Hematology Exam 2 Flashcards
What is an erythroblast?
Nucleated RBC precursor restricted to the bone marrow
BFU-E gives rise to _____ colonies.
CFU-E gives rise to _____ colonies.
Which is more immature?
Large; Smaller
BFU-E is more immature
List the order of maturation of RBCs from BFU-E to mature erythrocyte.
BFU-E –> CFU-E –> Pronormoblast –> Basophilic normoblast –> Polychromatic normoblast –> Orthochromic normoblast –> polychromatic RBC (reticulocyte) –> Erythrocyte
What are the 5 rules of RBC maturation?
- Size of cell decreases as it matures
- N:C ratio decreases as it matures (eventually nucleus is gone)
- Nuclear chromatin condenses
- Nucleoli disappear
- Cytoplasm changes from blue to gray-blue to pink
Why does an immature RBC have a blue cytoplasm, while a mature RBC has a pink cytoplasm?
Blue color correlates with RNA presence, and pink color correlates with amount of hemoglobin present. Younger cells are more active in protein production and as they age, ribosomes disappear and only hemoglobin remains.
Standout features of PRONORMOBLAST identification
- HUGE round nucleus (8:1 N:C ratio) with purple/red open chromatin
- Dark blue cytoplasm with golgi complex possibly visible as unstained area
Standout features of BASOPHILIC NORMOBLAST identification
- chromatin begins to condense and is more purple
- nucleus begins to get smaller, but still large (6:1 N:C ratio)
- cytoplasm is more of a deeper blue color
Standout features of a POLYCHROMATIC NORMOBLAST identification
- No nucleoli present, N:C ratio greatly decreases (4:1-1:1)
- Cytoplasm becomes more of a pink-blue color
What is the last stage of RBC precursor that is capable of division?
Polychromatic normoblast
Standout features of ORTHOCHROMIC NORMOBLAST identification
- Completely condensed chromatin and small nucleus (1:2 NC ratio)
- Increasing pink color in cytoplasm
- looks like a “fried egg”
Is it normal to see polychromatic erythrocytes (reticulocytes) in peripheral blood?
It is ok to see them, just not a lot of them. If you see too many, that is indicating a problem.
Where are reticulocytes found?
BM for 1-2 days and then peripheral blood for ~1 day before reaching maturity.
Is it normal to see nRBCs in the peripheral blood?
NO. These should only be found in the bone marrow.
Standout features for POLYCHROMATIC ERYTHROCYTE/RETICULOCYTE identification
- NO nucleus (first stage that is NOT an nRBC)
- Pink cytoplasm with blue tinge around edges
- Can see blue RNA in supravital stain
- NOT a biconcave disk; irregular shape
Standout features of a MATURE ERYTHROCYTE identification
- no nucleus
- biconcave disk, salmon-pink color with central pallor
- located in peripheral blood/circulation
What organ produces erythropoietin (EPO)?
Kidneys
What is the function of erythropoietin?
The major stimulatory cytokine for RBCs; acts as a hormone and a growth factor for developing erythroid cells
What organ is hypoxia detected by? What does this trigger?
Detected by kidneys; triggers EPO production
What stimulates EPO release?
Low oxygen detected by kidneys (hypoxia)
What are the 3 major effects of erythropoietin?
- Allows early release of reticulocytes from the bone marrow
- Prevents apoptosis
- Reduces the time needed for cells to mature in the BM (accelerates hemoglobin production)
What is a shift reticulocyte?
Very basophilic, young reticulocytes that have been released from the BM early due to trigger from EPO
What is extravascular hemolysis vs intravascular hemolysis?
Extravascular hemolysis occurs in the spleen and is macrophage-mediated. It is good, controlled destruction of RBCs.
Intravascular hemolysis is mechanical when a small portion of RBCs rupture intravascularly and results in fragmentation of RBCs.
Name the products of the Glycolysis pathway from Glucose –> Lactate in order. (using abbreviations)
Glucose
G6P (Glucose-6 Phosphate)
F6P (Fructose-6 Phosphate)
F1,6-BP (Fructose 1,6-Bisphosphate)
G3P (Glyceraldehyde-3 Phosphate)
1,3-BPG (1,3-Bisphosphoglycerate)
3PG (3-phosphoglycerate) - 2 ATP produced here
2PG (2-phosphoglycerate)
PEP (phosphoenolpyruvate)
Pyruvate - 2 ATP produced here
Lactate
What enzyme takes Glucose to G6P?
