LEC MODULE 4-5 UNIT 1 Flashcards
Compounds added to biological specimens to prevent them from clotting or to preserve the constituents of a specimen.
Additives
any substance that prevents blood from clotting
anticoagulant
A prenatal test to detect birth defects that is performed at an early stage of pregnancy and involves retrieval and examination of tissue from the chorionic villi. It is also called chorionic villus biopsy.
chorionic villus sampling
The sequential process by which the multiple coagulation factors of blood interact in the coagulation cascade, resulting in formation of an insoluble fibrin clot
coagulation or clotting
Variation that occurs in the amount of a substance during a 24-hour period
diurnal variation
Disruption of the red cell membrane causing release of hemoglobin and other components of red blood cells
hemolysis
One who practices phlebotomy, the individual drawing a specimen of blood.
phlebotomist
The puncture of a blood vessel to collect blood; literally, “the letting of blood in the treatment of disease.”
phlebotomy
Factors that affect specimens before tests are performed and that can lead to error if not controlled;
preanalytical errors
they are classified as controllable or uncontrollable
A substance or preparation added to a specimen to prevent changes in the constituents of a specimen.
preservatives
The non-cellular component of anticoagulated whole blood which contains clotting factors
plasma
The watery portion of blood that remains after coagulation has occurred and can be obtained after centrifugation.
serum
Any object which could readily puncture or cut the skin of an individual when encountered
sharps
A container designed for the disposal of sharps. This is being required and regulated by the Occupational Safety and Health Administration (OSHA)
sharps container
Collection of capillary blood usually from a pediatric patient by making a thin cut in the skin, usually at the heel of the foot.
skin puncture
A sample or portion of body fluid or tissue collected for examination, study, or analysis
specimen
All of the steps involved in obtaining an appropriate and identified blood specimen from an individual’s vein
venipuncture
Obstruction of the return of venous blood to the heart and distention of the veins; in phlebotomy, this is a temporary blockage caused by application of pressure, usually from a tourniquet.
venous occlusion
It is often used for skewed data
median
the most frequently observed value in a set of observations
mode
It is nnot commonly used as a measure of the data’s center but is more often used to describe data that seem to have two centers (bimodal).
mode
in the mode measurement of center/location, there cannot be more than one mode, if two or more values are equally common.
False. There can be more than one mode, if two or more values are equally common
It is possible that in a set of data there is no mode at all
True
Blood for analysis may be obtained from
veins, arteries, capillaries
what blood specimen is usually the specimen of choice
venous blood
what is the method used in obtaining venous blood
venipuncture
the act of obtaining blood sample from a vein using a needle
attached to a syringe or stoppered evacuated tube.
phlebotomy or venipuncture
locations where skin puncture can be done
- heel stick
- fleshy part of middle or fourth finger
- fleshy portion of earlobe
Analytic testing of blood involves the use of
- whole blood
- serum
- plasma
whole blood includes
both the liquid portion of the blood called
plasma and the cellular components
This requires blood
collection into a vessel containing an anticoagulant
whole blood
the clear yellow supernate on
top of the cells that fall toward the bottom after quite some time
plasma
If a tube does not contain an anticoagulant, the blood’s clotting
factors are active to form a clot incorporating the cells leaving the remaining yellowish liquid
to be called
serum
3 types of whole blood
- arterial blood
- venous blood
- capillary blood
are oxygenated and have uniform composition throughout the body
and is used for measuring blood gases and pH
arterial blood
blood gases are measured through determining the
partial pressure of O2 and CO2
In arterial blood collection, evacuated tubes are used instead of syringes because of the pressure in an arterial blood vessel.
False. In arterial blood collection, syringes are used instead of evacuated tubes because of the pressure in an arterial blood vessel.
primary arterial sites
- radial
- brachial
- femoral
Best specimen for evaluating
respiratory function
arterial blood
used for arterial blood gas analysis
arterial blood
Has high oxygen content and
consistency of composition
arterial blood
disadvantages of arterial blood collection
- difficult to obtain
- more painful and hazardous than venipuncture
- not normally used for routine blood tests
deoxygenated and have variable composition which can be
affected by metabolic activity and tissue it drains
venous blood
the specimen of choice for most
routine laboratory tests
venous blood
venous blood is usually obtained in the
antecubital area of the arm
it is where oxygen is lower
venous blood
-Good indicator of the physiological conditions throughout the body. -Easier to obtain than arterial blood sample -Used most frequently for testing
venous blood
disadvantages of venous blood collection
-May result to some minor and serious complications.
