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STUDENT HANDOUT:
STUDENT HANDOUT:
LABORATORY REPORT FORM:
LABORATORY REPORT FORM:
INTRODUCTION:
INTRODUCTION:
The immune system prevents pathogens from causing disease once they enter the body. Our immune cells are found in our blood and are known as leukocytes. They are also known as white blood cells.
There are numerous types of white blood cells. Some cells target pathogens by phagocytosis. Others target pathogens through the release of chemicals (ex: histamine) that target destruction. The types of white blood cells and what they look like are shown below (Figure 1).
Figure 1. Leukocyte key. Image adapted from Wikimedia Commons.
These leukocytes are part of the innate immune response. The innate immune response is non-specific. This means that it will use similar mechanisms of attack, regardless of what type of pathogen it encounters.
There is another type of leukocyte known as a lymphocyte (Figure 2). These cells are part of the adaptive immune response. The adaptive immune response is pathogen-specific.
Figure 2. Leukocyte key. Image adapted from Wikimedia Commons.
Lymphocytes develop either in bone marrow (giving rise to B-cells) or the thymus gland (giving rise to T-cells). B-cells secrete a receptor that is known as an antibody (Figure 3). Antibodies recognize and bind to antigens. Antigens are defined as any substance that induces an immune response.
Figure 3. Schematic of an antibody. Image from Wikimedia Commons.
Once an antibody binds to a pathogen’s antigen, an immune response can result. Examples of immune responses can include:
Pathogens being “decorated” with antibodies, such that phagocytic leukocytes can recognize and destroy the pathogen.
Pathogens being “neutralized” with antibodies, such that receptors that permit pathogens from invading into certain cells are blocked.
Pathogens being “agglutinated.” Agglutination is when particles (pathogens) are clumped together.
Besides leukocytes, there are other components to blood. The components of blood include (Figure 4).
Leukocytes (White Blood Cells): Immune response
Erythrocytes (Red Blood Cells): Carry oxygen throughout the body.
Platelets: Involved in blood clotting.
Plasma: The liquid portion of blood. This includes water, salts and proteins (like antibodies).
Red blood cells can have surface antigens present on them. These antigens are known as “A” and “B.” It is these surface antigens that define an individual’s blood type (Figure 5). Individuals with both “A” and “B” on their red blood cells have type AB blood. Individuals that do not have either antigen on their red blood cells have type O blood.
Figure 5. ABO blood type. Image from Wikimedia Commons.
Within the liquid portion of blood, there may also be antibodies present. It is the presence of these antibodies that prevent individuals from receiving certain types of blood. As seen in Figure 5, an individual with type A blood has anti-B antibodies. This means if they receive any type B blood, their red blood cells will agglutinate, eventually causing the red blood cells to break down. Since type AB individuals do not produce any antibodies against A or B, they are universal acceptors of blood. Since type O individuals do not have A or B proteins and produce antibodies against A and B, they can only receive type O blood. Hence, type O individuals are universal donors.
We also classify blood as “+” or “-.” This is known as the Rhesus factor (Rh). Certain individuals (“+”) have this protein on the surface of their red blood cells. This protein was first found in Rhesus monkeys. Individuals that are positive receive either “+” or “-” blood. Individuals who are “-” can only receive “-” blood. It is from the antibodies and Rh factor that we get our blood compatibilities (donors and acceptors) (Figure 6).
Figure 6. Blood compatibilities. Image from Wikimedia Commons.
To determine the blood type of an individual, a simple test can be performed. A blood sample is mixed with anti-A, anti-B and anti-Rh serum (serum is the liquid portion of blood with clotting factors removed). If an agglutination reaction occurs, then the blood sample has that feature (Figure 7).
Figure 7. Bloodtyping results using anti-A, anti-B and anti-Rh serum.
OBJECTIVES:
OBJECTIVES:
Learn how to examine a blood smear and identify the components of blood.
Learn how to perform a blood typing experiment.
PRECAUTIONS:
PRECAUTIONS:
THE BLOOD YOUR TEACHER IS HAVING YOU WORK WITH IS FAKE BLOOD.
Use two hands to carry or move the microscope (Figure 8).
Figure 8. To properly carry the microscope, use one hand to hold the base of the microscope and the other to hold the arm.
EXPERIMENT #1: BLOOD OBSERVATIONS
EXPERIMENT #1: BLOOD OBSERVATIONS
MATERIALS (Work in pairs):
MATERIALS (Work in pairs):
Prepared Blood Smear
PROCEDURE:
PROCEDURE:
Make sure the microscope is set to the lowest objective. Place the slide onto the stage of the microscope. Turn on the microscope. Bring the objective lens and stage as close as possible with the coarse focus adjustment knob.
Look through the ocular lens and, using the coarse and fine adjustment knobs, bring the specimen into focus. There is very little detail at this magnification, but you will be able to tell that you are focused on the specimen.
Rotate the nosepiece to the next higher power lens and refocus using the fine adjustment knob only. Most microscopes are parfocal which then allow for only the use of the fine adjustment knob at higher magnification if properly focused at lower magnifications.
Continue to increase the magnification of the nosepiece objective and refocus with the fine adjustment knob.
OBSERVATIONS/CONCLUSIONS:
OBSERVATIONS/CONCLUSIONS:
On Figure 1 of the Laboratory Report Form, sketch your observations of the blood smear. Be sure to record the total magnification for each sketch by multiplying the ocular lens (10X) by the objective.
On your drawing, identify the red blood cell, leukocyte(s) and platelet(s).
QUESTIONS:
QUESTIONS:
What type of leukocyte(s) did you find on your blood smear? (Use Figure 1 to help you!)
Is/are these leukocytes you observed on the slide phagocytic or non-phagocytic?
Is/are these leukocytes you observed part of the innate or adaptive immune response?
What pathogen do these leukocytes mainly target?
EXPERIMENT #2: BLOOD TYPING
EXPERIMENT #2: BLOOD TYPING
MATERIALS (Work in pairs):
MATERIALS (Work in pairs):
Sample Blood Typing Kit. This kit should contain:
(a) Blood sample
(b) Anti-A, Anti-B and Anti-Rh (also known as Anti-D) sera.
(c) Toothpicks to mix
(d) Blood testing tray (any tray with 3 wells will work too).
PROCEDURE:
PROCEDURE:
Take a blood testing tray and place 3 to 4 drops of the unknown’s blood in each of the A, B and Rh wells.
Place 3 to 4 drops of Anti-A serum into the A well. Obtain a fresh toothpick and stir for 30 seconds. Wait several minutes and observe whether agglutination (clumping) occurs.
Place 3 to 4 drops of Anti-B serum into the B well. Obtain a fresh toothpick and stir for 30 seconds. Wait several minutes and observe whether agglutination (clumping) occurs.
Place 3 to 4 drops of Anti-Rh serum into the Rh well. Obtain a fresh toothpick and stir for 30 seconds. Wait several minutes and observe whether agglutination (clumping) occurs.
OBSERVATIONS/CONCLUSIONS:
OBSERVATIONS/CONCLUSIONS:
On Table 1 of the Laboratory Report Form, report your agglutination results.
What blood type did the unknown blood sample have?
QUESTIONS:
QUESTIONS:
What blood types can a person with the blood type you identified in this activity DONATE to?
What blood types can a person with the blood type you identified in this activity RECEIVE from?
KEY TERMS:
KEY TERMS:
adaptive immune response
agglutination
antibody
antigen
erythrocyte
innate immune response
leukocyte
pathogen
phagocytosis
FOR FUN...Blood Typing Game!
FOR FUN...Blood Typing Game!
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