Overview Flashcards
The average human possesses_____ of blood.
5 liters
Purpose of Blood (4)
transports oxygen from lungs to tissues
clears tissues of carbon dioxide
transports glucose, proteins, and lipids
moves wastes to the liver and kidneys
The liquid portion is_______which, among many components, provides coagulation enzymes that protect vessels from trauma and maintain the circulation.
plasma
Purpose of plasma
provides coagulation enzymes that protect vessels from trauma and maintain the circulation.
transports and nourishes blood cells.
Plasma
There are three categories of blood cells:
red blood cells (RBCs), or erythrocytes
white blood cells (WBCs), or leukocytes
platelets (PLTs), or thrombocytes
Study of blood cells
Hematology
is ordered on nearly everyone who visits a physician or is admitted to a hospital.
complete blood count (CBC)
The first scientists, such as______ in ____, described “worms” in the blood
Athanasius Kircher in 1657
______ in ____gave an account of RBCs
Anton van Leeuwenhoek in 1674
In the late 1800s that______ described platelets as “______”
Giulio Bizzozero
petites plaques
The development of the Wright stain by ______ in ____opened a new world of visual blood film examination through the microscope.
James Homer Wright in 1902
Although automated analyzers now differentiate and enumerate blood cells,_________ stain (polychromatic, a mixture of acidic and basic dyes), and refinements thereof, remains the foundation of blood cell identification.*
Wright’s Romanowsky-type stain
In the present-day hematology laboratory, RBC, WBC, and platelet appearance is analyzed through automation or visually using 500× to 1000x _______examination of cells fixed to a glass microscope slide and stained with______ or _______ stain
light microscopy
Wright or Wright-Giemsa
The scientific term for cell appearance is morphology, which encompasses (5)
cell color
size
shape
cytoplasmic inclusions
nuclear condensation
_____ are anucleate, biconcave, discoid cells filled with a reddish protein,______, which transports _____ and _____
RBCs
Hemoglobin
oxygen and carbon dioxide
RBCs appear _____ (color) and measure______ in diameter with a zone of pallor that occupies one third of their center, reflecting their biconcavity
salmon pink
7 to 8 um
Since before 1900, physicians and medical laboratory professionals counted RBCs in measured volumes to detect_____ or _____
anemia or polycythemia
means loss of oxygen-carrying capacity and is often reflected in a reduced RBC count or decreased RBC hemoglobin concentration
Anemia
means an increased RBC count reflecting increased circulating RBC mass, a condition that leads to hyperviscosity
Polycythemia
Historically, microscopists counted RBCs by carefully pipetting a tiny aliquot of whole blood and mixing it with_______
0.85% (normal) saline
Why is .85% normal saline solution mixed with RBCs?
Normal saline matches the osmolality of blood; consequently, the suspended RBCs retained their intrinsic morphology, neither swelling nor shrinking.
A______ dilution was typical for RBC counts, and a glass pipette designed to provide this dilution, the_____ pipette, was used routinely until the advent of automation.
1:200
Thoma pipette
The diluted blood was transferred to a glass counting chamber called a_____
hemacytometer
The microscopist observed and counted RBCs in selected areas of the hemacytometer, applied a mathematical formula based on the dilution and on the area of the hemacytometer counted, and reported the RBC count in cells per…
microliter (ML, meL, also called cubic millimeter, mm’)
milliliter (mL, also called cubic centimeter, or cc)
liter (L)
Visual RBC counting was developed before 1900 and, although inaccurate, was the only way to count RBCs until_____, when automated particle counters became available in the clinical laboratory.
1958
The first electronic counter, patented in____ by _____ and ______ of Chicago, Illinois, was used so widely that today automated cell counters are often called_____ counters, although many high-quality competitors exist
1953 by Joseph and Wallace Coulter
Coulter counters
The Coulter principle of___________ is still used to count RBCs in many automated blood cell analyzers.
