Hema week 1 Flashcards
What determines the type of hemoglobin?
Globin chains
Globin chains of gower 1 (EZ)
2 Zeta 2 Epsilon
Globin chains of portland hemoglobin (GratZ)
2 Zeta 2 Gamma
Globin chain of gower 2 hemoglobin (AE)
2 Alpha 2 Epsilon
As early as the 19th day of gestation in the blood islands of the yolk sac of the human embryo
Blood islands remain active for 8 to 12 weeks
Mesoblastic
3rd month, yolk sac discontinues its role, fetal liver becomes active
Spleen, thymus, and lymph nodes are active
Primitive cells disappears by the end of the 4th month, with an increase in the definitive erythroblast, granulocytes, and megakaryocytes
Hemoglobin production: Hb F, Hb A1 and Hb A2
Hepatic
Globin chain composition of Hb F (F AG)
2 alpha 2 gamma
Globin chain composition of Hb A1 (ewan BA)
2 alpha 2 beta
Globin chain composition of Hb A2 (eto DA)
2 alpha 2 Delta
Primary adult hemoglobin
Hemoglobin A1
Primary site of hematopoiesis in adult
Sternum
Safest, most accessible site for bone marrow aspiration and biopsy
Iliac crest
A continuous regulated process of blood cell production that includes cell renewal, proliferation, differentiation, and maturation of the cell
Hematopoietic
Haematopoietically active marrow consisting of the developing blood cells and their progenitors
Red marrow
Haematopoietically inactive marrow composed primarily of ADIPOCYTES and fat cells with undifferentiated MESENCHYMAL CELLS AND MACRHOPHAGES
Yellow marrow
Composition of stroma
Endothelial cells, Adipocytes, Osteoblasts, Osteoclasts, Reticular cells (Fibroblasts), and Macrophages
Regulates the flow of particles entering and leaving hematopoietic spaces
Endothelial cells
Secrete various steroids that influence erythropoiesis and maintain bone integrity and regulates the volume of marrow
Adipocytes
Function in phagocytosis and secretion of various cytokines that regulate hematopoiesis
Macrophages
Bone forming cells-water bug or comet appearance
Osteoblasts
Bone resorbing cells or destroying cells
Osteoclasts
Supports the vascular sinuses and developing hematopoietic cells
Reticular cells (Fibroblasts)
Composition of Extracellular matrix of bone marrow
For regulation of the hematopoietic stem cells and progenitors
For survival and differentiation of cells
For adhesions
- Proteoglycans/Glycosaminoglycans
- Fibronectin
- Collagen
- Laminin
- Hemonectin
- Thrombospondin
Major site of blood cell production during the second trimester of fetal development (Hepatic phase)
Capable of extra medullary hematopoiesis
Functions:
Protein synthesis and degradation, coagulation factor synthesis (except F IV), carbohydrate and lipid metabolism
Drug and toxin clearance
Iron recycling and storage
Hemoglobin degradation
Liver
Largest lymphoid organ in the body
Located directly beneath the diaphragm behind the fundus of the stomach in the upper left quadrant of the abdoment
Vital but not essential for life
Function:
Indiscriminate filter of the circulating blood
Storage for platelets
30% spleen 70% Circulation
Spleen
Disease related to autosplenectomy
Sickle Cell Anemia, Spherocytosis
Regions of spleen
- White pulp - consists of scattered follicles with germinal center containing lymphocytes, macrophages, and dendritic cells
- Red pulp - Composed primarily of vascular sinusoids and sinuses separated
- Marginal zone - Surrounds the white pulp and forms a reticular meshwork containing blood vessels, macrophages, and specialized B cells
Two methods for removing senescent or abnormal RBCs from circulation
Culling and Pitting
Cells are phagocytized with subsequent degradation of cell organelles
Culling
Splenic macrophages remove inclusions or damaged surface membrane from the circulating RBCs
Pitting
Bean-shaped structures (1-5mm)
Functions:
Plays a role in the formation of new lymphocytes from germinal centers
Involved in the processing of specific immunoglobulin
Involved in the filtration of particulate matter, debris, and bacteria entering the lymph node via the lymph
Lymph nodes
Region of lymph nodes
Cortex, Paracortex, and Medulla
Outer region of lymph node
Contains follicles of B cells
Proliferation termed germinal centers
Cortex
Inner region
Consists primarily of T lymphocytes and plasma cells
Medulla
Region between cortex and medulla
Contains predominantly T cells and numerous macrophages
Paracortex
Originates from endodermal and mesenchymal tissues
Populated initially by lymphocytes from the yolk sac and the liver
An efficient, well-developed organ at birth that consists of two lobules each measure 0.5 to 2cm in diameter
Organ responsible in the conditioning of T lymphoctes
Thymus
