Chapter 7 Hematopoiesis

when does hematopoiesis begin in the bone marrow in the fetus?

5th month of development

when does hematopoiesis in the fetal liver start to decline?

6th month of development, retaining minimal activity until 1 to 2 weeks after birth.

Bone forming cells are called

osteoblasts

bone resorbing cells are called

osteoclasts

morphologic features associated with maturation:

overall decrease in cell volume and a decrease in the ratio of nucleus to cytoplasm, loss of nucleoli, condensation of nuclear chromatin, decrease in nucleus diameter

what happens after a splenectomy?

platelet and leukocyte counts increase

culling

process where cells are phagocytized with subsequent degradation of cell organelles

pitting

process where splenic macrophages remove inclusions or damaged surface membranes from circulating RBCs

Hematopoiesis

production of blood cells

Erythropoiesis

production of erythrocytes in the bone marrow

Megakaryopoiesis

production of platelets

Leukopoiesis

production of white blood cells

Common myloid progenitor

proliferate and differentiates into granulocytic, erythrocytic, monocytic, and megakaryocytic lineages

common lymphoid progenitor

proliferates and differentiates into t, b, and natural killer lymphocyte and dendritic lineages

the largest lymphoid organ in the body:

spleen

which organ filters the circulating blood?

spleen

which organ serves as a storage site for platelets?

spleen

secondary lymphoid tissue consists of:

spleen, lymph nodes, mucosa associated lymphoid tissue

which cells play a critical role in the regulation of hematopoietic stem and progenitor cell survival and differentiation

stromal cells

instructive model

The microenvironment in the bone marrow determines whether the HSC will self-renew or differentiate

hematopoietic stem cells produce all lineages of blood cells in sufficient quantities over the lifetime of an individual because they:

How the ability of self-renewable by asymmetric division

primary lymphoid tissue consists of:

The bone marrow and thymus

endothelial cells:

broad flat cells that form a single continuous layer along the inner surface of the arteries, veins, and vascular sinuses.

BFU-E

burst forming unit erythroid, earliest identifiable colony of RBCs. resemble cluster of grapes containing brightly colored hemoglobin

when does the bone marrow become the primary site of hematopoiesis?

by the end of 24 weeks gestation

undifferentiated HSC's

can differentiate into progenitor cells committed to either lymphoid or myeloid lineages

Interleukins are

cytokines

Interleukins have synergistic interactions with other:

cytokines

what does red marrow contain?

developing blood cells and their progenitors

stromal cells in bone marrow

endothelial cells, adipocytes, macrophages and lymphocytes, osteoblasts, osteoclasts and reticular adventitial cells

splenomegaly

enlargement of the spleen

GM-CSF

induces expression of genes that stimulate HSC differentiation to the common myeloid progenitor

adentitis

infection of the lymph node

inner region of lymph nodes:

medulla

Interleukins exhibit:

multiple biologic activities, such as regulation of autoimmune and inflammatory reactions and hematopoiesis

germinal centers

nodes and nodules have sites for rapidly dividing B cells and plasma cells

the nutrient and oxygen requirements of the marrow are supplied by the:

nutrient and periosteal arteries

How does yolksack hematopoiesis differ from fetal and adult hematopoiesis?

occurs intervascularly (within developing blood vessels)

asymmetric division

one daughter cell returns to the stem cell pool and the other daughter cell undergoes differentiation or apoptosis

Paracortex

t cell rich area of the lymph node

which one of the following cells is a product of the CLP?

t lymphocyte

stochastic model

theory that hematopoiesis is a random process whereby the HSC randomly commits to self-renewal or differentiation

where is the site of major t cell production in the fetus?

thymus

red pulp of the spleen contains:

vascular sinuses separated by cords of reticular cell mesh work

when does hepatic phase of hematopoiesis begin?

5 to 7 gestational weeks

adipocytes become more abundant between what ages?

