Blood Laboratory

For this laboratory, you have several blood samples provided.

Your job is to use standard blood tests to discover whether these blood samples are normal or not, and, if they are abnormal, to discover what is abnormal about them. Take a sample of blood from one of the test tubes. Each lab group should test all the samples provided.

Blood Staining

Before lab: do the online virtual blood staining lab at http://www.getbodysmart.com/ap/circulatorysystem/blood/wbcs/wbcdifferential/tutorial.html . This way, you’ll know what you’re doing and what you are looking for through the microscope.

The chemicals used in staining blood are toxic. Be careful with them! They will also stain your clothes, if you spill them.

To begin, make a blood smear on a slide. Do this by putting a drop of blood on the slide near one end, and using the edge of another slide to spread it across the slide. Do one slide of each blood sample. Again, be sure to keep them labeled! You may find it easier to make a smear if you dilute the blood sample with some normal saline.

Why would we use saline instead of water for diluting the blood?

Stain your slide according to the directions at the staining station.

Now, examine your slide under oil immersion. You should be able to notice the following:

Erythrocytes - small, biconcave, pink.

Check for any abnormalities in the shape of the erythrocytes. Are they swollen or shrivelled? This will tell you whether the plasma is hypertonic or hypotonic. Lumps on their surfaces are called blebs.

Erythrocytes can be too big (macrocytic -- usually seen in folic acid or Vitamin B12 deficiency anemias), normal sized (normocytic) or too small (microcytic - usually seen in iron-deficiency anemia). They can be too pale (hypochromic) or normally colored (normochromic). They should not have nuclei; if they do, they are immature and have been released from the bone marrow to deal with an emergency. That would indicate severe anemia.

Platelets - dark violet-purple, small; often found tangled in fibrin, in clots.

Neutrophils - purple, misshapen nucleus; may look like a chain of beads. Contain lilac-pink granules in cytoplasm.

Eosinophils - purple nucleus, but reddish-orange granules

Basophils - purple nucleus, violet granules

Monocytes and Lymphocytes - have dark purple nuclei and almost no cytoplasm.

You should be able to identify these cells by sight. An increase in the white blood cell number indicates infection.

Hematocrit

The hematocrit is the percent of the blood that is made up of cells. If the blood were 40% cells and 60% plasma, the hematocrit would be 40. To determine this, you place a blood sample in a capillary tube and centrifuge the tube until the cells collect at the bottom. You can then measure the height of the cell column and the height of the total blood column, and determine hematocrit by dividing the height of the cell column by the height of the total blood column.

First, make sure you have the necessary equipment. You need capillary tubes, cryoseal sealant, and a hematocrit centrifuge. Fill the capillary tubes about 3/4 of the way with blood. The blood should flow up the tube relatively easily. After filling the tube, plug it by pushing it into the cryoseal pad. Fill two tubes from your sample of blood. Be sure not to mix them up!

Now, place the capillary tubes in the centrifuge. You'll see that inside the centrifuge are numbered slots in which the tubes can lie, with a scale next to them. ALWAYS PLACE THE TUBES WITH THE CRYOSEAL PLUG TOWARDS THE OUTER EDGE OF THE CENTRIFUGE! Otherwise, all the blood will leak out the tube and splatter the centrifuge.

Record the numbers of the slot you put your tubes in.

When the centrifuge is full, screw on the lid and press the button to start it. Let the centrifuge finish and completely stop before you open the lid. Then you can remove your tubes and measure the blood and plasma columns with a ruler, or you can read their heights off the scale in the centrifuge. If you do that, though, be sure the top of the cryoseal plug is at the zero mark.

Read the heights of the cell column and the total blood column and calculate the hematocrits of the blood samples.

Normal hematocrit values are 37-47% for females and 42-54% for males. If the hematocrit is too low, the person has anemia (a=lacking; -emia=blood). If it is too high, they have polycythemia (poly = many; cyt=cells; -emia=blood).

Blood glucose

Test the blood glucose according to the instructions on the glucometers. Normal blood glucose shoud be between 70-110 mg/dL. An elevated glucose is hyperglycemia; a decreased glucose is hypoglycemia.

Turn in a copy of the record sheet below for each blood sample.