Structure and Function of Blood Cells (Strom) Flashcards
Describe the process of looking at blood cells with a microscope.
- Get blood
- Put in a tube with EDTA to keep it from clotting
- Put a drop of it on a slide
- Use another slide to spread the clot out
- let it dry
- Stain (with “wright-giemsa” stain)
Describe the properties and components of the wright-giemsa stain.
- Eosin is the main component and is aromatic/acidic/negatively charged.
- It is soluble in ethanol NOT H2O.
- Stains hydrophobic and basic macromolecules (i.e. Hgb)
What is a variants of eosin-Y that is capable of binding to amine groups for use with flow cytometry?
FITC (fluorescein isothiocyanate)
What cells are rare in peripheral blood (<5% of leukocytes) and are elevated in the context of allergic reactions and infections with parasites?
eosinophil
In what context do the numbers of eosinophils increase in number?
allergic reactions and infection with parasites
What cell type is identified with methylene blue staining?
basophil
Describe the properties of methylene blue stain.
- aromatic and basic
- soluble in water or methanol
- stains hydrophobic acidic macromolecules (i.e. nucleic acids)
What cells are rare in peripheral blood (<1% of leukocytes) and degranulates in allergic reactions?
Basophil
What other cell are basophils related to?
tissue mast cells
What cell types binds little of eosin or methylene blue?
neutrophils
What color do the cytoplasmic granules of neutrophils stain?
light pink
What is the life span of a neutrophil?
<1 day
Normally, neutrophils make up __-__% of leukocytes but can increase ___ fold during infections.
40-70%; 10 fold
What are NETs?
neutrophil extracellular traps: the chromatin of dead neutrophils kill pathogens and can assist in controlling sepsis *also may contribute to sepsis-assc conditions like pre-eclampsia
Knowing the __(cell type)__ count is essential in evaluating any infectious disease.
Neutrophil
What are the mechanisms that neutrophils use as weapons/tactics?
Phagocytosis, degranulation, NETs
What mediator do neutrophils secrete which can lyse bacteria?
lysozyme
How can a monocyte be distinguished from a lymphocyte on a smear?
monocytes often have bent or ameboid nuclei while the nuclei of lymphocytes is more round
Monocytes are ___-___% of blood leukocytes.
3 to 8%
T or F: All macrophages in tissues are derived from monocytes.
F: most but not all
What is the role of monocytes?
phagocytose and present Ag on MHC class II to lymphoctes (which is usually done in the lymphatic system)
Lymphocytes are ___-___% of lood leukocytes.
20 to 30%
What is the life span of a lymphocyte?
days to years
What are the types of lymphocytes and which one is more predominant
T cells > #s B cells and NK
How are reactive lymphocytes distinguished from resting lymphocytes? From monocytes?
reactive more cytoplasm and more prominent nucleoli
get a pathologist or hematologist
What is the life span of a platelet?
9-10 days
What are the 4 functions of platelets listed in lecture?
- form primary hemostatic plug (aggregation)
- stimulate coag cascade to form fibrin clot
- wound healing by simulating fibroblast growth and migration
- Ag presentation
What are the neutrophil variants seen in bacterial infections?
- left shift (inc in immature forms)
2. inc cytoplasmic granules
What are the lymphocyte variations seen with infection?
Reactive forms (larger nuclei and more cytoplasm) **which is seen in many viral syndromes
What are the 7 RBC design requirements?
- flexible shape
- durable membrane
- max Hgb/O2 carrying capacity
- offset osmotic pressure
- Anti-oxidant system
- energy supply
- tune down complement
Describe the shape of RBCs.
flexible biconcave disc with 360 degree fold capacity
What is the lifespan of a RBC?
100 days
Why is the RBC membrane so durable?
They have intracellular cytoskeleton made of spectrin (alpha and beta chains dimers) which interacts with ankyrin, a protein found on the inner leaflet of membrane. This interaction increases the durability of RBC membrane
Mutations in the RBC spectrin reinforced membrane can result in ____ or _____ shapes
spherical or ellipsoid
**also leads to anemia bc RBCs are destroyed from lack of membrane integrity
How do RBCs maximize O2 carrying capacity?
eliminate dead weight organelles like nuclei and pack as high of a conc as Hgb as possible that does not cause Hgb to ppt
What can cause Hgb to ppt?
- too high of a Hgb conc
- minor changes to amino acid sequence
- oxidative damage
**when Hgb ppts it causes lysis
What are consequences of the fact that Hgb is a terrific bacterial growth medium?
bac can enter RBC or the bac can lyse RBCs
How do RBCs offset osmotic pressure?
pump out Na+ out of cell via Na/K pump
*uses ATP
What is the net plasma conc of Na and K?
144 mM (140 mM from Na and 4mM from K)
What is the net intracell conc of Na and K?
111 mM (11mM from Na and 100mM from K)
Describe the anti-oxidant sys in RBCs.
GSH removes H2O2 by allowing H2O2 to oxidize it rather than the Hgb.
GSH –> G-SS-G
The disulfide bond can be removed with reductase and NADPH
T or F: The Anti-oxidant system in RBCs requires energy in the form of ATP.