Fortunately, the widespread availability of automated cell counters has replaced visual RBC counting, although visual counting skills remain useful where automated counters are unavailable.
direct current electrical impedance
______measurement relies on a weak solution of potassium cyanide and potassium ferricyanide, called Drabkin reagent.
Hemoglobin
Drabkin reagent.
weak solution of:
potassium cyanide
potassium ferricyanide
HGB conc.
An aliquot of whole blood is mixed with a measured volume of_____, hemoglobin is converted to stable_______, and the absorbance or color intensity of the solution is measured in a spectrophotometer at____ wavelength.°
The color intensity is compared with that of a known standard and is mathematically converted to hemoglobin concentration.
Drabkin reagent
cyanmethemoglobin (hemiglobincya-nide)
540 nm
HGB conc.
Modifications of the cyanmethemoglobin method are used in most automated applications, although some automated blood cell analyzers replace it with a formulation of the ionic surfactant (detergent)______ to reduce environmental cyanide.
sodium lauryl sulfate
______ is the ratio of the volume of packed RBCs to the volume of whole blood
Hematocrit
Hematocrit is manually determined by transferring blood to a plastic tube with a uniform bore, centrifuging, measuring the column of____, and dividing by the total length of the column of_______
RBCs
RBCs + plasma
Hematocrit
The normal ratio approaches____
50%
Hematocrit is also called__________, the packed cells referring to RCs.
packed cell volume (PCV)
Often one can see a light-colored layer between the RBCs and plasma. This is the______
buffy coat
buffy coat contains ______ and _____, and it is excluded from the hematocrit determination.
WBCs and platelets
The medical laboratory professional may use the three numerical results,_____,_____ and ____, to compute the RBC indices mean cell volume (MCV), mean cell hemoglobin (MCH), and mean cell hemoglobin concentration (MCHC)
RBC count, HGB, and HCT
The medical laboratory professional may use the three numerical results, RBC count, HGB, and HCT, to compute the RBC indices…
mean cell volume (MCV)
mean cell hemoglobin (MCH)
mean cell hemoglobin concentration (MCHC)
_____ although a volume measurement recorded in______, reflects RBC diameter on a Wright-stained blood film.
MCV
femtoliters (fL)
The_______, expressed in______, reflects RBC staining intensity and amount of central pallor.
MCHC
grams per deciliter (g/dL)
The_____ in ______ expresses the mass of hemoglobin per cell and parallels the MCHC.
MCH
picograms (pg)
A fourth RBC index,______, expresses the degree of variation in RBC volume.
RBC distribution width (RDW)
Extreme RBC volume variability is visible on the Wright-stained blood film as variation in diameter and is called______.
anisocytosis
The_____ is based on the standard deviation of RBC volume and is routinely reported by automated blood cell analyzers
RDW
RBC distribution width
Medical laboratory professionals routinely use light microscopy at _____ or _____magnification to visually review RBC morphology, commenting on RBC diameter, color or hemoglo-binization, and shape and the presence of cytoplasmic inclus
500X or 1000X
are used in nearly all clinical laboratories to generate these data, although visual examination of the Wright-stained blood film is still essential to verify abnormal results.
Automated blood cell analyzers
Reticulocytes
In the Wright-stained blood film, _____ of RBCs exceed the 7- to 8-mm average diameter and stain______.
0.5% to 2.5%
slightly blue-gray
________ are newly released from the RBC production site: the bone marrow
polychromatic (polychromatophilic) erythrocytes
are closely observed because they indicate the ability of the bone marrow to increase RBC production in anemia caused by blood loss or excessive RBC destruction
Polychromatic erythrocytes
What are used to differentiate and count young RBCs—Reticulocytes
Methylene blue dyes
nucleic acid stains or vital stains
are dyes absorbed by live cells.
Vital (or “supra-vital”) stains
Young RBCs contain ribonucleic acid (RNA) and are called_______ when the RNA is visualized using vital stains
reticulocytes
Counting______ visually by microscopy was (and remains) a tedious and imprecise procedure until the development of automated reticulocyte counting by the TOA Corporation (presently_______) in 1990.
