Hematopoiesis & Erythropoiesis Flashcards
blood volume in females
4-5L
blood volume in males
5-6L
blood pH
7.35-7.45
Blood composition (55%)
Plasma/Serum (fluid)
Water, proteins, other solutes
Blood composition (45%)
Formed elements (cells)
RBCs, WBCs, Platelets
Blood Specific Gravity
1.049-1.065
Centrifuge Blood Sample (Top, middle, bottom)
Top layer - Plasma/Serum
Middle - “Buffy Coat” - WBCs + platelets
Bottom Layer - RBCs
Hematocrit
% of packed red cells
Anticoagulant used
Plasma
Clotting factors present
Example of clotting factor
Fibrinogen
No anticoagulant used
Serum
Some clotting factors consumed
Gold/Red Top in a blood separation sample
No anticoagulant
Green/Purple/Blue - Blood Separation
Anticoagulant present
Blood Collection - Capillary
Adult - fingerstick
Baby - Heel stick
Blood Collection - Venipuncture
Median Cubital
Median Cephalic
Blood Collection - Arterial
Radial Artery
Brachial Artery
Femoral Artery
WBC Count (Conventional Units)
4.8-10.8 x 10^3/ microL
RBC Count - Male
4.7-6.1 x 10^6 / microL
RBC Count - Female
4.2-5.4 x 10^6 / microL
Hematocrit (HTC) Male
42-52%
Hematocrit (HTC) - Female
37-47%
Major Blood Functions
Transport oxygen to cells
Transport CO2 and wastes away
Provides defense
Regulates body pH, body temperature, fluid balance
Major blood functions are required to maintain
Homeostasis
Homeostasis
maintaining a constant environment or equilibrium
Hematopoiesis
Formation of blood cells
Hematopoiesis Characteristics
Takes place in hematopoietic tissue
Maintains a cell population of erythrocytes, leukocytes, platelets.
Responsible for the maturation and division of hematopoietic stem cells
Platelets
G
Erythrocytes
A
Neutrophils
I,E,C
Eosinophil
D
Basophil
J
Lymphocytes
B,H
Monocytes
F
Platelets (Thrombocyte)
Size?
Nucleus?
Average Life Span?
Function?
Size: 1-4 micro m
Cytoplasmic fragment, no nucleus
Average lifespan: 10 days
Function: homeostasis
Platelets Homeostasis
Process in which blood clots and bleeding is arrested
Neutrophil Function
Inflammation & Phagocytosis
1st line of defense against infections
Most abundant
Platelets (Thrombocyte)
Neutrophils
Neutrophil Nucleus
2-5 lobes connected by a thin filament
Segmentation allows passing through openings between lining cells
Neutrophil cytoplasm
light pink with secondary granules (pink/neutral)
Average life span neutrophils
6-10 hrs
Eosinophil
Eosinophil function
defense in parasitic and fungal infections
Eosinophil nucleus
bi-lobed with condensed chromatin
Eosinophil cytoplasm
secondary granules (reddish/orange)
Basophil
Basophil function
mediates allergic reactions
Basophil Nucleus
often obscured by large secondary granules
least abundant WBC in circulation
Basophil cytoplasm
dark secondary granules
- histamine → vasoconstriction
- Heparin → blood thinner
granules are water soluble
What do granules in basophils contain?
Histamine and Heparin (play a role in homeostasis)
histamine
vasoconstriction
heparin
blood thinner (anticoagulant)
Lymphocyte function
immune response and viral infection
lymphocytes
Lymphocyte nucleus
clumped chromatin
lymphocyte cytoplasm
stains blue, periphery more intense
Lymphocyte granules
- usually none
- can have a few (countable) azurophilic granules - reddish pink
Monocyte
Monocyte function
phagocytosis
Monocyte nucleus
- Horseshoe-shaped/lima bean/convoluted
- Lacy, fine chromatin
Shape/outline of monocyte is irregular
Monocyte cytoplasm
- Dull gray-blue
- Cloudy
- Many small, red-purple staining granules
- Vacuoles often present
A - Lymphocyte
B - Monocyte
A - Lymphocyte
B - Monocyte
Surrounding cells Lymph vs. Mono
Lymph - indented by RBCs
Mono - project pseudopods between or compressing nearby RBCs
Mature RBC - Erythrocyte
Major function of mature RBC
Oxygen transport from lungs to tissues
Shape of RBC
6-8 micro m Biconcave Disc (shallow middle)
Allows for max surface area for gaseous exchange
Hemoglobin is 95% dry weight
Mature RBC lifespan
120 day lifespan
Can travel 200-300 miles during this time
Organs within hematopoietic system
Bone Marrow
Liver
Spleen
Lymph Nodes
Thymus
Embryo Developmental Stage
Mesoblastic phase
Fetal Developmental Stage
Hepatic Phase
Birth Developmental Stage
Medullary Phase
Embryo - Mesoblastic phase
- 2 weeks - 2 months gestation
- Yolk sac - mesoderm layer
- Forms primitive erythroid cells
- Hemoglobin formed
- Hgb Gower-1
- Hgb Gower-2
- Hgb Portland
All referred to as embryonic hemoglobin
Fetus - Hepatic Phase
- 2 months - 7 months gestation
- Liver and Spleen
- Additionally forms WBCs and Megakaryocytes (platelets precursor)
- Hgb formed
- Fetal hemoglobin
- Hemoglobin A1 (small amounts)
Birth - Medullary Phase
(bone marrow)
- 7 months - rest of life!
