Lab 42 blood Testing

Question 1

Why are tests performed on blood?

Answer 1

To help identify various diseases/conditions, tests are often performed on blood to determine how its composition compares with normal values.

Question 2

What do the tests performed on blood commonly include?

Answer 2

Commonly includes measuring hemacrit, hemoglobin, coagulation, and cholesterol.

Question 3

What is hemacrit?

Answer 3

Red blood cell percentage.

Question 4

What happens when a blood sample is collected in a capillary tube?

Answer 4

When a blood sample is collected in a heparinized (to prevent coagulation) capillary tube and is left standing the heavier cellular components settle to the bottom of the tube.

Question 5

What does spinning a capillary tube in a centrifuge do?

Answer 5

Accelerate the process

Question 6

What is the red layer at the bottom of the tube?

Answer 6

The red layer at the bottom portion of the tube represents the compacted red blood cells

Question 7

What is the percentage of the compacted red blood cells called?

Answer 7

The percentage of compacted red blood cells is called the hemacrit

Question 8

What percentage of a sample is red blood cells?

Answer 8

About 45% of the volume.

Question 9

What is the thin white layer that forms atop the composed red blood cells?

Answer 9

A thin whitish layer known as the “Buffy coat” forms on top of the compacted RBC layer.

Question 10

What does the Buffy coat contain?

Answer 10

The Buffy coat contains the white blood cells and platelets.

Question 11

What percentage of a sample is white blood cells or Buffy coat

Answer 11

Normally less then one percent of the total volume.

Question 12

What is the plasma?

Answer 12

The remaining straw colored upper portion of the contents contains the plasma. The plasma makes up about fifty five percent of the total volume.

Question 13

How much of the RBC does hemoglobin compose?

Answer 13

Molecules of the protein Hemoglobin (Hb) compose about 1/3 of the volume within the red blood cell.

Question 14

What happens when you take a breath?

Answer 14

When you take a breath of air into your lungs, the inspired oxygen diffuses across the respiratory membrane of the alveoli and capillary beds of your lungs into your blood, where it enters a RBC and binds to a hemoglobin molecule.

Question 15

What is the hemoglobin molecule composed of?

Answer 15

The hemoglobin molecule is composed of four protein units (two alpha, two beta)

Question 16

What does each hemoglobin molecule contain?

Answer 16

Each containing a heme molecule with an atom of iron. The iron binds to one oxygen molecule

Question 17

How many oxygen molecules can bind to a hemoglobin molecule

Answer 17

Four

Question 18

What happens when oxygen binds to hemoglobin?

Answer 18

It forms a bright red oxyhemoglobin and it is transported to systemic capillaries where it is released from the hemoglobin to diffuse into your body tissues.

Question 19

What happens when oxygen detaches (dissociates) from hemoglobin?

Answer 19

When oxygen detaches (dissociates) from the hemoglobin in the capillaries of the tissues it becomes a darker red and is called deoxyhemoglobin which can appear bluish when viewed through the skins blood vessel walls.

Question 20

What is percent saturation of hemoglobin?

Answer 20

The amount of oxygen bound to hemoglobin molecules is expressed as the percent saturation of hemoglobin.

Question 21

What is the percent saturation of hemoglobin dependent on?

Answer 21

• The most important variable being the partial pressure of oxygen (similar to concentration of oxygen in the air)
• temperature
• pH
• Carbon dioxide levels

Question 22

What is an oxygen dissociation curve?

Answer 22

The relationship of percent saturation to partial pressure of oxygen can be graphed to produce an oxygen dissociation curve.
(The term dissociate means to separate thus oxygen separates from hemoglobin)

Question 23

What does a shift right indicate?

Answer 23

A shift right indicates that for any given partial pressure of oxygen, there is a decrease in the percent saturation of hemoglobin.

Question 24

What does a shift left indicate?

Answer 24

A shift left indicates that for any given partial pressure of oxygen, there is an increase in the percent saturation of hemoglobin.

Question 25

What does a CBC measure?

Answer 25

A CBC measures WBC count, RBC count, (including average red blood cell size) hemacrit, and hemoglobin concentration (including hb amount per RBC)

Question 26

What is a CBC used for?

Answer 26

A CBC is used to detect or monitor various health conditions.

Question 27

What is an increased hemacrit a result of?

Answer 27

An increased hemocrit may be a result of dehydration, living at higher altitudes, smoking, emphysema, or the abuse of EPO (erythropoietin) by athletes for blood doping purposes.

Question 28

What are decreased levels of hemocrit attributed to?

Answer 28

Decreased values of hemocrit or hemoglobin levels could be attributed to anemia, hemmorage, dietary deficiencies, kidney disease where EPO production is impaired, infections, hereditary, bone marrow cancer or exposure to ionizing radiation.

Question 29

What is anemia?

Answer 29

Anemia is a condition that has many causes but the consequences (low oxygen levels, low blood osmolarity, and low blood viscosity) put more stress on the cardiovascular system and may result in cardiac failure

Question 30

What is hemostasis?

Answer 30

Stoppage of bleeding, called hemostasis involves 3 defense mechanisms: blood vessel spasm, platelet plug formation and coagulation.

Question 31

What is coagulation?

Answer 31

The coagulation mechanism involves a series of chain reactions that result in a blood clot.

Question 32

What is the final stage of blood clot formation?

Answer 32

The final stage of blood clot formation occurs when thrombin converts a soluble plasma protein into insoluble threads of fibrin.

Question 33

What does the fibrin do?

Answer 33

The fibrin mesh traps cellular components of the blood, stopping the blood loss.

Question 34

How long does it take the fibrin to form?

Answer 34

Once blood clotting is initiated it usually takes 3-8 minutes for fibrin to form.

Question 35

What can clotting deficiencies be related to.

Answer 35

Clotting defiencies could be attributed to low platelet count, leukemia, hemophilia, liver disease, malnutrition, exposure to ionizing radiation or anticoagulating drugs.