Now all fully automated blood cell analyzers provide a relative reticulocyte percentage, an absolute reticulocyte count, and, in addition, an especially sensitive measure of RBC production, the immature reticulo-cyte fraction
reticulocytes
Sysmex
are a loosely related category of cell types dedicated to protecting their host from infection and injury
WBCs, or leukocytes
WBCs are transported in the blood from their source, usually_____ or ____, to their_____ or _____ destination.
bone marrow or lymphoid tissue
tissue or body cavity
WBCs may be counted visually using a______ and ______.
The technique is the same as RBC counting, but the typical dilution is____, and the diluent is a_______.
microscope and hemacytometer
1:20
dilute acid solution
Why is the diluent for WBCs a dilute acid solution?
The acid causes RBCs to lyse or rupture; without it, RBCs, which are 500 to 1000 times more numerous than WBCs, would obscure the WBCs.
Visual WBC counting has been largely replaced by automated blood cell analyzers, but it is accurate and useful in situations in which no automation is available.
Medical laboratory professionals who analyze body fluids such as______ or _____ may employ visual WBC counting
cerebrospinal fluid or pleural fluid
A decreased WBC count is called______, and an increased WBC count is called______, but the WBC count alone has modest clinical value.
leukopenia
leukocytosis
Types of WBCs
NEB BLM
(A) neutrophil (segmented neutrophil, NEUT, SEG, polymorphonuclear neutrophil, PMN)
(B) band (band neutrophil, BAND)
(C) eosinophil (EO)
(D) basophil (BASO)
(E) lymphocyte (LYMPH)
(F) monocyte (MONO)
are phagocytic cells whose major purpose is to engulf and destroy microorganisms and foreign material, either directly or after they have been labeled for destruction by the immune system.
Neutrophils
The term_____ refers to their multilobed nuclei.
segmented
The cytoplasm of _______ contains pink- or lavender-staining granules filled with bactericidal substances.
Neutrophils
An increase in neutrophils is called_____ and often signals bacterial infection.
neutrophilia
A decrease in neutrophils is called______ and has many causes, but it is often caused by certain medications or viral infections.
neutropenia
____are slightly less mature neutrophils with a nonsegmented nucleus in a____ or ____ shape
Bands
U or S
An increase in bands also signals bacterial infection and is customarily called a_______
left shift
are cells with round, bright orange-red cytoplasmic granules filled with proteins involved in immune system regulation.
Eosinophils
Eosinophils are cells with ________ cytoplasmic granules filled with proteins involved in immune system regulation.
round, bright orange-red
________ often signals a response to allergy or parasitic infection.
eosinophilia —increased eosinophil
are cells with dark purple, irregular cytoplasmic granules that obscure the nucleus.
Basophils
Basophils are cells with ______cytoplasmic granules that obscure the nucleus.
dark purple, irregular
The basophil granules contain_____ and various other proteins.
histamines
is rare and often signals a hematologic disease.
elevated basophil count —Basophilia
The distribution of basophils and eosinophils in blood is so small compared with that of neutrophils that the terms _____ and _____are theoretical and not used.
eosinopenia and basopenia
Neutrophils, bands, eosinophils, and basophils are collectively called_____ because of their prominent cytoplasmic granules, although their functions differ.
granulocytes
Granulocytes
Neutrophils, bands, eosinophils, and basophils
comprise a complex system of cells that provide for host immu-nity.
Lymphocytes
recognize foreign antigens and mount humoral (antibodies) and cell-mediated antagonistic re-sponses.
Lymphocytes
On a Wright-stained blood film, most_____ are nearly round, are slightly larger than RBCs, and have round featureless nuclei and a thin rim of nongranular cy-toplasm.
lymphocytes
An increase in the lymphocyte count is called______ and often is associated with_______
Lymphocytosis
viral infections
An abnormally low lymphocyte count is called_______ and is often associated with______ or ______
lymphopenia or lymphocytopenia
drug therapy or immunodeficiency
The______ is an immature macrophage passing through the blood from its point of origin, usually the bone marrow, to a targeted tissue loca-tion.
monocyte
are the most abundant cell type in the body although it comprise a minor component of peripheral blood WBCs.
