Hematopoiesis Flashcards
____ is the controlled, continuous, regulated process of blood cell production.
Hematopoiesis
Hematopoiesis deals with the following: ____.
- Cell renewal
- Proliferation
- Differentiation
- Maturation
____ result in the formation, development, and specialization of all functional blood cells.
Hematopoiesis
Blood cells produced through Hematopoiesis are released from the ____.
bone marrow
A ____ is capable of self-renewal and directed differentiation into all required cell lineages.
Hematopoietic Stem Cell (HSC)
Hematopoiesis in the developing human can be characterized as a ____ in specific sites that rapidly changes during development.
select distribution of embryonic cells
Hematopoiesis in healthy adults is restricted primarily to the ____.
bone marrow
During fetal development, the restricted, sequential distribution of cells is initiated in the ____ and then progresses in the ____, then to the ____, and finally resides in the ____.
- Yolk sac
- Aorta Gonad Mesonephros (AGM) region (mesoblastic phase)
- Liver (hepatic phase)
- Bone marrow (medullary phase)
Stages of Hematopoiesis
- Mesoblastic Phase
- Hepatic Phase
- Medullary Phase
Mesoblastic Phase
Hematopoiesis is considered to begin around ____.
19th day of gestation
Mesoblastic Phase
Chief site
Yolk sac
Mesoblastic Phase
Cells from the mesoderm migrate to the ___.
Yolk sac
Mesoblastic Phase
Cells from the ____ migrate to the yolk sac.
mesoderm
Mesoblastic Phase
Some of the cells form ____ in the central cavity of the yolk sac.
primitive erythroblasts
Mesoblastic Phase
Type of cell produced
Erythroblast
immature or primitive RBC
Mesoblastic Phase
____ surround the cavity of the yolk sac and eventually form blood vessels.
Angioblasts
Mesoblastic Phase
The transient yolk sac erythroblasts are important in early embryogenesis to produce ____.
Hemoglobin
Mesoblastic Phase
____ is needed for the delivery of oxygen to rapidly developing embryonic tissues.
Hemoglobin
____ is a protein made up of 4 units of heme that is paired with a globin.
Hemoglobin
Hemoglobin is made up of ____ units of heme and globin.
4
What differentiates the mesoblastic phase from all the different phases of hematopoiesis?
It occurs intravascularly (within the developing blood cells)
Mesoblastic Phase
The yolk sac can remain active up to ____ of gestation.
8 to 12 weeks
____ are only present during the mesoblastic stage or embryonic life.
Embryonic hemoglobins
Embryonic hemoglobins
- Gower I
- Gower II
- Portland
Which Embryonic Hemoglobin?
2 epsilon + 2 zeta globin chains
Gower I
Gower I globin contents
- 2 Epsilon globin chains
- 2 Zeta globin chains
Which Embryonic Hemoglobin?
2 alpha + 2 epsilon globin chains
Gower II
Gower II globin contents
- 2 Alpha globin chains
- 2 Epsilon globin chains
Which Embryonic Hemoglobin?
2 zeta + 2 gamma globin chains
Portland
Portland globin contents
- 2 Zeta globin chains
- 2 Gamma globin chains
Cells of mesodermal origin migrate to the ____ and give rise to HSCs for definitive or permanent adult hematopoiesis during embryonic development.
Aorta-Gonad-Mesonephros (AGM) Region
The ____ was previously considered to be the only site of definitive hematopoiesis during embryonic development.
Aorta-Gonad-Mesonephros (AGM) Region
Hepatic Phase
The hepatic phase of hematopoiesis beings at ____.
5 to 7 weeks of gestation
Hepatic Phase
Types of cell produced
- Erythroblasts
- Granulocytes
- Monocytes
- Lymphoid cells
- Megakaryocytes
The ____ phase is characterized by recognizable clusters of developing erythroblasts, granulocytes, and monocytes.
Hepatic
Hepatic Phase
Chief site
Liver
Hepatic Phase
The peak production of cells occur at the ____.
3rd month of pregnancy
Hepatic Phase
The decline phase occurs ____.