- Bone marrow = intramedullary hematopoiesis
- Red marrow
- Diapedesis
- Hgb formed post birth
- Hemoglobin A1
- Hemoglobin A2 ( small amounts)
Infancy and Early Childhood
Volume of red marrow in infant and adult are approximately equal.
As one is aging, the distal long bones and axial skeleton is expanding
At 4 years, yellow marrow (fat) starts replacing red marrow → limits hemopoietic sites
Adolescence and Adulthood
Only active hemopoietic/red marrow in axial skeleton
- Sternum
- Ribs
- Pelvis
- Vertebrae
- Skull
Other bones contain primarily yellow marrow
At the age of 40+
Only find hematopoietic/red marrow in:
- Sternum
- Ribs
- Pelvis
- Vertebrae
- 50% red, 50% yellow marrow
Preferred bone marrow aspiration sites
Pelvis and Sternum
Last to be replaced by yellow marrow
Monophyletic Blood Cell Development Theory
All blood cells arise from one precursor cell that is multipotential or pluripoential and called stem cells
Considered Proven Theory
Polyphyeltic Blood Cell Developmental Theory
Each blood cell comes from its own seperate precursor
Old Theory - Disproven
Stem cells (Pluripotential vs multipotential)
Pluripotential → can develop into any cell line in the body
Multipotential → can develop into any blood cell line in the body
Cell stays in bone marrow until stimulus for development is given
Once stimulation, converts to a progenitor cell → committed to that cell line
Cytokines
Soluble messages to tell early cells to differentiate
Types of cytokines
Interleukins (IL) and Colony Stimulating Factors (CSF)
- Mediate proliferation, differentiation, maturation of hematopoietic progenitor cells
- One CSF or IL may affect more than one cell line or multiple stages within a cell line
- May require combination to get needed effect
Thrombopoietin
Stimulates CFU - Meg and causes release of platelets
Erythropoietin
Stimulates CFU-E and regulates erythroid progenitor cells to mature
- Glycoprotein produced by the peritubular interstitial cell in the juxtaglomerular apparatus (kidney tubules). Detects amount of oxygen
Lymphoid stem cell (LSC) can differentiate into
T and B Cells
T cells
- Immune functions of cellular nature
- cytotoxic
- suppressing activities
B cells
Immune Function → Antibody production
- can further develop into plasma cells → secrete antibodies
Myeloid Stem Cell
Develops into CFU-GEMM
CFU-GEMM gives rise to
CFU-GM → CFU G and CFU M
CFU-Eo
CFU-Bas
CFU-Meg
CFU-E/BFU-E
CFU G
Neutrophil
CFU M
Monocyte/Macrophage
CFU-Eo
Eosinophil
CFU-Bas
Basophil / Mast Cell
CFU-Meg
Thrombocytes
BFU-E → CFU-E
Erythrocytes
BFU?
Burst Forming Unit
Normal Myeloid : Erythroid ratio
2:1 - 5:1
- Myeloid → non-erythroid cells originating from myeloid stem cell (mainly granulocytes)
- Erythroid → any erythroid stage
WBCs have a shorter life span than RBCs
Erythrocyte maturation
Erythroid nucleus & contents
- Nucleus → site of DNA/RNA synthesis
- Large → small/pyknotic as it matures
-
Chromatin
- DNA, histones, proteins
- Euchromatin → active/finely dispersed/nucleoli present
- Heterochromatin → inactive/condensed nucleoli absent - more heterochromatin as it matures.
