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Title Toxicology of Alcohol

(estimated time: 2 hours) Table of Contents

I. Pre-requisite knowledge 2

II. Massachusetts Science and 2

Technology/Engineering Frameworks Compliance

III. Content to be Taught 2

IV. Rationale 3

V. Goals 3

VI. Objectives 3

VII. Background for Teacher 3

VIII. Engagement 4

IX. Exploration: Lab Protocol 4-7

X. Explanation 7

XI. Evaluation 7 XII. Appendix 8

XIII. Toxicology Lab Prep 9-10

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How much is too much? Daphnia/Toxicology lab

I. Pre-requisite knowledge

Students should be familiar with the use of microscopes and the basics of graphing.

II. Massachusetts Science and Technology/Engineering Frameworks Compliance

SIS1. Make observations, raise questions, and formulate hypotheses. Observe the world from a scientific perspective. Pose questions and form hypotheses based on personal observations, scientific articles, experiments, and knowledge. SIS2. Design and conduct scientific investigations. Articulate and explain the major concepts being investigated and the purpose of an investigation. Select required materials, equipment, and conditions for conducting an experiment. Identify independent and dependent variables. Write procedures that are clear and replicable. Employ appropriate methods for accurately and consistently -making observations -making and recording measurements at appropriate levels of precision -collecting data or evidence in an organized way SIS3. Analyze and interpret results of scientific investigations. Present relationships between and among variables in appropriate forms. Represent data and relationships between and among variables in charts and graphs. Use appropriate technology (e.g., graphing software) and other tools. SIS4. Communicate and apply the results of scientific investigations.

-Develop descriptions of and explanations for scientific concepts that were a focus of one or more investigations. -Review information, explain statistical analysis, and summarize data collected and analyzed as the result of an investigation. -Explain diagrams and charts that represent relationships of variables.

III. Content to be Taught

A. Alcohol depresses the nervous system B. Alcohol causes the heart rate of Daphnia to decrease. C. A toxin is a substance can harm humans or animals and is related to

dosage.

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IV. Rationale The knowledge that alcohol has toxic properties and negatively affects the regulation of vital life processes deepens students understanding of the physiological consequences of alcohol use and abuse.

V. Goals

Students will understand that alcohol is a central nervous system depressant that has toxic properties.

VI. Objectives

Students will do the following: A. Measure the effects of alcohol on the heart rates of Daphnia B. Define toxicity as the property of a substance to substance to harm

humans or animals and is related to dosage C. Graph heart rate vs. alcohol concentration D. Interpret data to conclude that alcohol negatively affects the regulation of

heart rate in Daphnia

VII. Background for Teacher

Ethanol (Ethyl alcohol) is a central nervous system depressant that has a wide range of effects on the human body. It specifically affects the parts of the brain that control, thinking, coordination, and the control centers for heartbeat, breathing, and the gag reflex.

Although alcohol is a depressant, it is often thought of as a stimulant because it frequently causes decreased inhibition and increased pleasure seeking. Alcohol depresses a class of receptors in the brain known as GABA that impairs coordination, thinking, heartbeat, and breathing. Anterograde amnesia, also known as blacking out, may also occur.

Acute effects of alcohol in humans include increased heart rate at low blood alcohol concentration (BAC) due to the dilation of the blood vessels. As the BAC increases, the depression of the central nervous system causes the heart rate to decrease.

Chronic effects of alcohol intake include high blood pressure and cardiomyopathy. Dilated cardiomyopathy is serious condition of the heart muscles that causes heart chambers to become enlarged resulting in the decreased efficiency of the heart. The body compensates by increasing blood volume thus increasing blood pressure.

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Alcohol causes Daphnia heart rates to decrease providing evidence that alcohol acts as a depressant.

VIII. Engagement

A. Review the ADH lab.

1. Focus attention on the alcohol that is not broken down by ADH. 2. Ask, “What effects will the excess alcohol have on the body?”

B. Encourage the students to identify criteria for toxicity. Ask True/ False questions about whether bleach, cyanide, lead, and water are toxins (They all are toxic.). Develop a definition of toxic as - "the degree to which a substance can harm humans or animals and is related to dosage." (thefreedictionary.com).

C. Lead a discussion around the question, "Is alcohol a toxin?" This is the essential question for the lesson.

D. Ask, "What evidence would we need to determine whether alcohol is a toxin?"

1. Ans. Evidence that it harms organisms depending on dosage E. Ask "How can we test the toxicity of alcohol without using human

subjects?" 1. Ans. Use an animal model

F. Introduce the animal model Daphnia magna, as a model organism. Show the video of a Daphnia at (http://www.ebiomedia.com/Biology-Classics/The-Biology-Classics-Daphnia-Heart.html)

G. Project an anatomical chart of Daphnia (provided below). 1. Ask, "What part of the Daphnia could provide evidence to detect

the effect of alcohol on the organisms?" Suggest the heart. 2. Ask the students to predict the effect of alcohol on Daphnia heart

rate.

IX. Exploration: Toxicology Lab Protocol (Option: use the video of daphnia exposed to various concentrations of alcohol provided on this website.)

1. Present a picture of the crustacean Daphnia Magna. Emphasize

the following anatomical parts: Eye, Heart, Antennae, Brood Chamber with eggs, Intestine, and Legs.