Cells that have extensive proliferative capacity
- ability to give rise to new stem cell
- Ability to differentiate into any blood cell lines
Hematopoietic stem cells are Bone marrow cells that are capable of producing all types of blood cells
They differentiate into one or another type of committed stem cells( Progenitor cells)
Stem cells
Stimulates proliferation, growth, and differentiation of erythroid precursors and may have minor effects on megakaryocytes
Target cells are pronormoblast and CFU-Erythroid cells
Source: KIDNEY
Erythropoietin (EPO)
The entry of mature blood cells into the intravascular space relies upon:
- Multiplication of developing cells
- Gradual maturation
- Orderly release of cell from bone marrow
3 Possible activities of hematopoietic stem cells
- Self- renewal
- Differentiation
- Apoptosis
Normal blood cells maturation
- Cytoplasmic changes
- Nuclear changes
- Reduction in cell size
Abnormal cell maturation
Characterized by persistent cytoplasmic basophilia and late hemoglobinization
Inclusion bodies may be found
Cells are present in the first few hours after an ovum is fertilized
Most versatile type of stem cell, can develop into any human cell type, including development from embryo into fetus
Totipotential stem cells
Cells are present several days after fertilization
Can develop into any cell type except into a fetus
Pluripotential stem cells
Derived from pluripotent stem cells
Found in adults but are limited to specific types of cells to form tissues
Multipotential stem cells
Size: Large cell with high Nucleus:Cytoplasm ratio
Cytoplasm: Very dark blue (Increase in RNA) and small in amount in comparison to the size of nucleus. No granular is present
Nucleus: Large in size as compared to the size of cytoplasm. Chromatic which is reddish purple and indicated predominance of DNA
Blast
Present only in the bone marrow
Nucleus Cytoplasm ratio - 8:1
Contains one or two nucleoli
Cytoplasm is dark blue because of the concentration of ribosomes
Cellular activity: Accumulates the components necessary for hemoglobin production
Enzymes and proteins necessary for iron uptake and protoporphyrin synthesis are produced
Globin production begins
Stage last more than 24 hours
Mitosis is present = 2 prorubricyte
Pronormoblast/Rubriblast
Nucleus: Chromatin begins to condense
N:C ratio decrease to about 6:1
Chromatin stains deep purple red
Nucleoli may be present early in the stage but disappear later
Mitosis is present = produces 4 rubricyte
Bone marrow is the location
Detectable hemoglobin synthesis occurs. (1st stage of hemoglobin synthesis)
Mistaken as Rubriblast
Prorubricyte / Basophilic normoblast
Differentiation of prorubricyte to rubricyte
- Coarse Chromatin
- Nucleoli are absent. (Present in the early stage but disappear later)
Nucleus: Chromatin pattern varies during this stage of development, showing some openness early in the stage but becoming condense
The condensation of chromatin reduces the diameter of the nucleus considerably so the
N:C ratio decreases from 4:1 to about 1:1 by the end of the stage
NO nucleoli are present
Mitosis is present = 2 metarubricyte
LAST STAGE OF MITOSIS
First stage in which cytoplasm is turning pink
because
Hemoglobin synthesis increases, and the accumulation begins to be visible in the color of the cytoplasm
Last approximately 30 hours
Confused with lymphocyte
Polychromatic normoblast/ Rubricyte
Rubricyte and Lymphocyte differentiation
Lymphocyte - Crushed velvet nucleus
Cytoplasm - Sky blue
Rubricyte -
Nucleus - Checkerboard
Cytoplasm - Muddy/Gray
Nucleus: Completely condensed
N:C ratio is low or approximately 1:2
Cytoplasm: Increase in the salmon-pink color of the cytoplasm reflects the nearly complete hemoglobin production
Division: Not capable of division due to the condensation of the chromatin
Location: Present only in the bone marrow in healthy states
Orthochromic normoblast / Metarubricyte
No nucleus but has mitochondria and ribosomes
Last stage to synthesize hemoglobin
Last stage in bone marrow before release to the blood
Location: Polychromatic erythrocyte resides in the bone marrow for 1 day or longer and then moves into the peripheral blood for about 1 day before reaching maturity
0.5% - 1.5% in adult
2% - 6% in newborn
Indicators of bone marrow functions
Also known as polychromatophilic erythrocytes
Diffusely basophilic erythrocytes
Polychromatophilic macrocytes
Reticulocytes
No nucleus is present
Cytoplasm: Biconcave disc measure 7 to 8 mm in diameter with a thickness of about 1.5 to 2.5 mm
On a stained blood film it appears as a salmon pink-staining cell with a central pale are.