-
Chromatin
Eventually nucleus is extruded
Immature Erythroid Cytoplasm
- Small amount since nucleus is so big. High N:C ratio
- Early stages have many ribosomes (RNA) - Basophilic cytoplasm
- Within cytoplasm
- Golgi zone → light staining near nucleus
- Mitochondria → energy production and hemoglobin formation (Fe into heme ring)
Mature Erythroid
- As hemoglobin is formed, less and less RNA
- Dark blue cytoplasm shifts to pink
- N:C ratio decreases → eventually no nucleus
- No golgi zone
- no mitochondria
Synchronous development
nucleus and cytoplasm mature at same rate
Asynchronous development
Growth/maturation of nucleus and cytoplasm is not at the same rate
- Abnormal development
- Example: Megaloblastic anemia
Megaloblastic anemia
Erythrocyte Maturation - as RBC develops….
- Cell volume decreases
- N:C ratio decreases
- Chromatin condense
- Nucleoli disappears
- RNA in cytoplasm decreases
- Hemoglobin synthesis
- gradually increases until a stopping point
- Hemoglobin synthesis
Erythrocytes capable of mitosis
- Pronormoblast
- Basophilic normoblast
- Polychromatophilic normoblast
Normoblast is also called
Rubriblast
Pronormoblast is also called
Rubriblast
Basophilic Normoblast is also called
Prorubricyte
Polychromatophilic Normoblast is also called
Rubricyte
Orhtochromatic normoblast is also called
Metarubricyte
Polychromatophilic Erythrocyte (Macrocyte) is also called
DIffusely Basophilic Erythrocyte
Erythrocyte is also called
erythrocyte
Pronormoblast/Rubriblast
Size?
Nucleus?
Cytoplasm?
NC ratio?
BM%?
Size → 12-24 microm
nucleus → round, central. 2-3 nucleoli, fine diffuse chromatin (euchromatin)
Cytoplasm → stains deep blue (RNA). Often a visible golgi zone
Pronormoblast/Rubriblast
Pronormoblast/Rubricyte
Pronormoblast/Rubricyte
Pronormoblast/Rubriblast
Basophilic Normoblast/Prorubricyte
Size?
Nucleus?
Cytoplasm?
NC ratio?
BM%?
- size → 12-17 microm
- Nucleus → Round, central, no nucleoli, some chromatin granularity
- Cytoplasm → Slightly less Basophilic “cornflower blue”
- NC ratio → 6:1 - 4:1
- BM% → 1-5%
Basophilic Normoblast/Prorubcricyte
Pronormoblast vs. Basophilic Normoblast
Maturation differences
- Less nucleoli
- Beginning chromatin granularity
- Cytoplasm less basophilic
- golgi zone disappears
- slightly smaller in size with decreasing NC ratio
Pronormoblast
Basophilic normoblast
Polychromatophilic Normoblast / Rubricyte
Size?
Nucleus?
Cytoplasm?
NC?
BM%
Size → 10-15 micro m
Nucleus → round central, or slightly eccentric. Nucleoli - none. Chromatin is moderately compacted condensed “soccer ball”
Cytoplasm → hemoglobin synthesis beginning → stains lavender instead of blue
NC ratio → 4:1 - 2:1
BM → 5-30%
Last stage capable of mitosis in Erythrocytes?
Polychromatic Normoblast / Rubricyte
Gives rise to 2 orthochromatic normoblasts
Polychromatic normoblast / Rubricyte
Basophilic normoblast vs Polychromatophilic Normoblast
Maturation differences
- Nucleus can move off center
- chromatin more mature and begins to become pyknotic
- Cytoplasm shifts from blue to purple (hemoglobin)
- Slight smaller in size and NC ratio
Polychromatophilic Normoblast
Orthochromatic Normoblast / Metarubricyte (aka nBRC)
size?
Cytoplasm?
NC ratio?
BM%
size → 8 -12 micro m
nucleus → Last nucleated stage. Round, central or eccentric. Completely pyknotic dark chromatin. “Most perfect circle”
Cytoplasm → Pink or slightly purple cytoplasm. Hemoglobin increasing main constituent. RNA decreasing
NC Ratio → 1:1 - 1:2
BM% → 5-10% can be found in circulation of newborns in normal conditions
Cannot divide further
Orthochromatic Normoblast
Orthochromatic Normoblast
Orthochromatic normoblast
Polychromatophilic Erythrocyte (Macrocyte) / Diffusely Basophilic Cell
Size?
Nucleus?
Cytoplasm?
Size → 8-10 micro m
Nucleus → NONE
Cytoplasm → blue/gray (due to Polychromatophilia), due to residual RNA. Contains mitochondria, loses organelles within 48 hrs in maturation to mature RBC
Last stage to synthesize hemoglobin
Last stage to synthesize hemoglobin?