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2. Show the video demonstration of the Daphnia heart beating (http://www.ebiomedia.com/Biology-Classics/The-Biology-Classics-Daphnia-Heart.html). Demonstrate how to determine the heart rate by counting the number of heart beats in 10 seconds and multiplying by 6 to obtain beats per minute.

3. Demonstrate the technique for preparing the Daphnia. We recommend letting the students prepare their Daphnia slides as you demonstrate.

a. Place a slide with a well depression on a level surface. b. Dip a cotton swab in the petroleum jelly. Make a water

barrier by coating the circumference of the well with the petroleum jelly.

c. Place a small dab of petroleum jelly in the center of the well. This will be to capture the Daphnia.

d. Place the slide on the microscope stage. e. Use a transfer pipette to pick up one Daphnia. Add the

Daphnia with one or two drops of water to the well to cover the Daphnia with water.

f. Wick away the water surrounding the Daphnia with a paper towel to immobilize the Daphnia in the center smear of petroleum jelly. Add 1-3 drops of spring water to the well to cover the Daphnia.

g. Turn on the microscope light and focus on the Daphnia using 40X magnification.

h. Turn the light off and wait one minute. The light emits heat that could affect the heart rate. Therefore minimize the amount of time the light is on.

i. Turn the light back on and record the number of heartbeats in 10 seconds. Turn off the light.

j. Multiply the number of heart beats in 10 sec by 6 and record the number of heartbeats per minute in the 0% alcohol row in Table 1.

k. Wait one minute and repeat step i and j two more times. l. Record the results in rows labeled Trial 2 and Trial 3 in

Table 1. m. Repeat steps f through l for the 4% and 8% alcohol

solutions. Be sure to rinse the Daphnia with spring water prior to applying a different concentration of alcohol.

Table 1

% Alcohol

Heart rate beats/min Avg.Heart Rate beats/per min Trial 1 Trial 2 Trial 3

0

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n. Have the students graph Average Heart rate vs. Alcohol Concentration (cf. the student data sheet).

X. Explanation A. Ask the students to propose their answer to the essential question, “Is

alcohol a toxin?” They must support their answer with data. B. Confirm that the evidence supports a decrease in heart rate with

increased alcohol concentration in Daphnia. Explain that alcohol has similar effects on humans. Acute effects of alcohol in humans include increased heart rate at low blood alcohol concentration due to the dilation of the blood vessels. Dilation increases the volume of blood vessels, therefore the blood pressure decreases and the heart needs to pump faster to move the blood throughout a larger volume. However as the blood alcohol concentration increases, the heart rate decreases due to alcohol’s depressant effect on the central nervous system that controls heart rate.

XI. Evaluation A. Ask the students to respond to the following:

1. What does the data suggest for a relationship between alcohol concentration and heart rate of Daphnia?

a. Answer: the heart rate decreases with increasing concentrations of alcohol

2. Predict what would happen to the Daphnia heart rate if you added 20% alcohol to the Daphnia?

a. Answer: the heart rate would slow down considerably. Students may extrapolate from the graph that the heart rate will slow considerably, even assigning a numerical value. They may also conclude that the heart rate will stop.

3. Explain whether the data supports the conclusion that alcohol is a toxin.

a. Answer: The data supports the toxicity of alcohol because it exhibits the potential to harm organisms as the dosage increases.

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XII. Appendix

Name____________________________

Student Data Sheet

Table 1. Daphnia Heart Rate Data

% Alcohol Trial 1 Trial 2 Trial 3

Avg.Heart Rate in 10 sec

0

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Average Heart Rate vs. Alcohol Concentration

% Alcohol Concentration

0                      4           8 

Average 

heart rate 

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Lab Prep for Daphnia Lab

A. Materials

Station Set-up- Each station will need:

1 depression slide (sticker side up)

1 plastic transfer pipette

1 p200 micropipette

1 tip box with tips

1 waste beaker

1 cotton swab

1 Petri dish with spring water and 3 Daphnia

1 tube of petroleum jelly

200 µl of an alcohol solution

1000uL spring water (0% ethanol)

1 timer

2 paper towels

I. Alcohol solutions

Make the alcohol solutions with an 80 proof clear alcohol such as vodka. Using lab ready denatured ethanol contains other ingredients such as methanol that will affect the Daphnia deleteriously.

Each group should receive 200 µl of the following solutions.

for 200 µl of solution

8% ETOH

4% ETOH

0% ETOH

µl of 80 proof (40%) Vodka

40 20 0

µl of springwater

160 180 200

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2. Daphnia

Daphnia can be ordered at VWR. If you purchase the Daphnia care kit, the Daphnia can be kept for up to six months. Make sure to change 10% of the water every week and replace it with spring water. Do not remove the detritus on the bottom as it contains Daphnia eggs that will sustain the population.

Sources:

http://www.ebiomedia.com/Biology-Classics/The-Biology-Classics-Daphnia-Heart.html

Carolina Protozoa and Invertebrates Manual, Carolina Biological Supply Company

http://www.sciencebuddies.org/mentoring/project_ideas/Pharm_p009.shtml. Andrew Oslen, PhD. April 1st 2008.

http://en.wikipedia.org/wiki/Blood_alcohol_content. September 15, 2009.

http://www.collegedrinkingprevention.gov/OtherAlcoholInformation/factsAboutAlcoholPoisoning.aspx#WhatHappens.

http://www.ou.edu/oupd/bac.htm. The Police Notebook. 9/17/09