin production
- Orthochromatophilic erythroblast: nucleus is dense, dark, small
- Reticulocyte: light purple cytoplasm, nucleus extruded
- Erythrocyte: all RNA leaves –> become pink and disk shaped
Describe the changes that can be seen from proerythroblast –> erythrocyte
- Cell gets smaller in size
- Cytoplasm turns from deep blue –> red
- Nucleus shrinks and gets darker
- Chromatin becomes condensed
How does oxygen demand stimulate erythropoiesis?
Low oxygen –> stimulates the kidneys via hypoxia-inducible factor –> kidney secretes erythropoietin (EPO) –> stimulates the bone marrow to make more erythrocytes
The liver, like most other organs of the gut, originates from the _
The liver, like most other organs of the gut, originates from the endoderm
The spleen is derived from the _
The spleen is derived from the mesoderm (from the dorsal mesogastrium)
The skeletal bones arise from the _ while the bones of the head/face arise from the _
The skeletal bones arise from the mesoderm while the bones of the head/face arise from the neural crest
Intramembranous ossification involves bone that is formed directly from _
Intramembranous ossification involves bone that is formed directly from mesenchymal tissue
* Mesenchymal cells –> osteoblasts –> osteoid –> hard bone
* This is the process used for flat bones like the skull
Cell differentiation vs maturation:
Cell differentiation is the process by which cells decide which cell line to be; cell maturation is the movement through stages
The three main hematopoietic cell lines are:
The three main hematopoietic cell lines are:
1. Red blood cells (erythrocytes)
2. White blood cells (leukocytes)
3. Platelets
All hematopoietic cells come from the bone marrow where they start as uncommitted stem cells –> give rise to _ or _
All hematopoietic cells come from the bone marrow where they start as uncommitted stem cells –> give rise to lymphoid stem cell or myeloid stem cell
All leukocytes (granulocytes and agranulocytes) have granules but only the granulocyte have specific granules; these cells are _ , _ and _
All leukocytes (granulocytes and agranulocytes) have granules but only the granulocyte have specific granules; these cells are neutrophils , eosinophils, and basophils
* The agranulocytes are the monocytes and lymphocytes
Six stages of neutrophil maturation
- Myeloblast: fine chromatin
- Promyelocyte: very large, deep purple granules
- Myelocyte: more condensed chromatin, specific granules which are pale pink
- Metamyelocyte: more condensed chromatin, horseshoe nucleus
- Band: nucleus thins and looks like U
- Segmented neutrophil
3 steps of monocyte maturation
- Monoblasts: very large, indented nucleus, tiny granules
- Promonocyte: “tissue-paper” nuclei
- Monocyte: kidney bean nucleus, chromatin has raked pattern
Promonocyte
The lymphoid series (B cells, T cells, NK cells) have a simple maturation from _ to _
The lymphoid series (B cells, T cells, NK cells) have a simple maturation from lymphoblasts to lymphocytes
Thrombopoiesis is the process of making _
Thrombopoiesis is the process of making thrombocytes (aka platelets)
Platelets are really just fragments of cytoplasm derived from giant bone marrow cells called _
Platelets are really just fragments of cytoplasm derived from giant bone marrow cells called megakaryocytes
Megakaryocyte
What is unique about megakaryoctyes that makes them so large in size?
Megakaryocytes undergo endomitosis whereby they experience chromosomal replication that does not involve nuclear division
* Small pockets of cytoplasm are formed in the cell and platelets are held until they are released into cytoplasm
Megakaryocytes are derived from _ cells
Megakaryocytes are derived from common myeloid progenitor cells
What are the stages of megakaryocyte progression?
Stem cell –> megakaryoblast –> promegakaryocyte –> megakaryocyte
The major signaling molecule that stimulates growth and development of megakaryocytes is _
The major signaling molecule that stimulates growth and development of megakaryocytes is thrombopoietin
Thrombopoietin is secreted constituitively by the _ and will increase when platelets decrease and will decrease when platelets increase such that the _ of platelets is constant
Thrombopoietin is secreted constituitively by the liver and will increase when platelets decrease and will decrease when platelets increase such that the mass of platelets is constant
Megakaryocytes are found in the _
Megakaryocytes are found in the sinusoids of the bone marrow
Megakaryocytes must be _ to produce platelets; once platelets are formed they either fracture or separate from the megakaryocyte
Megakaryocytes must be hyperdiploid to produce platelets; once platelets are formed they either fracture or separate from the megakaryocyte
