- Granulocytes: Neutrophils, Eosinophils, Basophils - Lymphocytes: T cells, B cells, Natural Killer cells - Monocytes (and macrophages)

1) Hematopoiesis Flashcards by Samantha Boyer

hematopoiesis

process of blood cell production and development

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categories of wbcs

Granulocytes: Neutrophils, Eosinophils, Basophils
Lymphocytes: T cells, B cells, Natural Killer cells
Monocytes (and macrophages)

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organs of the hematopoietic system

bone marrow
liver
spleen
thymus
lymph nodes
RES (MPS)

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The hematopoietic system is able to respond to …. by increasing production of the cell type needed.

infection, bleeding or hypoxia

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hematopoiesis does not occur in the…

RES (MPS)
lymph nodes

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————– in which the development of the hematopoietic cells takes place lie just outside the marrow sinuses.

Hematopoietic cords

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structure of marrow:

Several sinuses combine in a ————-, forming a —————- that enters the systemic circulation.

collecting sinus
central vein

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function of thymus

serves as a compartment for maturation of T lymphocytes

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The liver is not as effective as the spleen in…

filtering abnormal erythrocytes

because of rapid flow of blood past hepatic macrophages

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cleans most of the particulate matter from the blood

liver

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discriminating blood filter

spleen

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spleen receives —% of cardiac output

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2 spleen pathways

closed path (rapid)
open path (slow)

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How does the open path in the spleen elimintate weak RBCs?

the hypoxic, acidic and hypoglycemic environment allows only the strongest cells to survive

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5 functions of spleen

culling
pitting
immune defense
platelet storage
extramedullary hematopoiesis

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culling

removing old/damaged RBCs

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pitting

plucking out inclusions from RBCs

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pitting results in…

spherocytes

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spleen’s immune function most important in…

young children developing immunity

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—- of platelets are stored in spleen
damage causes…
splenomegaly causes…

1/3
increased PLT ct
decreased PLT ct

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MPS

mononuclear phagocyte system (RES)

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fixed macrophages are found in…

marrow
liver
spleen
lymph nodes
lungs

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functions of monos/macros

phagocytosis
presentation to T-cells
secretion of growth factors

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Embryonic blood cells, excluding lymphocytes, originate from the…

mesenchymal tissue that arises from the embryonic germ layer, the mesoderm

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sites of blood cell development in fetus

1. Mesoblastic (mesoderm of yolk sac) 2. Hepatic—starting at 2 months gestation 3. Medullary—starting at 7 months gestation 4. Extramedullary—if need for cells is great

primitive erythropoiesis

production of large erythroid cells in mesoderm of yolk sac

Platelets appear at --- months gestation, and granulocytes at --- months

3 5

As the child grows, long bone marrow is replaced with...

yellow marrow (fat cells)

By age 18-20, hematopoiesis occurs in the...

axial skeleton (skull, vertebrae, ribs, sternum, pelvis)

precursor cells are directed by ----------

cytokines

proliferation

rapid cell reproduction

differentiation

appearance of different capabilities in cells that were originally the same

commitment

the instance when a cell takes on a specific route of development

maturation

development of a cell from the “committed” stage to the fully mature stage at which the cell has all of its characteristics

3 compartments of hematopoietic cells

1. Hematopoietic Stem Cells (HSC) 2. Progenitor Cells 3. Maturing Cells

0.5% of total immature hematopoietic cells

HSC | 20,000 total

pluripotential cells capable of giving rise to all lineages of hematopoietic cells

HSC

HSC marker

CD34

3 fates of HSC

1. self-renewal (make exact replica of itself) 2. differentiation (develop into cell with different capabilities) 3. apoptosis (cell death)

cannot self-renew, but they are capable of differentiation

progenitor cells

3% of the total immature hematopoietic cell population

progenitor cells

3 types of progenitor cells

Multipotential Progenitor Cell (MPP) Common Myeloid Progenitor (CMP) Common Lymphoid Progenitor (CLP)

A cell that is going to differentiate (not self renew), but is not committed to any specific cell line yet.

multipotential progenitor cell (MPP)

The youngest cell that is committed to differentiating into one of the following cell lines: Granulocyte Erythrocyte (RBC) Monocyte Megakaryocyte (platelet)

common myeloid progenitor (CMP)

The youngest cell that is committed to differentiating into a lymphocyte.

common lymphoid progenitor (CLP)

The cells of this group are committed to ONE cell line. They are morphologically identifiable.

maturing cells

95% of the total immature hematopoietic cell pool

maturing cells

-blast

earliest maturing cell

soluble mediators that control hematopoiesis

growth factors (GF) or colony stimulating factors (CSF)

an interleukin number is assigned when...

AA sequence is defined

functions of GFs

- suppress apoptosis - promote proliferation - control and regulate differentiation - enhance functional activity of terminally differentiated progeny of precursor cells

most GFs are produced by...

stromal cells (monocytes, macrophages, activated T lymphocytes, fibroblasts, endothelial cells, osteoblasts, adipocytes)

EPO is induced by...

hypoxia

EPO mainly affects...

CFU-E

most GFs are ----------

glycoproteins

2 ways for GFs to stimulate hematopoiesis

- directly – binds to the target cell’s receptor & induces the response on that cell - indirectly – binds to receptor on accessory cell & induces release of another cytokine that acts directly on the target cell (example: IL-1)

GFs that affect predominantly 1 lineage

lineage-restricted

GFs that influence activity of a wide spectrum of progenitor cells

multilineage

At the ------ stage, the cells develop the Rh antigens and erythropoietin receptors.

CFU-E

GFs that inhibit cellular proliferation

negative regulators

examples of negative regulators

TGF-β (transforming growth factor-β) TNF-α (tumor necrosis factor-α) prostaglandins (E series) SCI (stem cell inhibitor)

Procrit

Synthetic EPO. Stimulation of erythropoiesis in renal disease or after chemotherapy.

Neupogen

Recovery from treatment induced myelosuppression (to accelerate bone marrow recovery after intense chemo or radiation therapy). G-CSF and GM-CSF.

erythropoietic island

central macrophage surrounded by nucleated red blood cells (taking iron)

progeny of CLP

- CFU-B - CFU-TNK - Dendritic cell

progeny of CMP

CFU-GEMM