|
This experiment is courtesy of 
|
Time Allowance:
60 minutes
Primary Goals:
simulating blood coagulation
simulating blood separation
|
Blood Chemistry was developed by research scientist Paul Reibach, Ph.D.
and teacher Kate Loal from S.B. Huey School in the Philadelphia School
District to help students learn about the basic properties of blood,
and why blood type is important.
|
|
What You'll Need
|
Materials required for eight groups:
|
1 graduated cylinder
1 mixing jar
24 pipettes
safety glasses
Nitrile safety gloves
1 container of red glitter
1 bottle white vinegar
1 bottle of Future® acrylic floor polish
1 small bottle of red food coloring
1 bottle mineral oil
water
|
|
56 plastic vials
- 8 labeled Type A
- 8 labeled Type B
- 8 labeled Type O
- 8 labeled whole blood
- 8 labeled A+O
- 8 labeled B+O
- 8 labeled A+B
|
|
|
|
In Advance
|
What you must do before the class begins:
|
"Type A Blood" -- Measure 25 ml floor polish, 100 ml water and 1 ml red food dye in a mixing jar.
Fill the 8 small vials labeled "Type A" with this mixture, and put the caps on the vials.
Clean the mixing jar and graduated cylinder thoroughly.
"Type B Blood" -- Measure 25 ml vinegar, 100 ml water and 1 ml red food dye in a mixing jar.
Fill the 8 small vials labeled "Type B" with this mixture and put the caps on the vials.
Clean the mixing jar and graduated cylinder thoroughly.
"Type O Blood" -- Measure 125 ml water and 1 ml red food dye in mixing jar.
Fill the 8 small vials labeled "Type O" with this mixture and put the caps on the vials.
Clean the mixing jar and graduated cylinder thoroughly.
Fill the 8 small vials labeled "whole blood" with mineral oil. Add red glitter. Cap the vials.
|
|
|
|
Safety Tips
|
Explain to the class these tips for safety:
|
Safety glasses are recommended. Although the materials
being used in the experiment are generally safe, they can irritate or
sting eyes upon contact. If contact does occur, flush eyes copiously
with water.
Safety gloves should also be worn during this
experiment, since you will be simulating working with blood. It's
important for students to understand that all health professionals wear
gloves to prevent risks associated with contractible diseases like AIDS
and hepatitis.
Wash hands immediately after conducting the experiment.
Do not put hands or fingers in mouth, or rub eyes, until after hands
have been washed.
Liquid materials used during the experiment can stain
many surfaces, and should not be allowed to remain on clothing,
upholstery or wood.
Clean up any spilled materials immediately, as they can create a slip hazard on a tile or linoleum floor.
|
|
|
|
Blood Types
|
Before you begin, you should talk with the students about blood types.
In some ways, every person's
blood is the same. But, when analyzed under a microscope, distinct
differences are visible. In the early 20th century, an Austrian
scientist named Karl Landsteiner classified blood according to those
differences. He was awarded the Nobel Prize for his achievements.
Landsteiner observed two
distinct chemical molecules present on the surface of the red blood
cells. He labeled one molecule "A" and the other molecule "B." If the
red blood cell had only "A" molecules on it, that blood was called type
A. If the red blood cell had only "B" molecules on it, that blood was
called type B. If the red blood cell had a mixture of both molecules,
that blood was called type AB. If the red blood cell had neither
molecule, that blood was called type O.
Why is blood type important?
There are times when a person
might need to receive a blood transfusion -- that is, receive another
person's blood to replenish their own. If someone is in a bad accident
where they've lost blood, or if someone is having surgery or is ill,
they may need blood to replace what they've lost and to keep the oxygen
supply to the body at a healthy level.
It's important that an
individual who receives a blood transfusion receive a blood type that
is compatible with their own, or it could cause serious,
life-threatening complications.
If two different blood types are
mixed together, the blood cells may begin to clump together in the
blood vessels, causing a potentially fatal situation. Therefore, it is
important that blood types be matched before blood transfusions take
place. In an emergency, type O blood can be given because it's most
likely to be accepted by all blood types. However, there is still a
risk involved.
- A person with type A blood can donate blood to a person with type A or type AB.
- A person with type B blood can donate blood to a person with type B or type AB.
- A person with type AB blood can donate blood to a person with type AB only.
- A person with type O blood can donate to anyone.
- A person with type A blood can receive blood from a person with type A or type O.
- A person with type B blood can receive blood from a person with type B or type O.
- A person with type AB blood can receive blood from anyone.
- A person with type O blood can receive blood from a person with type O only.
Because of these patterns, a
person with type O blood is said to be a universal donor. A person with
type AB blood is said to be a universal receiver. In general, however,
it is still best to mix blood of matching types.
|
|
|
|
Demonstration
|
Explain to the class that you're about to investigate what happens when different blood types are mixed.
Divide the class into 8 groups and arrange desks/chairs
so that each member of the group can participate and observe the
experiment.
Explain to the students that they are not working with
actual blood samples -- that you have used special solutions of water,
vinegar, floor polish and red food coloring to simulate real blood.
SAFETY CHECK!!! Make sure all the students are wearing safety glasses and their gloves.
|
What you will do to demonstrate simulating blood coagulation (Part I)
|
Distribute to each group:
- 1 vial of Type A "blood"
- 1 vial of Type B "blood"
- 1 vial of Type O "blood"
- 1 empty vial labeled "A+B"
- 1 empty vial labeled "A+O"
- 1 empty vial labeled "B+O"
- 1 vial of "Whole blood"
- 3 pipettes
- enough safety glasses and gloves for each student in the group
Instruct the students to:
Use one dropper for each of the blood types -- they MUST NOT mix the droppers.
