Hemopoiesis Flashcards
In the second trimester Hemopoiesis occurs primarily in the developing
Liver with the spleen playing a minor role
In third trimester Hemopoiesis takes place in
Marrow of specific bones
Throughout childhood and adult life erythrocytes , granulocytes monocytes and platelets continue to form from stems cells located
In Bone marrow
Plurimptent cells
Stem cells
Stems cells proliferate forming
Progenitor cells
Progenitor cells diferenciate in two linages
Lymphoid cells
Mieloid cells
Myeloid cells includes
Granulocytes
Monocytes
Erythrocytes
Megakaryocytes
The progenitor cells for the blood cells are commonly called
Colony-forming units CFUs
Four major types of colony forming units
CFU E
CFU Meg thrombocytic lineage
CFU GM
CFU L
Progenitor and precursor cells divide more rapidly producing at
3x10^9 erythrocytes and 0.85x10^9 in human bone marrow
Hemopoiesis depends on a microenviroment or niche that are
Specific endocrine
Paracrine
Juxtacrine factors
Also call Cytokines, are glycoproteins that stimulate proliferation of progenitor and precursor cells and promote cell differentiation and maduration with specific lineages
Colony stimulating factors CSF
Each progenitor cell/CFU lineage produce
Precursor cells
Bones marrow is found in
The medullary canals of long Bones and in the small cavities of cancellous bone
Two types of Bones
Red bone marrow
Yellow bone marrow
Blood forming whose color is produce by An abundance of blood and hemopoietic cells
Red bone marrow
Bone marrow which is filled with adipocytes that excude most hematopoietic cells
Yellow bone marrow
In early embryo these blood cells arise in the
Yolk sac mesoderm
Yellow marrow reverts to red when
A sever bleeding or hipoxia
Red bone marrow contains a
reticular connective tissue ,Stroma, hemopoietic cords, or islands of cell and sinusoidal capillaries
is a meshwork of specialized fibroblastic cells called …, and a delicate web of reticular fibers supporting the hematopoyetic cells and macrophage
Stromal cells, also called reticular or adventitial cells
The matrix of bone marrow also contains
Collagen Type I, proteoglycans, fibronectin and laminin the latter glycoprotein interacting with integrins to bind cells to the matrix
The red marrow is also a site where
Older, defective erythrocytes undergo phagocytosis by macrophages which then reprocess hemebound iron for delivery to the differentiating erythrocytes
The major activities that regulates activities and cytokine secretion of many leukocytes and other cells and important source is in macrophages and T helper cells
Interleukin 1 IL 1
The major activities is in mitogen for activated T and B cells, promotes differentiation of NK cells
Inteleukin 2
Mitogen for all granulocytes and Megakaryocytes progenitor cells
Interleukin 3
Promotes development of Basophils and mast cells and B lymphocytes activation
Interleukin 4
Promotes development and activation of Eosinophils
Interleukin 5 or Eosinophils differentiation factor EDF
Mitogen for many leukocytes , promotes activation of B cells and regulatory T cells
Interleukin 6
Major mitogen for all lymphoid stem cells
Interleukin 7
The hematopoietic niche in marrow includes
Stroma
Osteoblast
Megakaryocytes
Secret various CSF
Stromal cells and bone cells
Stromal cells produce
ECM
Between the hematopoietic cord run….. Which have discontinuous endothelium, through which newly differentiated blood cells and platelets enter the circulation
Sinusoids
Erythropoiesis Consist in
Cell and nuclear volume decrease Chromatin density increases Gradual decrease in the number of polyribosomes Increase in the amount of hemoglobin Organelles disappear
The development of An erythrocytes from its first recognizable progenitor cell to the release of reticulocytes into the blood takes approximately
1 week
A growth factor produced by cells in the kidney stimulates the production of mRNA for globins,
Erythropoietin
The protein components of hemoglobin and is essential for the production of erythrocytes
Globins
A large cell with loose, lacy chromatin, nucleoli, and Basophilic cytoplam, the distinct progenitor cell of the erythroid series is the
Proerythroblast
More strongly Basophilic Cytoplasm and a condensed nucleus with no visible nucleolus. The basophilia is caused by the large number of polysomes synthesizing hemoglobin
Basophilic erythroblast
Producing regions of both basophilia and acidophilia in the cell now called
Polychromatophilic erythroblast
The cell and nuclear volumes continue to condense and no basophilia is evident resulting una uniformly Acidophilic Cytoplasm
Orthochromatophilic erythroblast also called normoblast
The cells ejects its nucleus which is then phagocytosed by macrophage , the cells till has a small number of polyribosomes is called
Reticulocytes
Reticulocytes constituted ..% of the red blood cells circulating
1%
Involves cytoplasmatic changes dominated by synthesis of proteins for the azurophilic granules and specific granules
Granulopoiesis
Contains lysosomal hydrolases stain with basic dyes and are basically similar in the three types of granulocytes
Azurophilic granules
Is the most immature recognizable cell in the myeloid series, disperse chromatin and faint nucleoli
Myeloblast
Basophilic Cytoplasm and azurophilic granules containing lysosomal enzymes and myeloperoxidase, actívate different set of genes resulting in lineage of the three types of granulocytes
Promyelocytes
The first visible sign of this differentiation appears in the
Myelocytes
Stage in which specific granules gradually increase the number and eventually occupy most of the cytoplasm
Metamyelocyte
Before its complete maturation the neutrophilic granulocytes passes through an intermediate stage, in which the nucleus is elongated but not yet polymorphic.