5 to 7 years of age

CD7 is seen on:

T-lymphoid progenitor and natural killer cells

normal mitotic index

1%-2%

EPO serves to:

1. recruit CFU-E from the more primitive BFU-E compartment 2. Prevents apoptosis of erythroid progenitors 3. induces hemoglobin synthesis

HSC's are directed to one of three possible fates:

1. self-renewal 2. differentiation 3. apoptosis

three main functions of the lymph nodes:

1. site of lymphocyte proliferation from the germinal centers 2. involved in the initiation of immune response to foreign antigens 3. filter particulate matter, debris, and bacteria entering the lymph node via the lymph

what is the lifespan of red blood cells?

120 days

when does hematopoiesis begin in embryonic development?

19th day after fertilization

HSC's exist in the marrow in the ratio of:

1:1000 nucleated blood cells

when does hematopoiesis in the fetal liver reach its peak?

3rd month of fetal development

Monophyletic Theory

All blood cells arise from a common stem cell

CD19 is seen on:

B-lymphoid progenitors

Porphyria's:

Disorders associated with heme synthesis

what growth factor is produced in the kidneys and is used to treat anemia associated with kidney disease

EPO

which one of the following cytokines is required very early in the differentiation of a hematopoietic stem cell?

FLT3 ligand

T/F CSF (colony stimulating factor) only stimulates one type of cell lineage

False. CSF may show specificity for one cell lineage, but is capable of influencing other cell lineages as well.

Thymus

Gland in the thoracic cavity above the heart where T lymphocytes mature.

symmetric division

HSC dividing into two identical daughter cells that follow the path of differentiation

These cells are macrophages that remove senescent cells and foreign debris from the blood that circulates through the liver:

Kupffer cells

T/F One HSC is able to reconstitute the entire hematopoietic system of a lethally irridated host

True

T/F yellow marrow is capable of reverting back to active marrow in cases of increased demand on the bone marrow, such as an excessive blood loss or hemolysis.

True

Stem Cell Theory

a series of experiments conducted by Till and McCulloch in 1961

what does yellow marrow contain?

adipocytes, undifferentiated mesenchymal cells, macrophages

Kit Ligand (Stem Cell Factor)

binding of kit ligand to the kit receptor triggers cytoplasmic domain to induce signals sent to the nucleus of the HSC, stimulating the cell to proliferate

marginal zone of the spleen contains:

blood vessels, macrophages, memory B cells, and CD 4 + t cells

where does hematopoiesis take place in adults?

bone marrow

where is hematopoietic tissue located in adults?

bone marrow, lymph nodes, spleen, liver, thymus

red marrow

composed of the hematopoic cells and macrophages arranged in extravascular cords

IL-3

controls production, differentiation, and function of granulocytes and macrophages

outer region of lymph nodes:

cortex

when a patient has severe anemia and the bone marrow is unable to effectively produce red blood cells to meet the increase demand, one of the body's responses is:

extramedullary hematopoiesis in the liver and spleen

is hepatic hematopoeisis intravascular or extravascular?

extravascular

group of glycoproteins that regulate the proliferation, differentiation, and maturation of hematopoietic precursor cells

hematopoetic growth factors

How does hematopoiesis progress in fetal development?

hematopoiesis starts in the yolk sac, progresses to the AGM region, then to the fetal liver and finally resides in the bone marrow.

what plays an important role in nurturing and protecting HSCs

hematopoietic inductive microenvironment

what cells are arranged in radiating plates emanating from a central vein?

hepatocytes

thymus medulla

holding zone for mature T cells

the best source of active bone marrow for me 20-year-old would be:

iliac crest

where is the site of B cell production in the fetus?

kidney and spleen

non-development of the thymus during gestation results in:

lack of formation of t lymphocytes

medullary cords

lie interior of the lymph node and consist primarily of plasma cells and B cells

A small amount of EPO is produced by the:

liver

where is the major site of hematopoiesis during the second trimester of fetal life?

liver

Interleukins (cytokines) are effective at ____ concentrations

low

Lymph fluid is characterized by:

low protein concentration and the absence of RBCs

white pulp of the spleen contains:

lymphocytes, macrophages, and dendritic cells

EPO is a lineage-specific glycoprotein produced in the:

renal peritubular interstitial cells