Create a mixture in the vial marked "A+O".
- First, ask them to hypothesize what is going to happen when you mix types A and O blood.
- Carefully measure out a few dropperfuls of "Type A" blood and deposit it in the vial marked "A+O".
- Carefully measure out a few dropperfuls of "Type O" blood and deposit it in the same vial.
- Ask the students to report their observations aloud, record
them in their workbooks. (Note to instructor, the mixture will not
coagulate).
Create a mixture in the vial marked "B+O".
- Ask them to hypothesize what is going to happen when you mix types B and O blood.
- Carefully measure out a few dropperfuls of "Type B" blood and deposit it in the vial marked "B+O".
- Carefully measure out a few dropperfuls of "Type O" blood and deposit it in the same vial.
- Ask the students to report their observations aloud, record
them in their workbooks.(Note to instructor, the mixture will not
coagulate).
Create a mixture in the vial marked "A+B".
- Ask them to hypothesize what is going to happen when you mix types A and B blood.
- Carefully measure out a few dropperfuls of "Type A" blood and deposit it in the vial marked "A+B".
- Carefully measure out a few dropperfuls of "Type B" blood and deposit it in the same vial.
- Ask the students to report their observations aloud, record
them in their workbooks. (Note to instructor, the blood WILL
coagulate).
Discussion for Part One
- Which blood combinations are compatible? Not compatible? Why?
- What would have happened if the "A+B" solution had been real
blood, in a live human being? (Normal, healthy blood does not clump
like the A+B solution. This "clumping" can lead to blood clots or other
masses, which can block blood vessels and prevent the proper flow of
blood and oxygen.)
- Why don't the "A+O" and "B+O" combinations "coagulate." (Type
O blood is the universal donor, and is compatible with or "matches" all
blood types.)
- If these solutions were real blood samples, what extra
precautions would we need to take in conducting the experiment?
(Medical professionals including doctors, nurses and others wear masks
when handling blood.)
- Why? (Explain that blood can carry diseases that are
infectious -- such as AIDS, HIV and hepatitis. If diseased blood comes
in contact with our own, we can become infected, too.)
|
What you will do to demonstrate simulating blood separation (Part II)
|
Blood may be transfused as whole
blood or as one of its components. Because patients seldom require all
of the components of whole blood, it makes sense to transfuse only that
portion needed by the patient for a specific condition or disease.
Whole blood is a living tissue
that circulates through the heart, arteries, veins and capillaries
carrying nourishment, electrolytes, hormones, vitamins, antibodies,
heat and oxygen to the body's tissues. Whole blood contains red blood
cells, white blood cells and platelets suspended in a fluid called
plasma.
If blood is treated to prevent
clotting and permitted to stand in a container, the red blood cells,
weighing the most, will settle to the bottom; the plasma will stay on
top; and the white blood cells and platelets will remain suspended
between the plasma and the red blood cells. A centrifuge may be used to
hasten this separation process.
Red blood cells contain
hemoglobin, a complex iron-containing protein that carries oxygen
throughout the body and gives blood its red color. Patients who benefit
most from transfusions of red blood cells include those with chronic
anemia resulting from kidney failure, malignancies, or gastrointestinal
bleeding and those with acute blood loss resulting from trauma.
Plasma is the liquid portion of
the blood -- a protein-salt solution in which red and white blood cells
and platelets are suspended. It serves a variety of functions, from
maintaining a satisfactory blood pressure and volume to supplying
critical proteins for blood clotting and immunity. It also serves as
the medium of exchange for vital minerals such as sodium and potassium,
thus helping maintain a proper balance in the body, which is critical
to cell function. Plasma is obtained by separating the liquid portion
of blood from the cells.
Cryoprecipitated AHF is the
portion of plasma that is rich in certain clotting factors. It is used
to prevent or control bleeding.
Platelets (or thrombocytes) are
very small cellular components of blood that help the clotting process
by sticking to the lining of blood vessels. Platelets are made in the
bone marrow and survive in the circulatory system for an average of
9-10 days before being removed from the body by the spleen. The
platelet is vital to life, because it helps prevent both massive blood
loss resulting from trauma and blood vessel leakage that would
otherwise occur in the course of normal, day-to-day activity. Units of
platelets are prepared by using a centrifuge to separate the
platelet-rich plasma from the donated unit of whole blood. The
platelet-rich plasma is then centrifuged again to concentrate the
platelets further.
Instruct the students to:
- Pick up the jar marked "whole blood" and shake it vigorously.
- Set the jar on a table, do not move it or pass it around.
- Explain that while the glitter is suspended in the mineral oil, it represents whole blood.
- As the glitter settles, explain that the solution represents
separated blood -- the glitter representing "red blood cells" and the
mineral oil representing plasma.
Discussion for Part Two
- What is a "centrifuge"?
A centrifuge is a powerful laboratory device that spins rapidly to
magnify the force of gravity. It is used to separate blood samples into
blood cells and plasma.
The centrifuge simulates an extreme force of gravity, which forces the blood to separate.
Doctors and other medical professionals use the separated blood for a variety of medical procedures.
- How do we preserve red blood cells and blood plasma?
(Whole and separated blood samples are preserved with special refrigeration and storage units.)
- Today, many individuals are not allowed to donate blood. Why?
(If an individual has an infectious disease, such as AIDS/ HIV
or hepatitis, it can be fatal if it's administered to another
individual through a transfusion. Individuals who have
hyper/hypotension or an abnormal heart rate may also be denied
permission to donate blood. Certain religious sects do not allow blood
donation or transfusions. Hemopheliacs lack an important clotting agent
in their blood, which could make blood donation fatal for them.)
|
|
|
|
|