2. HEMATOPOIESIS PART 1 Flashcards
It is a continuous and regulated process of blood cell production that includes cell renewal, proliferation, differentiation, and maturation.
hematopoiesis
organs involved in hematopoieis
bone marrow, liver, spleen, lymph nodes, thymus
stages of hematopoiesis
mesoblastic, hepatic, myeloid
when does mesoblastic phase begin?
19th day of gestation
what type of hematopoiesis happens in the mesoblastic period?
primitive hematopoiesis
in the mesoblastic stage, cells from the mesoderm migrate in these two locations:
yolk sac, aorta-gonad mesonephros
cells from the mesoderm that migrate to the central cavity of the yolk sac form into?
primitive erythroblasts
cells from the mesoderm that surround the cavity of the yolk sac form into?
angioblasts
angioblasts will eventually form what structures
blood vessels
cells from the mesoderm that migrate to the aorta-gonad mesonephros region will form?
hematopoietic stem cells
what is the purpose of primary erythroblasts?
produce hemoglobin needed for delivery of oxygen to rapidly developing embryonic tissues
embryonic hemoglobins
gower 1, gower 2, portland
yolk sac hematopoiesis is (intra/extravascular)?
intravascular
start of the hepatic stage of hematopoiesis
5th to 7th week of gestation
this marks the definitive stage of hematopoiesis
hepatic stage
the stage of hematopoiesis that is marked by the presence of recognizable developing erythroblasts, granulocytes, monocyte
hepatic phase
first fully developed organ in the hepatic stage; major site of T cell production
thymus
the site of b cell production in the hepatic stage
kidney and spleen
will gradually decrease granulocyte production and starts to mainly focus on lymphopoiesis during the hepatic stage
spleen
the predominant hemoglobin in the hepatic stage
Hb F
hepatic hematopoiesis is (intra/extravascular)?
extravascular
it is when medullary hematopoiesis begins
5th month of gestation
site of myeloid hematopoiesis
bone marrow
in medullary hematopoiesis, these cells begin to migrate into the core of the bone
HSCs, mesenchymal cells
these cells continue to proceed with hematopoiesis as they migrate to the bone marrow
Hematopoietic stem cells
in the myeloid stage of hematopoiesis, these cells differentiate into stromal cells
mesenchymal cells
it is the week where the bone marrow becomes the primary site of hematopoiesis
end of the 24th week gestation
it is the week where the bone marrow becomes the only normal site of blood cell production
3 weeks postpartum onwards
specific medullary hematopoietic sites in children
skull, clavicle, sternum, ribs, vertebrae, pelvis, long bones of arms & legs
specific medullary hematopoietic sites in adults
flat bone only: skull, clavicle, sternum, ribs, vertebrae, pelvis, proximal ends of long bones of arms & legs
percentage of hemoglobin in neonates in myeloid hematopoiesis
Hb F (60-80%)
Hb A (20-40%)
percentage of hemoglobin in adults in myeloid hematopoiesis
Hb A1 (>95%)
Hb A2 (1.5-3%)
Hb F (<1/2%)
the myeloid to erythroid ration in the medullary phase
3:1/4:1
These five are within measurable levels during myeloid phase.
EPO
G-CSF
GM-CSF
Hb F
Hb A
The counterpart of fetal hepatic period in infants is the ________________ in adults
extramedullary hematopoiesis
it is where extramedullary hematopoiesis
liver, spleen
contains developing erythroid, myeloid, megakaryocytic, and lymphoid cells
bone marrow
consists of the bone marrow and thymus and is where T and B lymphocytes are derived
primary lymphoid tissue
where lymphoid cells respond to foreign antigens
secondary lymphoid tissue
secondary lymphoid organs
MALT, lymph nodes, spleen
two major components of the bone marrow
red marrow, yellow marrow
hematopoietically active marrow
red marrow
the red marrow consists of:
developing blood cells and their progenitors
hematopoietically inactive marrow
yellow marrow
the yellow marrow consists of:
adipocytes, undifferentiated mesenchymal cells and macrophage
infant contain ____% marrow
100%
replacement of active marrow by adipocytes; a reversible process
retrogression
ratio of red and yellow marrow in adults
50/50 (flat cells: 10-50% | blood cells: 40-60)
the bone marrow contains:
hematopoietic cells, stromal cells, blood vessels
support blood cells in the bone marrow
stromal cells
(stromal cells) broad, flat cells that form a single continuous layer along the inner surface of the arteries, veins, and vascular sinuses
endothelial cells
(stromal cells) large cells with a single fat vacuole; they play a role in regulating the volume of the marrow, and contain growth factors that positively stimulate HSC numbers and bone homeostasis
adipocytes
(stromal cells) function in phagocytosis, and both macrophages and lymphocytes secrete various cytokines that regulate hematopoiesis
macrophages and lymphocytes
(stromal cells) bone forming and resorption cells
osteoblasts and osteoclasts
(stromal cells) cells form an incomplete layer of cells on the abluminal surface of the vascular sinuses
reticular adventitial cells
are stromal cells in the bone marrow that are involved in cytokine production
reticular adventitial, endothelial, macrophages and lymphocytes
(niches in ev cords) they develop in small clusters, and the more mature forms are located adjacent to the outer surfaces of the vascular sinuses
erythroblasts
(niches in ev cords) are located adjacent to the walls of the vascular sinuses, which facilitates the release of platelets into the lumen of the sinus
megakaryocytes
(niches in ev cords) located deep within the cords. As these maturing granulocytes proceed along their differentiation pathway, they move closer to the vascular sinuses.
