1. INTRO TO HEMATOLOGY Flashcards
It is the science of blood or study of blood cells.
Hematology
greek word that means blood
haima
greek word that means study or science
logos
It deals with the study of normal and abnormal development, physiology, function and death or destruction or formed elements of blood.
Hematology
two main parts of blood
Liquid portion
Formed elements
Function of Blood (Rodak’s)
- transport O2 from lungs to tissues
- clears tissues of CO2
- transports glucose, proteins, lipids
- moves waste to liver and kidneys
average human or healthy individual amount of blood in the body
5L of blood
Formed Cells
RBC
WBC
Platelets
anucleate, biconcave, discoid cells filled with hemoglobin
transport O2 and CO2
Erythrocytes
color of the RBC
pink to red (salmon pink)
measurement of the diameter RBC
6-8 micrometer (7-8)
reason for the biconcave shape of RBC
central pallor (1/3 of the cell)
Why is RBC biconcave?
It cannot carry out O2-CO2 exchange function effectively if not biconcave
protect host from infection and injury/ inflammatory
Leukocytes
Types of WBCs:
Granulocytes
Agranulocytes
liquid portion of blood
plasma
they provide coagulation enzymes that protect vessels from trauma and maintain circulation and transport and nourish blood cells
plasma
Described “worms” in blood
Athanasius Kircher (1657)
Gave an account of RBCs
Anton van Leeuwenhoek (1674)
Described platelets as “petites plaques”
Giulio Bizzozero (1800s)
Developed the Wright stain
James Homer Wright (1902)
polychromatic, a mixture of acidic and basic dyes, remains the foundation of blood cell identification
Wright’s Romanowsky-type stain
the scientific term for cell appearance
morphology
cell morphology encompasses what parameters:
cell color, size, shape, cytoplasmic inclusions, nuclear condensation
what disorders can be detected by counting RBCs?
anemia or polycythemia
characterized by loss of O2-carrying capacity and is often reflected in a reduced RBC count or decreased Hgb concentration
Anemia
characterized by an increased circulating RBC mass which leads to hyperviscosity
Polycythemia
historically, microscopists counted RBCs by: (steps)
- pipette a tiny aliquot of blood
- mix with 0.85% normal saline
- diluted blood is transferred in a hemacytometer
- microscopist observe and count RBCs in selected area of the hemacytometer
- a mathematical formula is applies based on dilution and area on the hemacytometer counted
- the count is reported
why is normal saline used in the dilution of blood for RBC count
normal saline matches the osmolality of blood
dilution ratio used in counting RBCs
1:200
Pipette used in RBC count
thoma pipette
RBCs can be reported using these units:
per microliter (mm3), milliliter (cc), liter (L)
was developed before the 1900s and was the only way to count RBCs till 1958
visual RBC counting
First electronic counter patented in 1953
Coulter Counter
patented the coulter counter
Joseph and Wallace Coulter of Chicago, Illinois
it is the coulter principle that is used to count RBCs in many automated blood analyzers
direct current electrical impedance
a reddish protein found inside RBCs
hemoglobin
Hgb measurement relies on a weak solution of ___________ and _____________
potassium cyanide and potassium ferricyanide
a weak solution of potassium cyanide and potassium ferricyanide is also called:
Drabkin reagent
process of hemoglobin measurement: (steps)
- an aliquot of whole blood is mixed with a measured volume of Drabkin reagent
- Hemoglobin is converted to stable cyanmethemoglobin
- color intensity is measured using a spectrophotometer
- the color intensity is mathematically converted to hemoglobin concentration
Wavelength used in cyanmethemoglobin method?
540 nm
some blood cell analyzers replace cyanmethemoglobin with a formulation of the ionic surfactant (detergent) _________________________ to reduce environmental cyanide.
sodium lauryl sulfate
it is the ratio of the volume of packed RBCs to the volume of whole blood
hematocrit
other term for hematocrit
packed cell volume
process of hematocrit determination: (steps)
- Transfer blood to a plastic tube with uniform bore
- Centrifuge
- Measure the column of RBCs
- Divide the total length of the column of RBCs + plasma; the normal ratio approached 50%
uses the three results of RBC count, Hgb, and Hct to be computed
RBC Indices