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Hematology Exam I

Terms in this set (134)

What is the average volume of blood in humans?
5 L
What are four major functions of blood?
1. transport o2 and nutrients
2. forming blood clots to prevent blood loss
3. transport WBCs and antibodies for immunity
4. bring waste products to liver and kidneys
What term is used to describe the liquid (noncellular) portion of blood in the body?
plasma
What are the three basic cellular elements in blood? (State their common and scientific names.)
1. RBCs (erythrocytes)
2. WBCs (leukocytes)
3. PLTs (thrombocytes)
Briefly describe both the structure and the function of RBCs.
STRUCTURE : nonnucleated, biconcave discs filled with reddish protein called hgb. 6-8 microns in diameter

FUNCTION : transport o2 and nutrients to cells/tissues. transport glucose, fat, proteins. move wastes to liver and kidneys.
What is the microscopic appearance of RBCs when stained with a Romanowsky stain?
aka wright's stain. appear salmon in color
What aspects of RBCs are described when their morphology is described?
size, shape, color, pallor
What is the meaning of the term anemia?
loss of O2 carrying capacity usually by loss of RBCs
What is the meaning of the term polycythemia?
elevated RBC count
What saline concentration provides the ideal osmolality for the study of RBCs?
0.85%
What is a hemocytometer? Describe how this device is used in hematology.
device used to estimate blood cell counts under microscope
What is the name of the key reagent used to measure hemoglobin? What is its composition?
drabkin's reagent ; weak solution of potassium cyanide and potassium ferricyanide
What is an alternate term for hematocrit?
packed cell volume (PCV)
What phenomenon does the term buffy coat describe?
thin, white layer formed b/w RBCs and serum/plasma after centrifugation and contains WBCs, platelets
What phrases are represented by each of the following abbreviations: MCV, MCH, MCHC, and RDW?
MCV - mean cell volume
MCH - mean cell hemoglobin
MCHC - mean cell hemoglobin concentration
RDW - RBC distribution width
What characteristic of the RBC population is described by the MCV?
average cell volume of RBCs
expressed in fL
ref range 80-100
low - microcytic
high - macrocytic
What characteristic of the RBC population is described by the MCHC?
average hgb concentration in RBCs
expressed in g/dL
ref range 32-36
low - hypochromic
high - hyperchromic
What characteristic of the RBC populations is described by the RDW?
degree of variability of cell sizes in RBC population
elevation = anisocytosis
What is the appearance of immature RBCs on Wright-stained blood films?
blue/gray
What is meant by the term polychromatophilic as used to describe erythrocytes?
synonymous with reticulocytes
What is the function of the stain used to differentiate and count reticulocytes?
to indicate function of bone marrow
Why are white blood cells (WBCs) referred to as white?
because WBCs are nearly colorless microscopically before staining
What is the purpose of using dilute acetic acid as a reagent when counting WBCs?
lyse RBCs to make WBCs more visible
What is an approximate normal range for the WBC count?
3.6-10.6 (10^3 uL)
What abnormal condition is represented by the term leukopenia?
decreased WBCs
What abnormal condition is represented by the term leukocytosis?
increased WBCs
What term is often used to represent PMNs?
polymorphonuclear neutrophils. segmented neutrophils
What abnormal condition is represented by the term neutropenia?
decreased neutrophils
What underlying abnormal conditions may induce neutropenia?
viral infection ; long term medication use
What abnormal condition is represented by the term neutrophilia?
increased neutrophils
What underlying abnormal conditions may induce neutrophilia?
bacterial infection
What is the primary physiologic function of PMNs?
phagocytosis of pathogens
What term is often used to represent band neutrophils?
bands
What is the relationship of band neutrophils to PMNs?
immature neutrophils
What is the relationship of band neutrophils to the left shift?
left shift means elevated bands
What are two key morphologic features of eosinophils on Wright-stained blood smears?
tan/orange in color
defined granules
What is the primary component of the granules of eosinophils?
antihistamine
What abnormal condition is represented by the term eosinophilia?
increased eosinophils
What underlying abnormal conditions may induce eosinophilia?
allergy response and parasitic infection
What are two key morphologic features of basophils on Wright-stained blood smears?
dark blue/purple in color
dark granules obscuring nucleus
What are the key morphologic features of lymphocytes on Wright-stained blood smears?
dark, round, featureless nucleus. thin, irregular cytoplasmic rim. slightly larger than RBC
What is the primary physiologic function of lymphocytes?
provide adaptive immunity
What abnormal underlying condition or conditions may cause lymphocytosis?
viral infections
What abnormal underlying condition or conditions may cause lymphopenia?