Macrophages
_____occupy every body cavity; some are motile and some are immobilized.
Their tasks are to identify and phagocytize (engulf and consume) foreign particles and assist the lymphocytes in mounting an immune response through the assembly and presentation of_______.
Macrophages
antigen epitopes
On a Wright-stained blood film,______ have a slightly larger diameter than other WBCs, blue-gray cytoplasm with fine azure granules, and a nucleus that is usually indented or folded.
monocytes
On a Wright-stained blood film, monocytes have a slightly larger diameter than other WBCs, _____cytoplasm with _____granules, and a nucleus that is usually_____
blue-gray
fine azure
indented or folded
An increase in the number of monocytes is called______. It may be found in certain______
Medical laboratory professionals seldom document a decreased monocyte count, so the theoretical term____ is seldom used.
monocytosis —infections or in inflammation.
monocytopenia
is an uncontrolled proliferation of a clone of malignant WBCs.
Leukemia
Leukemias may involve any of the cell lines and are categorized by their respective _____ and _____
immunophenotypes and genetic aberrations
Some leukemias are more common in a specific age group;
______is more prevalent in people older than 65 years, whereas
______is the most common form of childhood leukemia
chronic lymphocytic leukemia
acute lymphoblastic leukemia
Medical laboratory scientists participate in characterization of leukemias using
Wright-stained bone marrow smears
flow cytometric immunophenotyping
molecular diagnostic technology
cytogenetics
cytochemical staining
, are true blood cells that maintain blood vessel integrity by initiating vessel wall repairs
Platelets, or thrombocytes
_____rapidly adhere to the surfaces of damaged blood ves-sels, form aggregates with neighboring platelets to plug the vessels, and secrete proteins and small molecules that trigger_____, or clot formation.
Platelets
thrombosis
Platelets are the major cells that control______, a series of cellular and plasma-based mechanisms that seal wounds, repair vessel walls, and maintain vascular patency (unimpeded blood flow)
hemostasis
Platelets are only______ in diameter, round or oval, anucleate (for this reason some hematologists prefer to call platelets “_______”), and slightly granular
2 to 4 um
cell fragments
Their small size makes them appear insignificant, but they are essential to life and are extensively studied for their complex physiology.
Platelets
Uncontrolled______ and hemostatic activation is responsible for deep vein thrombosis, pulmonary emboli, acute myocardial infarctions (heart attacks), cerebrovascular accidents (strokes), peripheral artery disease, and repeated spontaneous abortions (miscarriages)
platelet
The microscopist counts platelets using the same technique used in counting WBCs on a______, although a different counting area, diluent, and dilution is usually used
hemacytometer
Owing to their small volume, platelets are hard to distinguish visually in a hemacytometer, and_____ provides for easier identification.
Automated blood cell analyzers have largely replaced visual platelet counting and provide greater accuracy
phase microscopy
One advantage of automated blood cell analyzers is their ability to generate a______, which is unavailable through visual methods.
The presence of predominantly larger platelets generates an elevated ____ value, which sometimes signals a regenerative bone marrow response to platelet consumption
mean platelet volume (MPV)
Elevated platelet counts, called_____, signal inflammation or trauma but convey modest intrinsic significance.
thrombocytosis
is a rare malignant condition characterized by extremely high platelet counts and uncontrolled platelet production.
It is a life-threatening hematologic disorder
Essential thrombocythemia
A low platelet count, called______, is a common consequence of drug treatment and may be life threatening.
Because the platelet is responsible for normal blood vessel maintenance and repair, ______ is usually accompanied by easy bruising and uncontrolled hemorrhage
thrombocytopenia
accounts for many hemor-rhage-related emergency department visits.
Accurate platelet counting contributes to patient safety because it provides for the diagnosis of ______ in many disorders or therapeutic regimens.
Thrombocytopenia