Polychromatophilic Erythrocyte
Polychromatophilic Erythrocyte
Polychromatophilic Erythrocyte
Orhochroamtic Normoblast → Polychromatophilic Erythrocyte
Maturation Differences
- Nucleus leaves
- cytoplasm is similar in color - pink/purple
- Cell is similar in size
Wrights stain
Polychromatophilic Erythrocyte
New Methylene Blue (Vital Stain)
Reticulocyte
Erythrocyte
Size?
Nucleus?
Cytoplasm?
Size → 7-8 micro m
Nucleus → none
Cytoplasm → pink with central pallor
Found in peripheral blood
No longer able to synthesize new hemoglobin (no mitochondria present)
Mature Erythrocytes
Polychromatiophilic Erythrocyte → Erythrocyte
Maturation Differences
- Cytoplasm loses purple tinge
- Central pallor develops
- slightly smaller in size
RBC membrane - Permeability
- Selective barrier
- Water and anions (-) → passive diffusion
- Cations (+) and other substances → active transport
- Potassium primarily found inside the RBC (25:1)
- Sodium is primarily found outside the RBC (1:12)
- ATP depletion leads to loss of gradient and cell dehydration
- Crucial in
- Controlling RBC volume
- Preventing Colloid Osmotic Hemolysis
RBC membrane - Composition
- Highly Elastic → capable of membrane extension
- Chemical composition
- 50% proteins
- 40% phospholipids and glycolipids
- 10% cholesterol
Layers of RBC membrane
- Outer Hydrophilic Portion → Contains glycolipid, glycoprotein and protein
- Central Hydrophobic Portion → Contains protein, cholesterol, phospholipids
- Inner Hydrophilic Layer → contains protein
Cholesterol in the membrane
- Equally distributed across the central hydrophobic layer → 25% of RBC membrane lipids
Provides continual exchange with plasma cholesterol → affected by body lipid transport
If abnormal, can affect RBC morphology
Acanthocytes
Choline phospholipids
- Phosphatidyl choline + sphongomyelin
- Located on outer half bilayer → closer to the plasma
Amino Phospholipids
Phosphatidylethanolamine and Phosphatidyl Serine
Almost exclusively on inside layer of bilayer
If outside, can initiate clotting mechanism
Integral Membrane Proteins
Traverse entire membrane from outer surface to the inner cytoplasmic side
Ex: Glycophorin
Glycophorin in membrane
- 20% of total membrane proteins
- composed of 60% carbohydrate
- Contributes most of the membrane sialic acid
- causes RBC to have a negative charge that makes them repel each other in the bloodstream
Peripheral Membrane proteins
Cytoplasmic surface of the membrane
Beneath bilayer and forms cytoskeleton
Ex: Spectrin
RBC Cytoskeleton - Inner Hydrophilic Layer
Provides rigid support and stability to bilayer
Responsible for deformability of membrane
Major component of RBC Cytoskeleton Inner Hydrophilic Layer
Spectrin
Ankyrin
Actin
Adducin
Other cytoskeletal proteins
Most important and abundant peripheral membrane protein
Spectrin
Spectrin - Inner Hydrophilic Layer
25-30% of total membrane protein
Makes up 75% of cytoskeleton
Binds other peripheral proteins to make skeletal network
RBC Deformability
Critical for RBC survival through microvasculature + Oxygen deliver function
Depleted ATP
Spectrin phosphorylation decreases → loss of deformability
Increased calcium accumulation and membrane deposition → increased rigidity
Primary Function of Hemoglobin
Delivery and release of oxygen to the tissues
Facilitation of carbon dioxide
Hemoglobin weight in RBC
33% of RBC by volume
95% of RBC dry weight
Male Hemoglobin Normal Range
14-18 g/dL
Female Normal Hemoglobin Range
12-16 g/dL
Infant Normal Hemoglobin Range
14-22g/dL
What does hemoglobin consist of?