drug therapy or immunodeficiency
What is the relationship of monocytes to macrophages?
immature macrophages
What are the key morphologic features of monocytes on Wright-stained blood smears?
larger than other WBCs, lobulated nucleus, gray/purple color
What is the most fundamental physiologic function of platelets?
form blood clots
What are the key morphologic features of thrombocytes on Wright-stained blood smears?
small 2-4 micrometers diameter, anucleate, slightly granular
How is the performance of a manual platelet count similar to the performance of a manual WBC count?
both are counted on hemacytometer
How is the performance of a manual platelet count different from the performance of a manual WBC count?
more PLTs need to be counted ; difficult to distinguish b/w dirt/debris ; not as accurate due to high count and hard to distinguish
What is the significance of an elevated mean platelet volume (MPV)?
large platelets which is indicative of several different conditions
What are the defining characteristics of essential thrombocythemia?
bone marrow makes too many platelets resulting in abnormal clotting (can be over clotting or under clotting). can cause strokes, heart attacks, and can progress to leukemia
Why might essential thrombocythemia be life threatening?
can cause strokes and heart attacks
What is thrombocytopenia? Why might it be life threatening?
low platelets ; can result in internal hemorrhage
What are some specimen collection errors that will produce false complete blood count (CBC) results?
clotting, hemolysis, short draws
What happens to a laboratory specimen when it is accessioned?
specimen is inputted into LIS, usually a work list. usually automated through barcode scanning to limit pre-analytical errors
What does term flagged indicate on a CBC instrument?
med tech needs to review flagged value as it may require further investigation and recollect. may reflex to blood film examination
What steps are included in the performance of a WBC differential?
count 100 WBCs to determine percentage of different WBCs present
Where are endothelial cells located? What are some of their important blood-related functions?
line inside of blood vessels ; promote normal blood flow, anchor platelets when clot formation is needed, allow WBCs to exit vessels to surrounding tissues when needed
What are the two most fundamental components of hemostasis?
platelets and coag factors
What are the function and the key components of the coagulation system?
to form fibrin clots in order to plug tears in blood vessels to stop hemorrhage. key components include platelets and coag factors
What is the function of fibrinolysis?
to digest fibrin clots
What are five minor blood specimen defects that may render it useless for coagulation laboratory assays?
1. clots
2. hemolysis
3. short draws
4. icteric (bilirubin)
5. lipemia
What are the names of two coagulation assays that are described as high volume because they are so frequently performed?
1. PT/PTT
2. heparin
What are some examples of assays that are less frequently performed in coagulation laboratories?
fibrinogen, mixing studies, lupus anticoag, d-dimer
What are four examples of advanced hematologic procedures most often performed only in larger hospitals and specialty laboratories?
1. bone marrow examinations
2. flow cytometry
3. molecular diagnostics
4. cytogenetic assays
What are two types of bone marrow samples collected for analysis in the hematology laboratory?
aspirate, biopsy
What generic scientific adjective is used to describe bone marrow cells that are precursors to RBCs?
erythroid series
What generic scientific adjective is used to describe bone marrow cells that are precursors to monocytes, PMNs, and other granulocytes?
myeloid series
What bone marrow cell type produces platelets?
megakaryocytes
What is the null hypothesis? How does this differ from the alternative hypothesis?
null hypothesis states there is no correlation b/w the two variables being compared. alternative hypothesis is the logical opposite of the null hypothesis, stating there is a difference b/w the two variables.
What is the p scale range, and what does it represent?
...
State the conventional levels for significance (rejecting the null hypothesis).
...
What is the formula for calculating the arithmetic mean?
mean = sum of terms/number of terms
How is the median value of a sample set identified?
terms are put into numerical order and then eliminated until center term is identified. if two terms left, find mean of two remaining terms.
What is the mode? How is the mode of a data series determined?
mode is the term repeated the most out of all terms
What is the variance and how is it calculated?
expressed deviation of each data point from its expected value.
What is the standard deviation (SD)?
measure of dispersion ; square root of all variances ; mean distance of all data points from the sample mean
State the acceptable SD limits for establishing biologic reference intervals (normal ranges).
...
What is the formula for the coefficient of variation (CV%)?