The central pallor is about one third the diameter of the cell
Division: No division (Stops at rubricyte)
Remains active in the circulation for 120 days
Aging leads to their removal at the spleen and by the spleen
Delivers oxygen to tissues, releases it, and returns to the lungs to be reoxygenated
Erythrocytes
- important in terminal erythroid differentiation in terms of
- cell division,
- & cell motility
Actin - Contraction and relaxation of membrane or RBC
Tubulin and actin in reticulocytes membrane
Main function of RBC membrane
Facilitates Iron transport
Maintains the membrane integrity
Maintains the membrane deformability
Constantly changes as it moves through the circulation
Soft and pliable
Biconcave shape (Maximum Surface area)
Consists of a membrane skeleton protein lattice and lipid bilayer
More than 50 transmembrane proteins have been identified and more than half carries blood group antigens
Mature Red Blood cell membrane
Rbc membrane composed of three comoponents
40% Lipids mostly phospholipids, cholesterol
8% carbohydrate linked to lipid or protein
52% glycoproteins
Structure of RBC membrane
Membrane lipids
Outer layer:
Phosphatidyl choline
Sphingomyelin
Inner layer:
Phosphatidyl ethanolamine
Phosphatidyl serine
Structure of RBC membrane
Membrane proteins
Integral protein:
Band 3 (Anion exchanger protein)
Glycophorin
Aquaphorin
Peripheral protein:
Spectrin
Actin
Protein 4.1
Pallidin (Band 4.2)
Ankyrin
Adducin
Tropomycin
Tropomodulin
Peripheral protein is responsible for
Cell shape and structural deformability
Band 3 protein is responsible for
Prevention of Surface Area loss
Binding site of enzyme and cytoplasmic membrane
Anion transport - Exchanges bicarbonate for chloride
Linkage of lipid bilayer to underlying membrane skeleton
- Interaction w/ ankyrin and protein 4.2, secondarily through binding to protein 4.1
Vertical interaction
Stabilizes the lipid bilayer membrane
Horizontal interaction
Support the structural integrity of RBC
Glycophorin
Imparts a negative charge to the cell
Glycophorin A carries MN, Gerbich blood group antigen
Glycophorin C, Glycophorin A important for P. Falciparum invasion and development in RBC
Aquaporin 1
Selective pores for water transport
Allows RBC to remain in osmotic equilibrium with ECF
Red cell membrane skeleton
Hexagonal lattice with 6 spectrin molecules
Each linked to multiple spectrin tetramers
Composed of spectrin, actin, 4.1
Ankyrin links the lipid bilayer to membrane via interaction with band 3
Spectrin is responsible for
Flexible, rod-like molecule
Biconcave shape for red blood cell
Important factor in RBC integrity (Binds to other peripheral proteins e.g actin, ankyrin, adducin) then forms a skeletal network of microfilaments
Two sub-units (Alpha and Beta)
Beta spectrin:
Attachment for ankyrin near C terminus (which binds cytoplasmic tail of band 3) thus attachment of skeleton to lipid bilayer
At N terminus:
Attachment for 4.1 protein (associated with glycophorin C) - second anchor point with lipid membrane
Binding sites for actin filaments and protein 4.1 - forming a junctional complex
Skeletal Network of microfilaments
Strengthen the membrane
Controls the biconcave shape
Controls the deformability of the cell
Provide stability of the RBC
Most abundant peripheral protein
Spectrin
Actin and its function
Contraction and retraction of membrane
Short, uniform filaments
Length modulated by tropomyosin/Tropomodulin
Approximately 6 spectrin ends interface with one actin filament stabilized by protein 4.1
Skeletal RBC protein
Regulates actin proliferation
Tropomyosin
Controls the actin filaments (paghaba)
Tropomodulin
Stabilizes actin-spectrin interaction
Protein 4.1