Lab 42 blood Testing Flashcards
Why are tests performed on blood?
To help identify various diseases/conditions, tests are often performed on blood to determine how its composition compares with normal values.
What do the tests performed on blood commonly include?
Commonly includes measuring hemacrit, hemoglobin, coagulation, and cholesterol.
What is hemacrit?
Red blood cell percentage.
What happens when a blood sample is collected in a capillary tube?
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.
What does spinning a capillary tube in a centrifuge do?
Accelerate the process
What is the red layer at the bottom of the tube?
The red layer at the bottom portion of the tube represents the compacted red blood cells
What is the percentage of the compacted red blood cells called?
The percentage of compacted red blood cells is called the hemacrit
What percentage of a sample is red blood cells?
About 45% of the volume.
What is the thin white layer that forms atop the composed red blood cells?
A thin whitish layer known as the “Buffy coat” forms on top of the compacted RBC layer.
What does the Buffy coat contain?
The Buffy coat contains the white blood cells and platelets.
What percentage of a sample is white blood cells or Buffy coat
Normally less then one percent of the total volume.
What is the plasma?
The remaining straw colored upper portion of the contents contains the plasma. The plasma makes up about fifty five percent of the total volume.
How much of the RBC does hemoglobin compose?
Molecules of the protein Hemoglobin (Hb) compose about 1/3 of the volume within the red blood cell.
What happens when you take a breath?
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.
What is the hemoglobin molecule composed of?
The hemoglobin molecule is composed of four protein units (two alpha, two beta)
What does each hemoglobin molecule contain?
Each containing a heme molecule with an atom of iron. The iron binds to one oxygen molecule
How many oxygen molecules can bind to a hemoglobin molecule
Four
What happens when oxygen binds to hemoglobin?
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.
What happens when oxygen detaches (dissociates) from hemoglobin?
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.
What is percent saturation of hemoglobin?
The amount of oxygen bound to hemoglobin molecules is expressed as the percent saturation of hemoglobin.
What is the percent saturation of hemoglobin dependent on?
- The most important variable being the partial pressure of oxygen (similar to concentration of oxygen in the air)
- temperature
- pH
- Carbon dioxide levels
What is an oxygen dissociation curve?
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)
What does a shift right indicate?
A shift right indicates that for any given partial pressure of oxygen, there is a decrease in the percent saturation of hemoglobin.
What does a shift left indicate?
A shift left indicates that for any given partial pressure of oxygen, there is an increase in the percent saturation of hemoglobin.