(SD/mean)*100
What procedures are included in a validation study?
...
What is the definition of accuracy? How do accuracy and precision differ?
accuracy is how close the data is to the expected true value. precision is the reproducibility of results. an assay may lack accuracy but still have precision if their results are close together.
What is a primary standard?
has a known, fixed composition in the purest form. used in QC
How does a secondary standard differ from a primary standard?
purchased fixed specimen that has a known concentration, usually bought through the vendor. ***
How are calibrators prepared and used in the clinical laboratory?
...
The cell membrane is defined as semipermeable and selectively permeable. To what substances is it permeable and to what ones is it impermeable?
the cell membrane is able to selectively regulate what substances passes through the membrane ****
What are the four most basic functions of the cell membrane?
1. physical barrier
2. selective permeability
3. establishes electrochemical gradients
4. has receptors to allow cell to respond to outside stimuli
What aspect of cell membrane composition best accounts for its resilience and elasticity?
it is a fluid structure of proteins floating in lipids
What are two very abundant lipids within the cell membrane?
phospholipids and sterols (cholesterol)
What portion of a phospholipid molecule is relatively polar (hydrophilic) and thus oriented toward the inner or outer surface of the membrane's lipid bilayer?
the hydrophilic head of the phospholipid is oriented towards the outside of the bilayer (intracellular and extracellular)
What portion of a phospholipid molecule is relatively nonpolar (hydrophobic) and thus oriented toward the center of the membrane's lipid bilayer?
the hydrophobic tail of the phospholipid is oriented towards the inside of the bilayer
What are two examples of highly complex types of lipid-containing molecules within the cell membrane?
DELETE
What is the difference in structure and location between the transmembrane proteins and the cytoskeletal proteins?
transmembrane proteins span the entire membrane and contain channels leading in/out of the cell. cytoskeletal proteins are only found on the cytoplasm side of membrane and they form a skeletal lattice which provides structural integrity
What general function is shared by many transmembrane proteins?
function as channels to inside/outside of cell
What is the function of cytoskeletal proteins?
to provide structural integrity to the cell membrane
What is the outer cell surface (carbohydrate coat) called?
glycocalax
What are four functions of cell membrane carbohydrates?
1. provide protection
2. cell-to-cell recognition
3. cell-to-cell adhesion
4. provide negative surface charge to repel other cells
What three components make up the nucleus?
chromatin, nucleoi, nuclear envelope
What are the most important cellular activities that take place within the nucleus?
command center of the cell. DNA replication
Why do nuclei generally stain dark with basic dyes?
because of RNA
What is the difference in the stained appearance of heterochromatin and euchromatin?
heterochromatin is more darkly stained, condensed clumping pattern. euchromatin is pale blue and loosely coiled.
What is the difference in molecular activity taking place in euchromatin versus heterochromatin?
heterochromatin is the transcriptionally inactive area of the nucleus while euchromatin is the genetically active area where DNA transcription in mRNA occurs.
What is the relationship between the number of nucleoli in a cell and the amount of protein synthesis taking place at the time it was fixed and stained?
number of nucleoli proportional to protein synthesis. If no nucleoli is present at time of staining, it means no protein synthesis was taking place and it can be assumed the cell is a mature cell.
Which of the cell's organelles has its components synthesized in nucleoli and then exported to the cytoplasm to be assembled?
ribosomes
What descriptive terms can be used to define the cytoplasmic matrix? What is a commonly used synonym for this matrix?
homogenous, continuous, aqueous. cytosol
What is the molecular composition of ribosomes?
small and large units of rRNA and accessory ribosomal proteins
In what cellular locations are ribosomes found?
cytoplasm which gives cells dark blue color when stained
What are polyribosomes?
clusters of ribosomes simultaneously translating the same mRNA
What is the relationship between the abundance of ribosomes in a cell and its protein production levels?
the more ribosomes in a cell correlates to a larger production of protein
What is the relationship between the abundance of ribosomes in a cell and its degree of basophilia on Wright-stained smears?
if a cell is actively producing proteins through ribosomes, they will stain a dark blue color
What is a general description of the location, appearance, and function of the endoplasmic reticulum?
location - adjacent to nucleus and extends into cytoplasm