Band cell or stab cell
The appearance of large Numbers of immature neutrophils (band cells) in the blood, sometimes called a “shift to the left” is clinically significant usually indicating a
Bacterial infection
The total time required for a myeloblast to produce mature, circulating neutrophils ranges from
10 to 14 days
Four functionally and anatomically defined compartments
The granulopoietic compartment in active marrow
Storage as mature cells in marrow until release
The circulating population
A population undergoing margination
Inflamed connective tissues thus form a fifth terminal compartment for neutrophils where
The cells reside for a few days and then die by apoptosis
No cytoplasmic granules
Myeloblast
Azurophilic granules being secreted in golgi apparatus in granulopoiesis
Promyelocyte
Moderate number of azurophilic granules and initial production of specific granules in golgi zone
Myelocytes
Abundant specific granules and dispersed azurophilic granules and golgi apparatus reduced
Metamyelocyte
An increase in the number of circulating neutrophils can be…, can cause neutrophils in the marginating compartment to move to the circulating compartment
Intense muscular activity
Administration of epinephrine
A large cell with Basophilic cytoplasm and a large, slightly indented nucleus, nucleoli are evident
Promonocyte
Promonocyte divide twice as they develop into
Monocytes
Monocytes circulate in blood for several hours and enter tissues where they mature as
Macrophage and function for up to several months
Circulating lymphocytes originate mainly in
The thymus and the peripheral lymphoid organs
Lymphoid organs
Spleen
Lymph nodes
Tonsil
All lymphocyte progenitor cells originate
In the bone marrow
The first identifiable progenitor of lymphoid cells is the
Lymphoblast
A large cell capable of dividing two or three times to form
Lymphocytes
Compartment in the bone marrow with developing progenitor cells
Granulopoietic
(Reserve) compartment, also in red marrow, acts as a buffer system, capable of releasing large Numbers of mature neutrophils as needed. Trillions of neutrophils typically move from marrow to the bloodstream every day
Storage
Compartment, in which cells temporarily do not circulate but. Rather accumulate temporarily at the surface of the endothelium in venules and small veins with a half life cells in these two compartments less than 10 hours
Marginating
The Granulopoietic and storage compartment together include cells in approximately the first
14 days
Are malignant clones of leukocytes precursor
Leukemias
Are malignant clones of leukocytes precursor in both limphoid tissue
Lymphoblastic Leukemias
Are malignant clones of leukocytes precursor and bone marrow
Myelogenous Leukemias
A needle is introduced through the compact bone,typically at the iliac crest, and a sample of marrow is withdrawn.
Bone marrow aspirations
Megakaryoblasts which differentiate in Megakaryocytes in a Process driven by
Thrombopoietin
The megakaryoblast diameter, with a large ovoid or kidney shaped nucleus
25 to 50 micrometer
Before differentiating these cells undergo endomitosis with repeated round DNA replication not separated by cell division resulting in a nucleus that is highly polyploid
64N
Megakaryocytes are giant cells,up to … In diameter
150 micrometer with a large irregularly lobulated polyploid nuclei
To form platelets, Megakaryocytes extend several long >100 micrometer branching processes called…, celular extensions penetrate the sinusoidal endothelium and are exposed in the circulating blood of the Sinusoids
Proplatelets
Internally Proplatelets have
Framework of actin filaments and loosely bundled, mix polarity microtubules along which membrane vesicles
Mature Megakaryocytes have numerous invaginations of plasma membrane ramifying throughout the cytoplasm called
Demarcation membranes
A reduction in the number of circulating platelets
Thrombocytopenia
Deficiencies of folic acid or vitamin B12
Ineffective megakaryopoiesis
The color of small spots or petechiae in the skin from poorly inhibited bleeding
Thrombocytopenic purpura