CV Lab Flashcards
Blood pressure can be influenced primarily by:
cardiac output, peripheral resistance, and blood volume. Body position, exercise, and other factors may affect some of these variables.
Systolic pressure is
the maximum pressure in an artery during ventricular contraction.
Diastolic pressure is the
minimum pressure in an artery during ventricular relaxation.
Blood pressure is manually determined using a
sphygmomanometer (blood pressure cuff) along with a stethoscope.
The sphygmomanometer is placed around an artery (typically the
brachial artery of the arm), and the stethoscope is placed distal to the cuff.
The cuff is oriented such that the
tubing is facing anterior and exits the cuff distally.
Inflation of the cuff blocks blood flow
distally in the artery.
Slow deflation of the cuff allows blood to
slowly flood back into the artery. The practitioner can determine systolic and diastolic pressure by listening to the blood pressure (Korotkoff) sounds(see image below).
Korotkoff sounds are heard from an artery as
pressure is applied by a sphygmomanometer below systolic pressure.
Blood pressure is recorded using two numbers, one on top of the other. The top number is the
systolic pressure, and the bottom number is the diastolic pressure.
Normal adult blood pressure for those between the ages of 20-40 is
115/70. Blood pressure is lower as an adolescent, and higher as we age.
Chronically elevated blood pressure over 130/80 is called
hypertension.
Chronically low blood pressure less than 90/60 is called
hypotension.
Cardiac muscle cells contract in response to a rapid series of
electrical potential changes that travel through the heart along the conduction system.
Under normal conditions, electrical activity of the heart is spontaneously generated by the
sinoatrial (SA) node, the heart’s physiological pacemaker.
This electrical impulse is propagated throughout the
right and left atria, stimulating the myocardium of the atria to contract.
The electrical activity propagates throughout the atria from the
SA node to the atrioventricular (AV) node.
The AV node functions as a
critical delay in the conduction system.
This prevents the atria and ventricles from contracting at
the same time, and provides time for blood to flow from the atria to the ventricles.
The distal portion of the AV node is known as the
AV bundle (bundle of His), which splits into right and left bundle branches in the interventricular septum.
Both bundle branches taper out into the
subendocardiac conducting network (Purkinje fibers) that stimulate individual groups of ventricular myocardial cells to contract.
As the electrical current passes through the heart,
the cardiac muscle tissue is electrically excited, causing it to contract.
After contracting, the muscle cells relax again until the
next electrical current passes through, and the cycle is repeated.
An electrocardiogram (ECG) is an interpretation of the
electrical activity (depolarization and repolarization) of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body.
Einthoven’s triangle is formed by the use of the
left arm (LA), right arm (RA), and left leg (LL) electrodes to form the three pairs LA + RA, LA + LL, and RA + LL.
The output from each pair is known as
a lead.
The ECG recorder detects and amplifies the
tiny electrical changes on the skin from each pair caused when the heart muscle depolarizes during each heartbeat and compiles them as a recording that we call an electrocardiogram (ECG).
During each heartbeat, a healthy heart will have an orderly progression of a wave of depolarization triggered by the of the ventricles (T wave).
SA node (P wave) across the atria, passing through the AV node, and then spreading all over the ventricles (QRS complex) followed by repolarization
The ECG is made up of a s
traight baseline and waves. The waves can either move over or under the baseline. See an example in figure 1.
A segment is the area
between two waves. See an example in figure 2.
An interval is a
straight line and one or more waves. See an example in figure 3.
A complex is more than
one wave appearing in succession of one another. See the “QRS complex” in figure 4.
Brachial artery
Palpated within the front of the elbow (antecubital region)
+Common carotid artery
Palpated within the side of the neck (cervical region)
+Dorsalis pedis artery
Palpated on the top of the foot (dorsum of foot)
+Femoral artery
Palpated within the groin (inguinal region)
+Popliteal artery
Palpated within the back of the knee (popliteal region)
+Posterior tibial artery
Palpated between the medial side of ankle and Achilles tendon (between medial malleolus and calcaneal tendon)
+Radial artery
Palpated on the thumb side of the wrist
Leukocytes, or white blood cells (WBCs), can be divided into two subgroups depending on
whether or not their cytoplasm contains granules that are visible using a brightfield microscope.
Agranulocytesdo
not have visible granules.
+Lymphocytes
Small cells with a round nucleus taking up most of the volume of the cell.
+Monocytes
Large cells with a bean-shaped nucleus taking up half to nearly all the volume of the cell.