-Patients under serious conditions often lack readily accessible peripheral veins.
-Most patients physiologically can’t handle needles anywhere in their
body.
contain arterial blood, venous blood, and tissue fluid
capillary blood
capillary blood is obtained from
capillary beds
-which contains smallest veins (venules) and smallest arteries (arterioles)
It is often the specimen of choice for infants, very young
children, elderly patients with fragile veins, and severely burned patients
capillary blood
point-of-care testing is often performed using venous blood specimen.
False. capillary blood specimen
Capillary blood has lower glucose concentration and higher calcium, potassium, and total protein concentrations as compared to that of the venous blood.
False. Capillary blood has higher glucose concentration and lower calcium, potassium, and total protein concentrations as compared to that of the venous blood.
in using this blood specimen: -Only a very small amount of blood is needed -Collection is simple and relatively painless -Collection sites can be changed to minimize scarring and pain
capillary blood
disadvantages of capillary blood collection
-Not all tests can be run on capillary samples -Capillary blood collection can sometimes rupture the blood cells, leading to inaccurate results. -Calcified nodules may develop at the site of collection, especially in infants
what percentage of the blood is plasma
55%
what percentage of blood is water
92%
Plasma contains
7% proteins (albumin, gamma globulin, anti-hemophilic factor)
1% (mineral salts, sugars, fats, hormones, vitamins)
in obtaining plasma, blood is not allowed to clot
True
Plasma contains all clotting factors specifically
- Factor I
- Factor V
- Factor VIII
- Factor XIII
in gaussian distribution the mean, median, mode are
identical
a symmetrical curve representing the normal distribution
gaussian curve
the peak of the distribution should be centered on the
mean (best estimate of the true value)
the width of the curve is related to
standard deviation (a measure of data spread)
verification of a reference interval
transference
Inpatient samples should be
used for reference interval studies that
are designed to reflect a population
False
it indicates how the data are distributed or spread
measure of dispersion
This is often a good measure of dispersion for small samples of data
range
The range value of a data set is greatly influenced by the presence of just one unusually large or small value in the sample commonly referred to as
outlier
the most frequently used measure of
variation.
standard deviation
low standard deviation is good
true
defined as the ratio of the standard deviation to the mean value of the
data used in the analysis. It is expressed as a percentage.
coefficient of variation
measure of dispersion
- range
- standard deviation
- coefficient of variation
- variance
Average distance from the center of the data and every value in the data
set.
variance
3 commonly used descriptions of spread
- range
- standard deviation
- coefficient of variation
defined as closeness of agreement between the average value obtained from a large series of results of measurements and the true value
trueness
the closeness of agreement of mean value with the true value
true
difference between the average value and the true value
bias
this is expressed numerically and is inversely related to the trueness
bias
the closeness of agreement of a single measurement with the “true
value”
accuracy
accuracy is influenced by
bias and imprecision
combination of systematic error and random error
total error
inaccuracy and imprecision reflects
total error
refers to the
satisfaction of the needs and expectations of users and costumers.
quality
cost of conformance is divided into
prevention cost and appraisal cost
cost of nonconformance
internal and external failure cost
Degree to which a measured value of an entity agrees with its true value
accuracy
-Best measured through reference methods and peer group comparison
Degree to which measured values of an entity agree with each other
precision
-does not always connote accuracy
measured through determining standard deviation and coefficient of variance
precision
combination of accuracy and precision
reliability
Ability of the method to detect slight differences in concentration
sensitivity
The ability of a method to determine solely the compound it is supposed to measure
specificity
Describes the many fluctuations in a data that will interfere in the measurement of a substance in question
variance
defined as the liquid portion of blood that remains after
coagulation has occurred
serum
it is where clotting factors (factor I, V, VIII, XIII) are absent
serum
If the tube has
thrombin, the clotting time is approximately
5 minutes
For tubes with clot activator, ______ is necessary for clotting time and _______ for tubes without clot activator
30 mins; 60 mins