appearance - membrane bound network of flattened sacs and tubes

function - controls "traffic" or flow of molecules b/w the nucleus and cytoplasm
What additional component makes the rough endoplasmic reticulum appear rough as compared with the smooth endoplasmic reticulum?
RER contains ribosomes
What is a general description of the location and function of the Golgi apparatus?
location - close to RER and nucleus

function - modifying, sorting, packaging macromolecules for secretion or delivery to other organelles
What are the cisternae? What is their function?
flattened sacs that involved in the modifying and packaging
How do mitochondria differ from other cellular organelles in terms of their replication?
are capable of self-replication because they contain their own DNA.
Approximately how many mitochondria are found within individual (prototypical) cells?
as little as 100 to as much as several thousand
Why are some cells far more enriched with mitochondria than others?
the more energy the cell requires, the more mitochondria will be present
What are the most abundant molecules within lysosomes?
hydrolytic enzymes
How does the lysosomal membrane protect other cellular organelles?
prevents enzymes from digesting other parts of the cell
What is the appearance of larger lysosomes in cells on Wright-stained smears?
in WBCs and platelets, appear as granules
State the function of actin microfilaments.
enable cell motility, contraction, and intracellular transport
function of intermediate filaments.
structural stability
Where does hematopoiesis occur?
bone marrow
What is the function of the stromal cells?
secrete substances to form an extracellular matrix which allows for new cell growth and development (anchor)
What is the purpose and function of the extracellular matrix?
provide a place for new and developing cells to anchor
What is the cell cycle?
replicate DNA and distribute equally to two daughter cells
What are the six phases of mitosis?
1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase
6. cytokinesis
What are the four stages of the cell cycle?
1. G1
2. S
3. G2
4. mitosis
What are the two checkpoints or restriction points in the cell cycle?
G1 checkpoint (checks DNA for damage and makes cell wait to repair or induce apoptosis)

S phase checkpoint checks DNA for damage and complete DNA replication

G2 checkpoint verifies no errors in DNA and if there is then mitosis is blocked
What occurs when tumor-suppresser genes are deleted or mutated?
cells with abnormal or deleted DNA will go through cell cycle and replicate which can develop into neoplasms
What is apoptosis?
programmed cell death
What are the two major mechanisms for cell death?
necrosis and apoptosis
What are the typical sources for the initiation of apoptosis?
eliminate harmful cells, cells no longer needed/in excess, aging cells
How does apoptosis appear morphologically?
shrink
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