David L. Umbarger, Montezuma-Cortez High School, Cortez, CO
BLOOD CIRCULATION LAB
Appropriate for grades 9-12.
OVERVIEW: This activity is designed to let students see blood
moving in the fin of a fish. They then can observe how the
hormone epinephrine (adrenaline) changes the flow of blood.
PURPOSE: A goldfish is wrapped in water soaked absorbent cotton
and placed in a large petri dish. A glass slide is placed under
and another over the caudal fin to hold the fin in place and help
restrict the fish from flipping the fin from position. When
positioned under a light microscope, the circulation of blood can
easily be observed, as well as the movement of blood from
arterioles to capillaries and to veinuoles. When epinephrine
(adrenaline) solution is added topically to the fin, the response
of the vessels can be observed.
OBJECTIVES: The student will be able to:
1. Compare and contrast the structure and function of arteriole,
capillary, and veinuole.
2. Relate the circulatory vessels found in a fish to the found
in humans.
3. Discuss how some hormones or drugs influence the distribution
of blood.
ACTIVITIES:
1. Give the following questions as a pre-lab activity:
a. What direction would you expect blood to flow through
the following structures in a fish fin: Arteriole?
Veinuole? Capillary?
b. What are the primary differences between the structures
listed above?
c. What effect would you expect epinephrine (adrenaline) to
have on the circulation of blood in the fin of a fish?
2. Completely saturate enough absorbent cotton with aquarium
water to completely surround a goldfish from the aquarium and
wrap it in the cotton and place it in a petri dish. Place a
glass slide under the caudal fin of the fish and then place
another over the fin. Make sure there is enough aquarium
water in the petri dish to keep the cotton very wet, yet not
so much to cover the bottom slide under the fish fin.
Position the fish fin on the microscope stage such that you
can observe the fin, near its distal portion, through the
microscope using the low power lens (you will probably need
to lower the light by adjusting the diaphragm to a smaller
setting.
Familiarize yourself with the flow of blood to the fin by
moving the petri dish around as you observe through the
microscope (Remember, the microscope inverts images.
Therefore, blood that appears to be flowing from the fin to
the body is actually flowing from the body to the fin.)
Locate an arteriole, veinuole, and capillary in the fish fin.
After finding each structure, turn to the medium powered lens
and observe. After each observation answer the questions
relative to the three structures:
a. What relative size is this
structure?
b. With what relative velocity does blood
move in this structure?
c. What direction does blood flow in this
structure? (toward head or tail)
d. Does blood move at a constant rate and in
one direction or in both directions and at
different rates?
3. How hormones effect circulation.
Locate a position on the fish fin under the microscope where
an arteriole and a capillary may both be observed at the same
time (use low power). While one person observes the blood
flow, an assistant should add two drops of epinephrine
solution to the fish fin just cranial to where the fin is
positioned under the microscope slide. The following
questions should then be answered after returning your fish
to a designated aquarium:
a. What observed reaction did the epinephrine have in the
rate of blood flow in the arteriole and capillary?
b. Under what conditions would you expect a fish to
naturally secrete epinephrine?
c. After observing the effect epinephrine has on the
circulation of blood in a fish fin (question a.), expand
on your answer in question b. to include an evolutionary
advantage the fish might obtain by secreting epinephrine
when under those conditions.
d. Based on your observations, under what conditions would
you secrete epinephrine, what effect would you expect it
to have, and what evolutionary advantages would you
expect it to provide?
RESOURCES/MATERIALS NEEDED: All described above.
TYING IT ALL TOGETHER: When administering the epinephrine, the
students will expect an increase in the fishes' blood flow based
on their knowledge of adrenaline being a cardio-vascular
stimulant. However, it restricts blood flow to the peripheral
circulatory network. Their observations serve as a good test for
their ability to separate what they bring in the lab as a
preconceived expectation from the actual observed effect. You
might follow this lab with a discussion of the need for a placebo
or other controls when doing labs of this nature.
Other drugs such as ethanol or nicotine may be used by some groups
and the results compared on the board after the lab.
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John Kurilecjmk@ofcn.org