metamyelocytic stage of immature myeloid cells
hemapoietic cells are arranged into ______________ in the bone marrow
extravascular cords
are spongy structures within the bone that supports hematopoietic cells in the bone marrow
trabeculae
are the blood vessels that supplies nutrient and oxygen requirements of the marrow
nutrient and periosteal arteries
artery that supplies blood only to the marrow
nutrient artery
artery that provides nutrient for the osseous bone and the marrow
periosteal artery
it is where blood vessels enter and exit the bone marrow
bone foramen
major site of blood cell production during the second trimester of fetal development.
liver
chief functional cells of the liver
hepatocytes
macrophages in the liver that remove senescent cells and foreign debris from the blood that circulates through the liver
kupffer cells
where kupffer cells are located
lumen of vascular sinusoids
Largest lymphoid organ in the body; serves as indiscriminate filter of blood
spleen
the spleen contains how many mL of blood
350 mL
three types of splenic tissue
white pulp, red pulp, marginal zone
consists of follicles with germinal centers (lymphocytes, macrophages, & dendritic cells)
white pulp
region where arteries (passing thru germinal centers) are surrounded by aggregates of T lymphocytes
PALS (periarteriolar lymphatic sheath)
interspersed along the periphery of the PALS
Lymphoid nodules
lymphoid nodules contain primarily of?
B lymphocytes
composed primarily of vascular tissues separated by cords of Billroth containing macrophages
red pulp
surrounds the white pulp; forms a reticular meshwork containing blood vessels, macrophages, memory B cells and CD4+ T cells
marginal zone
Two methods of senescent or abnormal RBC removal from circulation
culling, pitting
cells are phagocytized with subsequent degradation of cell organelles
culling
splenic macrophages remove inclusions or damaged surface membrane from the circulating RBC
pitting
approximately how many platelets are sequestered in the spleen
30%
Enlarged, palpable spleen that occurs due to chronic leukemias, inherited membrane or enzyme defects in RBCs, hemoglobinopathies, Hodgkin disease, thalassemia, malaria, and the myeloproliferative disorders.
splenomegaly
in splenomegaly, circulating platelets (increase/decrease)?
decreased
in sickle cell anemia, repeated splenic infarcts caused by sickled RBCs trapped in the small-vessel circulation of the spleen cause tissue damage and necrosis, which often results in:
autosplenectomy
Enlargement of the spleen resulting in some degree of pancytopenia despite the presence of a hyperactive bone marrow
hypersplenism
May be beneficial in cases of excessive destruction of RBCs, such as autoimmune hemolytic anemia when treatment with corticosteroids does not effectively suppress hemolysis or in severe hereditary spherocytosis
splenectomy
in asplenic conditions, circulating platelets (increase/decrease)?
increased (thrombocytosis)
Organs of the lymphatic system located along the lymphatic capillaries; Bean-shaped structure
Lymph nodes
fluid portion of the blood that escapes into the connective tissue; Low protein concentration and no RBCs
Lymph
lymph enters the lymph nodes in the:
afferent lymphatic vessels
lymph exits the lymph nodes in the:
efferent lymphatic vessels
region of the spleen
cortex, medulla
the outer capsule of the lymph nodes forms trabeculae and divides it into:
follicles
foci of activated B cell proliferation developed by some follicles after antigenic stimulation
germinal centers
follicles with no germinal centers
primary follicles
follicles with germinal centers
secondary follicles
region of the spleen that consist primarily of plasma cells and B cells
medullary cords
region in the lymph nodes between cortex and medulla that contains predominantly T cells and macrophages
paracortex
functions of the lymph node
- Site of lymphocyte proliferation
- Initiation of the specific immune response to foreign antigens
- Filter particulate matter, debris, and bacteria entering the lymph node
infection of the lymph node
adenitis
well-developed organ at birth
thymus
the thymus is populated with:
primitive lymphoid cells from yolk sac & liver
the waiting zone that is densely populated with progenitor T cells
cortex
contains 15% mature T cells and is the holding zone for mature T cells
medulla