F: energy in the form of NADPH
G-SS-G + NADPH –> GSH + NADP
Why do RBCs use anaerobic respiration?
bc if they used O2 to make its energy it would consume the O2 that it is supposed to be transporting
Do RBCs have mitochondria?
No
RBCs use __(pathway)__ to make NADPH
pentose shunt
What is the first enzyme in the pentose shunt (used to make NADPH)?
glc 6 phosphatase DH
Describe how RBCs are able to tune down complement fixation.
have DAF on surface to block alternative pathway (both C3 convertase and MAC formation)
What are examples of RBC morphological variants?
- not enough Hgb = hypochromatic and/or microcytic
- residual mRNA
- precipitated Hgb
- Schistocytes
What is anisocytosis?
abnormal RBC sizes (from not enough Hgb)
What is poikilocytosis?
abnormal RBC shapes (from not enough Hgb)
What is hypochroma?
lack of color/lack of Hgb detected by eosin
What is polychromasia?
RBCs with excess residual mRNA and therefore shows up bigger and having a bluish tinge with methylene blue stain.
What does polychromasia indicate?
pt is making a lot of RBCs (probably bc they are losing a lot of them somehow)
What can cause precipitated Hgb?
-genetic defect in Hgb structure-oxidized Hgb
How are bite cells formed?
tissue based phagocytes try to repair oxidized/precipitated Hgb which results in chunks of the cell being removed
What are bite cells suggestive of? (what deficiency)
G6PD deficiency (bc a defect in G6PD is a defect in the anti-oxidant system –> disulfide bonds formed –> ppt of Hgb –> macrophages remove ppt Hgb)
How are schistocytes formed?
- due to mechanical lysis
- microangiopathic processes
- fibrin laces vessels and RBCs get cut into fragments ***these 3 might all be considered the same thing…
T or F: Bite cells and schistocytes are different terms describing the same phenomenon.
F: they look similar but are not the same thing
What is the supernatent of unclotted blood called?
plasma
What is the supernatant of clotted blood called?
serum
Lab testing of clotting methods is performed on (plasma or serum)
plasma
What does hematocrit measure?
the % of blood volume occupied by RBCs
How is hematocrit measured?
RBC volume / total blood volume
What does the hemocytometer measure?
manual measure of white cells and platelets
What does the simple spin hematocrit measure?
manual measure of red cells and Hgb
How are Hgb levels measured currently?
With a hematology analyzer’s spectrophotometer. Cyanide generates a blue color when mixed with Hgb which the spectrophotometer measures
What are reticulocytes?
immature RBCs (inc reticulocytes, think polychromasia)
How are reticulocytes measured?
spectrophotometry with methylene blue added which reacts with mRNA**this measures how well pt is able to compensate
Describe a Coulter chamber
A small container of fluid placed in a larger container of the same fluid. The small container has a tiny opening thru which fluid is pumped at a very precise rate into the larger container –> hole –> small container –> waste container
When a direct current is added to the Coulter chamber, what is measured?
peak number = cell count
peak height = cell volume
When an alternating current is added to the Coulter chamber, what is measured?
peak height = cell complexity (lobular nuclei)
What are all the values that a hematology analyzer measures?
Hemoglobin red cell count (RBC) Mean red cell volume (MCV) Red cell distribution width (RDW) Platelet count Mean platelet volume (MPV)
What is the mean red cell volume indicate?
size of RBC = if the cells have too much or no enough Hgb
Why is the hematocrit value less precise measure of Hgb?
the value can be altered by lab artifacts, drugs, or various disease states
Hemoglobin X 3 =
hematocrit
If the CBC does not match the reported hematocrit, you should use the _____ to decide how anemic the pt is. In this instance, what is abnormal and why?
hemoglobin
MCV (mean red cell volume) is abnormal due to artifacts such as red cells clumping or due to a disease
How are white cells measured exclusively? What is a limitation of this test?
- mix blood sample with soln that lyses red cells (isotonic ammonium chloride)
- run thru coulter chamber
- diff leukocyte population show up on diff locations in graph produced
limitation = eosinophils and basophils are not well separated from other populations
How are baso and eosinophils seperated out from the rest of the population of white cells for measurement?
use the flow cytometer before the coulter chamber to seperate them from neutrophil population *adds measurement of complexity to do this
How does a flow cytometer work?
laser in flow cytometer measures forward scatter to measure cell size/shape*used to differentiate baso and eosinophils from neutrophils
How are immature platelets measured (immature platelet fraction , IPF)?
using flow cytometry to detect excess mRNA
What does an increase in IPF indicate?
pt is compensating for decreased platelet number
Per ul, how many platelets are consumed each day?
7000 per ul (11%)
The IPF will go (up or down) in pts whose thrombocytopenia is due to impaired function.
up (3x normal)
Are linear or exponential platelet turnover rates normal?
linear is normal and exponential and abnormal (thrombocytopenic)
What can the hematology analyzer NOT count reliably?
- bands
- blasts (may be counted as lymphocytes or monocytes)
- red cell fragments (counted as platelets)-platelet clumps (can get artificial thrombocytopenia)
What is found in peripheral blood smear that can indicate acute leukemia?
blasts
