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15: Blood

  • Page ID
    12535
  • Skills to Develop

    • Name the fluid component of blood and the three major types of formed elements, and identify their relative proportions in a blood sample

    Composition of Blood

    You have probably had blood drawn from a superficial vein in your arm, which was then sent to a lab for analysis. Some of the most common blood tests—for instance, those measuring lipid or glucose levels in plasma—determine which substances are present within blood and in what quantities. Other blood tests check for the composition of the blood itself, including the quantities and types of formed elements.

    One such test, called a hematocrit, measures the percentage of RBCs, clinically known as erythrocytes, in a blood sample. It is performed by spinning the blood sample in a specialized centrifuge, a process that causes the heavier elements suspended within the blood sample to separate from the lightweight, liquid plasma (Figure 15.1). Because the heaviest elements in blood are the erythrocytes, these settle at the very bottom of the hematocrit tube. Located above the erythrocytes is a pale, thin layer composed of the remaining formed elements of blood. These are the WBCs, clinically known as leukocytes, and the platelets, cell fragments also called thrombocytes. This layer is referred to as the buffy coat because of its color; it normally constitutes less than 1 percent of a blood sample. Above the buffy coat is the blood plasma, normally a pale, straw- colored fluid, which constitutes the remainder of the sample.

    The volume of erythrocytes after centrifugation is also commonly referred to as packed cell volume (PCV). In normal blood, about 45 percent of a sample is erythrocytes. The hematocrit of any one sample can vary significantly, however, about 36–50 percent, according to gender and other factors. Normal hematocrit values for females range from 37 to 47, with a mean value of 41; for males, hematocrit ranges from 42 to 52, with a mean of 47. The percentage of other formed elements, the WBCs and platelets, is extremely small so it is not normally considered with the hematocrit. So the mean plasma percentage is the percent of blood that is not erythrocytes: for females, it is approximately 59 (or 100 minus 41), and for males, it is approximately 53 (or 100 minus 47).

    image

    Figure 15.1 Composition of Blood The cellular elements of blood include a vast number of erythrocytes and comparatively fewer leukocytes and platelets. Plasma is the fluid in which the formed elements are suspended. A sample of blood spun in a centrifuge reveals that plasma is the lightest component. It floats at the top of the tube separated from the heaviest elements, the erythrocytes, by a buffy coat of leukocytes and platelets. Hematocrit is the percentage of the total sample that is comprised of erythrocytes. Depressed and elevated hematocrit levels are shown for comparison.

    image

    Figure 15.2 Summary of Formed Elements in Blood

    LAB 15 EXERCISES 15-1

    image

    image

    image

    image

    Plasma:

    1

    B

    A

    Identify the 3 major components of a hematocrit:

    Match the following items to their location: Albumin, Erythrocytes, Glucose, Chloride, Antibodies, Platelets, Monocytes, Neutrophils, Fibrinogen

    1.

    2.

    3.

    Normal range for men:

    Normal range for women:

    4

     

    5

     

    LAB 15 EXERCISES 15-2

    image

    1

    A

    Formed elements:

    2

    Identify the formed elements by their picture below:

    4

    Label the image below

    B

    1 5

    2

    6

    2

    3

    5

    7

    3

    4

    License: Anatomy & Physiology Lab Homework by Laird C. Sheldahl, under a Creative Commons Attribution-ShareAlike License 4.0

    LAB 14 EXERCISE 15-3

    1. Obtain a slide of blood from the slide box at your table.

    2. Follow the checklist above to set up your slide for viewing.

    3. View the slide on the objective which provides the best view (400X). Find the representative object.

    4. In the circle below the name, draw a representative sample of the blood cell, taking care to correctly and clearly draw their true shape in the slide. Draw your structures proportionately to their size in your microscope’s field of view.

    5. Repeat this for each of the blood cell types seen below.

      Erythrocytes

      Thrombocytes

      image

      License: Anatomy & Physiology Lab Homework by Laird C. Sheldahl, under a Creative Commons Attribution-ShareAlike License 4.0

      Leukocytes

      WBC:

      Leukocytes

      image

      image

      WBC:

      Leukocytes

      WBC:

      image

      License: Anatomy & Physiology Lab Homework by Laird C. Sheldahl, under a Creative Commons Attribution-ShareAlike License 4.0

      Leukocytes

      image

      image

      WBC:

      Leukocytes

      WBC:

      image

      ,

      LAB 15 EXERCISES 15-4

      Complete the following table using the following:

      A antigen

      Anti-A antibody

      .

      B antigen Anti-B antibody

      Rh antigen

      , Anti-Rh antibody

      Surface

      antigens

      O-

      O+

      A-

      A+

      Antibodies

      (in plasma)

      Surface antigens

      B-

      B+

      AB-

      AB+

      Antibodies (in plasma)

      LAB 15 EXERCISES 15-5

      FILL IN THE FOLLOWING TABLE

      Blood type

      Can safely receive:

      Can safely donate to:

      O+

         

      A-

         

      B+

         

      AB-

         

      AB+

         

      BLOOD: Histology, Models

      Hematocrit:

      • Plasma

      • Buffy coat

      • RBCs

         (including average ranges for men and women)

        Blood histology

      • Erythrocytes

      • Leukocytes:

         Granulocytes:

         Neutrophil

         Basophil

         Eosinophil

         Agranulocytes:

         Lymphocyte

         Monocyte

      • Platelets

      • Plasma

    Blood types students should understand the following terms and how they fit into the two blood typing mechanisms listed.

    know the antigens and antibodies present for a given blood type.

    Students must know which blood types can be safely donated to or received from another given blood type.

     Antigens

     Antibodies

     ABO system

    • Type A

    • Type B

    • Type AB

    • Type O

       Rh system

    • Rh+

    • Rh-