After the 6th month
Hepatic Phase
Other active sites
Spleen, kidneys, thymus, and lymph nodes
Hepatic Phase
The ____ is the predominant hemoglobin.
Hemoglobin F or Fetal Hemoglobin (HbF)
HbF globin content
- 2 Alpha globin chains
- 2 Gamma globin chains
Hepatic Phase
Hemoglobins present
- Hemoglobin F or Fetal Hemoglobin (HbF)
- Hemoglobin A or Adult Hemoglobin (HbA)
2 Types of Hemoglobin A
- HbA1
- HbA2
Which type of HbA?
95%
HbA1
Which type of HbA?
2 alpha + 2 beta globin chains
HbA1
Which type of HbA?
2-3%
HbA2
Which type of HbA?
2 alpha + 2 delta globin chains
HbA2
% content of HbF in adults
1-2%
Medullary phase is also known as the ____.
Myeloid phase
Medullary (Myeloid) Phase
Time
5 to 6 month of gestation
Rodak’s: Between fourth and fifth month
Medullary (Myeloid) Phase
Chief site
Bone marrow
Why is hematopoiesis in the bone marrow termed as medullary hematopoiesis?
Because it occurs in the inner part of the bone cavity, which is the medulla.
Medullary (Myeloid) Phase
Types of cell produced
- Hematopoietic stem cells
- Mesenchymal cells
During the myeloid phase, HSCs and mesenchymal cells migrate to the ____.
core of the bone
____, a type of embryonic tissue, differentiate into structural elements that support developing hematopoietic elements.
Mesenchymal cells
Measurable levels of growth factors are evident in ____ phase.
medullary
Medullary (Myeloid Phase)
The principal source of production are the ____.
Flat bones (e.g. sternum)
At the end of the 24th week of gestation, the ____ will be the main site of hematopoiesis.
Bone marrow
When will the bone marrow be the main site of hematopoiesis?
At the end of 24th week of gestation
The ____ is responsible for the synthesis or production of cells.
Adult Hematopoietic Tissue
____ is where Lymphoid Development occurs.
Adult Hematopoietic Tissue
Primary and Secondary Lymphoid Tissue
Primary Lymphoid Tissues
- Bone marrow
- Thymus
Secondary Lymphoid Tissues
- Lymph nodes
- Spleen
- Liver
- MALT
____ is where B cells and T cells are derived.
Primary Lymphoid Tissue
____ is where lymphoid cells respond to foreign substances.
Secondary Lymphoid Tissue
The ____ develops in the embryo by the hollowing out of the skeletal bone forming a central cavity.
bone marrow
The soft tissue inside the central cavity is called ____.
bone marrow
The bone marrow contains ____.
- Hematopoietic cells
- Stromal cells
- Blood vessels
Main function of bone marrow
Production and proliferation of blood cells
All blood formed elements ultimately develop from the undifferentiated and primitive precursor called ____.
Hematopoietic Stem Cell (HSC)
Hematopoietic stem cell developed from ____.
Hematopoietic cell
The bone marrow is ____ at birth.
red
In young adults, the marrow is about ____ active.
60-70%
The cell production usually happens in the ____.
flat bones
____ is the replacement from red to yellow bone marrow.
Retrogression
____ regulate the microenvironment of hematopoietic tissue so that we can produce cells.
Stromal cells
Kinds of Bone Marrow
- Red
- Yellow
Which Kind of Bone Marrow?
Active
Red
Which Kind of Bone Marrow?
Composed of hematopoietic cells, and macrophages
Red
The red marrow is composed of ____.
- Hematopoietic cells (developing blood cells and their progenitors)
- Macrophages
Which Kind of Bone Marrow?
Components are arranged in extravascular cords
Red
The components of red bone marrow is arranged in ____.
extravascular cords
Hematopoietic cells will later on develop and mature in ____ within the cords.
niches
Usually at birth, the bone marrow is 100% ____.
red
Main functions of Red Bone Marrow
- Production of blood cells
- Iron storage
- B-cell development
Which Kind of Bone Marrow?
Inactive (not capable of producing cells)
Yellow
Which Kind of Bone Marrow?
Composed of adipocytes and undifferentiated mesenchymal cells
Yellow