Hexokinase
What enzyme takes G6P to F6P?
G6P isomerase
What enzyme takes F6P to F-1,6 BP?
6-PFK
What enzyme takes F1,6-BP to G3P
FBP aldolase
What enzyme takes GA3P to 1,3 BPG?
GA3P dehydrogenase
What enzyme takes 3PG to 2PG?
phosphoglycerate mutase
What enzyme takes 2PG to PEP?
Enolase
What enzyme takes PEP to pyruvate?
Pyruvate kinase
What enzyme takes pyruvate to lactate?
Lactase dehydrogenase
In what two steps in the glycolytic pathway do we gain our four ATP?
1,3 BPG to 3PG +2 ATP
PEP to Pyruvate +2 ATP
What is the net gain of ATP in the Embden-Meyerhof Pathway per one molecule of glucose?
2 ATP. We make 4 ATP in the process, but we use 2 ATP in the process.
Through which transmembrane protein does glucose enter the RBC?
Glut-1
What is the initial substrate of anaerobic glycolysis?
Glucose
What are the final products of anaerobic glycolysis?
Pyruvate, ATP, Lactate, NAD
What is the main purpose of the Hexose Monophosphate Pathway/Shunt?
detoxification of peroxide - uses 5-10% of G6P from embden-meyerhof pathway to divert to this pathway
What is the main purpose of the Methemoglobin Reductase pathway?
Formed methemoglobin’s ferric iron (Fe3+) is reduced to ferrous iron (Fe2+) to be in oxygen carrying state
What is the purpose of the Rapoport-Leubering Pathway? What is the downfall of this pathway?
Makes 2,3-BPG to increase oxygen delivery to tissues.
The downfall is that you do not make 2 ATP in this process, so there is an ATP deficit in the cell
What are the principal cytoskeletal proteins if the RBC membrane?
alpha-spectrin and beta-spectrin
What are the principle transmembrane proteins on RBC membranes?
Blood group antigens, GPI anchor, PNH
Which substances is the RBC membrane permeable to?
Water, anions HCO3- (bicarbonate) and Cl- (chloride)
What substances is the RBC membrane impermeable to?
cations Na+, K+, Ca2+
Mononuclear cells include?
Monocytes and lymphocytes
Polymorphonuclear cells include?
Neutrophils, basophils, and eosinophils
List the two progenitor cells from which leukocytes can arise:
Common myeloid progenitor cells and common lymphoid progenitor cells
List the order of maturation for myeloid precursors from blast to segmented neutrophil
Myeloblast –> Promyelocyte –> Myelocyte –> Metamyelocyte –> Band neutrophil –> Segmented neutrophil
What is a standout feature of a MYELOBLAST that will help you identify it?
High N:C ratio 8:1
Slightly basophilic cytoplasm with fine nuclear chromatin
2-4 nucleoli
What is a standout feature of a PROMYELOCYTE that will help you identify it?
- LARGEST precursor cell
- oval, off-centered nucleus
- full of primary granules in cytoplasm (large, dark purple, abundant)
What is a standout feature of a MYELOCYTE that will help you identify it?
- “dawn of neutrophilia” - patches of grainy pale pink cytoplasm representing production of secondary granules
- early myelocytes similar in size to promyelocytes, later myelocytes become smaller and cytoplasm becomes lavendar-pink showing presence of secondary granules; primary granules less visible
- nucleus similar in size/shape to promyelocytes
What is a standout feature of a METAMYELOCYTE that will help you identify it?
- indented, kidney bean shaped nucleus with no nucleoli
- little to no basophilia due to production of tertiary granules
- increasingly clumped chromatin
- slightly smaller than myelocyte
What is the first stage of neutrophil precursors that is no longer capable of division?
Metamyelocytes
What is a standout feature of a BAND NEUTROPHIL that will help you identify it?
- indentation of nucleus that exceeds 1/2 the diameter of the nucleus but is not yet segmented
- no basophilia; tertiary granules present
- highly clumped chromatin
- FIRST STAGE THAT IS OK TO SEE IN PERIPHERAL BLOOD (0-5%)
What is the first stage of neutrophil development that is OK to see in peripheral blood? What percentage is normal?
Band neutrophils; 0-5%
What is a standout feature of a SEGMENTED NEUTROPHIL that will help you identify it?