4 heme rings + 4 iron molecules + 4 globin chains
Hemoglobin synthesis starts in nucleated RBC stage
Hemoglobin synthesis is dependent on:
- Synthesis of protoporphyrins (precursor of heme)
- Adequate iron delivery and supply
- Adequate globin synthesis
65% occurs during nucleated (immature) RBC stages
35% occurs during polychromatophilic erythrocyte / reticulocyte stage
1 heme ring =
1 porphyrin = 4 pyrrole rings
Primary hemoglobin structure
number and sequence of amino acids in each globin chain
secondary hemoglobin structure
twisting of the amino acid chain (2D helical)
Tertiary hemoglobin structure
bending the twisted amino acid chains into 3D shape (pretzel shape)
Quartenary hemoglobin structure
Assembling each 3D chain with heme groups
Complete, functional hemoglobin molecule
Hemoglobin A1
2 alpha + 2 beta
Most abundant → 95-98%
Hemoglobin A2
2 alpha + 2 delta
2-5%
Hgb F
2 alpha + 2 gamma
Fetal hemoglobin
Less than 2%
Abnormal hemoglobin - unable to carry oxygen
- MetHemoglobin
- Carbocyhemoglobin
- Sulfhemoglobin
MetHemoglobin
- Iron is. oxidized to Ferric State (Fe3+) → no longer binds oxygen
- Reversible through strong reducing substance administration
- Example Causes: ingestion of strong oxidant drug/enzyme deficiency
Carboxyhemoglobin
- Oxygen is replaced with carbon monoxide (CO) → binding is x200 stronger
- Reversible through inhalation → oversaturate blood with oxygen
- Example causes: car running in garage
Sulfhemoglobin
- Sulfur is incorporated into heme structure
- Irreversible
- Example Causes: Ingestion of sulfur containing drugs/ chronic constipation
90% of RBCs energy (ATP) comes from
Non-oxidative pathways.
Even through it carries oxygen to other cells to be used for energy
3 phases of Erythrocyte lIfe
- Erythropoiesis of RBC production
- Release from marrow to circulation
- Destruction and death
Reticuloendothelial System (RES)
Cellular and immunologic defense system in the body → detects if something is wrong in RBC
Phagocytic cells (Histocytes, monocytes, macrophages) in → spleen, liver, lymph nodes, bone marrow
Helps to remove RBC’s from circulation
Primary site of RBC phagocytosis
spleen
Spleen - Home to littoral cells
most sensitive detectors for RBC abnormalities
- Example of RBC abnormalities →
- Senescent (old), nearing 120 life span → membrane loses deformability and elasticity
- Abnormal RBC morphologies and inclusions
- RBC coated in antibodies
Additional function → sequestering (separately storing) ⅓ platelets and granulocytes
Removal of inclusions is called
pitting
removal of RBC from circulation is called
culling
RBC destruction and contents released
Hemolysis
RBC hemoglobin is broken down into
- Fe molecule - put back into plasma iron pool (reused)
- Globin - degraded for protein to amino acid (reused)
- Polyphyrin (heme) ring - has to be metabolized by the body to an excretable form (not reused)
Extracellular Hemolysis
RBC broken w/i RES system
90% of RBC destruction under normal conditions
Intracellular hemolysis
RBC lyses in blood vessel
10% of RBC destruction under normal conditions
How does extracellular hemolysis work
Extra vascular hemolysis process (slide46/53)
Within RES
- Heme disassemble to Biliverdin
- Biliverdin converted to Unconjugated Bilirubin aka indirect Bilirubin
Released to blood and carried by albumin to liver
Within hepatocyte of liver
- Unconjugated Bilirubin is conjugated → Conjugated Bilirubin “Direct Bilirubin”
Urobilinogen then
- is eliminated in the stool
- Reabsorbed into blood and excreted by the kidneys in urine
Intravascular Hemolysis Process ( slide 57/53)
Hemoglobin Released in blood vessel
- Circulates → Hemoglobinemia
- Filtered at the kidney → Haptoglobinuria
- Carried by Haptoglobin to Liver
- Proceeds with extravascular hemolysis
- Gets oxidized to methmoglobin
- Globin seperates
- Metheme
- Stays together and binds abumin - Methemalbumin and carried to liver
- seperates
-
Hemopexin carries heme to liver
- iron is recycled
-
Hemopexin carries heme to liver
- seperates
- Stays together and binds abumin - Methemalbumin and carried to liver
Erythropoiesis is sustained in a steady state
Equal amounts of red cell production and destruction daily
Both equal about 1%
Erythropietin
When less oxygen is being delivered to the kidneys (EPO) is being released. It is a hormone that goes to bone marrow and produces more RBC
When do we need more RBC?
in increase in oxygen demand / decrease in oxygen tension
ex: blood loss / anemia / high altitudes
If the bone marrow cannot keep up with RBC needs
Hematopoiesis starts to occur elsewhere (ex: liver and spleen) → Extra-medullary Hematopoiesis
Hormonal influences that decrease Erythropoiesis
When these are low → low erythropoiesis
- Hypopituitarism
- Hypothyroidism
- Hypoadrenalism (Addison’s Disease)
Hormonal influences that Increase Erythropoiesis
When these are high → high RBC production
- Hyperadrenalism (Cushings disease)
- Increased estrogen
- Increased androgens