Granulocytescontain
granules that stain characteristic colors.
+Basophils
Contain dark purple or black granules. The nucleus is usually bilobed (two lobes).
+Eosinophils
Contain bright red granules. The nucleus is usually bilobed (two lobes).
+Neutrophils
Contain light pink and/or purple granules. The nucleus is multilobed (multiple lobes).
A differential white blood cell count (DIFF) determines the
percentage of the various types of white blood cells (WBCs), also known as leukocytes, in a blood sample.
Normal DIFF counts are approximately as follows*:
Neutrophils 40-70%; Lymphocytes 20-40%; Monocytes 2-8%; Eosinophils 1-4%; Basophils 0-1%
- Reference ranges can vary by ranges quoted are only approximate.
age, sex, methods of testing, and other factors. There are no nationally established reference ranges for DIFF values; instead, each laboratory tests a population and establishes its own reference ranges. Therefore, the reference
Blood types are determined by
the antigens that are present on the surface of red blood cells (RBCs, also known as erythrocytes).
Red blood cell membranes contain
glycoproteins and glycolipids that determine your ABO blood type and proteins that determine your Rh (+/-) blood type.
ABO blood type is determined by the presence of
A, B, both (AB), or neither (O) of the A or B antigens.
Rh blood type is determined by the presence of
(+) or lack of (-) the D antigen.
The blood plasma may also contain antibodies, depending on the
ABO and Rh blood types.
If you have blood type A, you will have ____ antibodies.
anti-B
If you have blood type B, you will have ____ antibodies.
anti-A
If you have blood type O, you will have both _____ antibodies and ____ antibodies.
anti-A; anti-B
If you have blood type AB, you will NOT have any ____ nor ____ antibodies.
anti-A; anti-B
No one has anti-D (Rh) antibodies unless they
are Rh- AND have been previously exposed to Rh+ blood.
Blood can only be donated from a person with a specific ABO antigen to a person
without antibodies for that antigen. Otherwise, agglutination (clumping) will occur.
Type A cannot donate to Type B or Type O because
they both have anti-A antibodies.
Type B cannot donate to Type A or Type O because
they both have anti-B antibodies.
Type AB cannot donate to Type A because
they have anti-B antibodies or Type B because they have anti-A antibodies.
Type O can potentially donate to everyone because
their blood has no antigen to attack. However, Type O should first have its own anti-A and anti-B antibodies removed.
Rh+ blood should not be transfused to an Rh- person; however, Rh- blood can be donated
to an Rh+ person.
Antigen
Any substance that is capable of causing an immune reaction. These are usually proteins, glycoproteins, or glycolipids.
+Antibody
An immune system protein that is found in most body fluids, especially blood plasma. Antibodies bind to antigens to aid the immune response.
+Agglutination
The clumping of cell bound antigens, as occurs when antibodies attach to ABO and D (Rh) antigens.
+Agglutinogen
The substance being clumped in an agglutination reaction. Antigens in blood typing are agglutinogens.
+Agglutinin
The substance causing clumping in an agglutination process. Antibodies in blood typing are agglutinins.
+Positive
Does NOT mean “good.” In testing, positive means what you are testing for is present.
+Negative
Does NOT mean “bad.” In testing, negative means what you are testing for is absent.
+Serum/Sera
Fluid containing antibodies.
Hematocrit (HCT) is the percentage of
erythrocytes, or red blood cells (RBCs), in a whole blood sample.
Hematocrit (HCT) is determined by
separating the formed elements from the plasma and measuring the packed red blood cell volume.
Normal hematocrit varies depending on many factors, but generally accepted ranges are:
Adult males: 42–52%; Adult females: 37–47%
An abnormally elevated hematocrit can occur for several reasons, such as
being at a high altitude, having an elevated testosterone level, with certain diseases, and if the person is “blood doping.”
Blood doping refers to any of several methods used to
increase the blood oxygen-carrying capacity.
Red blood cells (RBCs) are about
one-third hemoglobin.
Hemoglobin is the main protein that
carries oxygen and some carbon dioxide in the blood.
Healthy hemoglobin content in the blood varies with age, sex, and other factors. Generally, the values below are considered the normal range.
Male: 14–18g Hb/100 mL; Female: 12–16g Hb/100 mL
The hemoglobin content of blood is one measure of
the oxygen-carrying capacity of the blood.
An abnormally elevated hemoglobin content will occur if
someone is “blood doping.”