- presence of 2-5 nuclear lobes connected
What is the normal % of seg neutrophils in the blood?
50-70%
What is diapedesis?
process by which neutrophils leave the blood and enter the tissues
What is the major function of neutrophils?
phagocytosis and destruction of foreign material
List the steps of extravasion/diapedesis of a neutrophil
- ROLLS along endothelial cells
- ADHERES to endothelial cells
- CRAWLS towards site of transmigration
- TRANSMIGRATES between endothelial cells
List the steps of phagocytosis
- RECOGNITION of foreign material
- ATTACHMENT to foreign material
- ENGULFMENT of foreign material
- release of granular content to KILL foreign material
- DIGESTION of foreign material
What is the % of eosinophils in the blood?
1-3%
Why might eosinophils be elevated in the blood?
allergic reaction or parasitic infection
Function of eosinophils
Important role in immune regulation; capable of acting as APCs; regulate mast cell function
Normal % of basophils in the blood?
0-2%
What are basophils morphologically and functionally similar to?
Mast cells
What is the least numerous WBC?
Basophils
What is the role of basophils?
Control of helminth infections; Initiate allergic inflammation through release of cytokines
What 3 main WBC are considered granulocytes?
Basophils, eosinophils, and neutrophils (PMNs)
What is the normal % of monocytes in the blood?
2-11%
Which WBC has a “ground glass” appearance?
Monocyte
What 3 cells can monocytes differentiate into?
Macrophage
Osteoclasts
Dendritic cells
What is the function of monocytes/macrophage?
Play a role in innate and adaptive immunity and housekeeping functions
What are the 3 major groups of lymphocytes?
T cells, B cells, and NK cells
What is the normal % of lymphocytes in the blood?
18-42%
What are hematogones?
immature B cells found in secondary lymphoid organs
What is the major difference between B cell lymphs and T cell lymphs?
T cells mature in thymus
B cells mature in bone marrow
B lymph functions?
antibody production
T lymph functions? (differentiate between CD4T cell function and CD8T cell function)
CD4 are T helper cells that mediate immune responses against pathogens
CD8 are cytotoxic T cells that kill target cells
NK lymph functions
kill tumor cells or virus-infected cells
List the order of maturation for platelets from CFU-GEMM to platelets
CFU-GEMM –> Megakaryoblast –> Promegakaryocyte –> Megakaryocyte –> Platelets
What is endomitosis? Which BM cell undergoes this process?
a form of mitosis that lacks telophase and cytokinesis (separation into daughter cells) - Light Density CFU undergoes endomitosis
What are the 3 megakaryocyte committed progenitor stages?
BFU-Meg - mitosis to form hundred of colonies
CFU-Meg - mitosis to form dozens of colonies
Light Density CFU - endomitosis
Common myeloid progenitors become megakaryocyte progenitors under the influence of _______?
GATA-1
What is MK-1? Describe what it contains
Megakaryoblast that have plasma membrane blebs, alpha granules, dense granules, and DMS present
What is MK-II?
Promegakaryocyte
What is MK-III?
Megakaryocyte - most abundant stage
Describe the steps of platelet shedding (thrombocytopoiesis)
- DMS dilates
- tubules form
- proplatelet processes develop
- processes pierce through endothelial cells into venous blood
- constrictions appear throughout processes
- platelets are broken off
What cytokines support megakaryocytopoiesis?
Thrombopoietin (TPO), Stem cell factor, IL-3, IL-6, IL-11
What cytokines INHIBIT megakaryocytopoiesis?
PF-4
Beta-thromboglobulin
Neutrophil activating peptide 2
IL-8
How much of the platelets in the body does a platelet count represent? Where are the rest?
2/3; the other 1/3 are sequestered in the spleen
what is the normal PLT count?
150-400 x 10^9/L
What is a thrombocyte vs a reticulated platelet?
Thrombocyte is the term for platelet.
A reticulated platelet is a stress platelet that appears in compensation for thrombocytopenia (low platelet count)
Outer phospholipids of PLT membrane
phosphatidylcholine and spingomyelin
Inner phospholipids of the PLT membrane
Phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine
What PLT granules release their contents into the SCCS?
Alpha granules
What are the 3 steps of PLT activation (describe them)
- Adhesion - PLTs bind to other things
- Aggregation - PLTs bind to eachother
- Secretion - release granular contents