Animal Physiology Extensions
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ANIMAL PHYSIOLOGY EXPERIMENTS

These are extensions used to support Lab 10 in the AP Biology Laboratory Manual.

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The experiments given on this page pertain to

  1. The overall energetics of the physiology of a cold-blooded animal
  2. Measuring the rate of human nerve transmission
  3. The effects of temperature on human nerve and muscle reaction

TERMITE ENERGETICS

..... You have seen in the extension of Lab #2 (Enzymology) that the highest energy barrier over which a single reaction must proceed is not too difficult to measure, thanks to inciteful thinking by one Svante Arrhenius, who showed that Eact> was proportional to minus 2 times the slope of a plot of ln (rate) versus 1/T°K. ..You have also learned that the highest energy barrier that must be overcome in a long series of reactions is NOT the sum of the Eact's, but rather is simply the largest Eact. ..So let's get really complicated and see just what makes an animal "tick". ..What is its highest energy barrier as it wrestles with staying alive.

..... Choosing the model animal. ..Two qualities are needed. ..One is that the animal is cold-blooded so that we can adjust its temperature. ..The other is an animal that readily avails itself to its study. ..We are choosing the termite* because it is cold-blooded, easy to come by (ask your local exterminator), and can be made to do the right trick at our whim. ..You see, termites like to follow RED lines drawn only by Papermate® ball-point pens! ..All that is needed is a measured circular racetrack, upon which a small platoon of termites will go round and round. ..Thus as a preliminary check, just draw a circle upon a piece of paper using a RED Papermate® ball-point pen. ..Place a few termites in the center of the circle and watch.

..... Once the termites start marching around the circle begin your timer and determine how many times they go around the circle in a minute. ..As we saw in the Catalase Kinetics experiment regarding the determination of Eact, the units of measurement are not important.** ..So merely determining how many rounds they make in a minute is a respectible unit of measurement.

*termites are not a risk factor if they get loose in your school or home. ..You will be working with "workers", which cannot lay eggs and multiply. ..If any of your termites get away, they will not last very long as they require rather high humidity, and, being a colonial animal, but have their nest with a queen.

**When converting from one type of measurement to another, a multiplier is required. ..Since our Arrhenius graph must be multiplied, and since the graph is logarithmic in that direction, multiplication of a line under these conditions amounts to moving the line to either above or below your previous line. ..Since the lines will be parallel, and since the slope is all that really matters, you see that it doesn't matter what the rate units happen to be.

Setting Up the Termite Race-Track

..... The main trick here is to find some way to adjust the temperature of the race track. .. Let's see if these items can work together:

DIRECTIONS

  1. First paint the bottom of the inside of the aluminum pan, and let the paint dry for several days (to out gas any confusing smells).
  2. Tape a thermometer lengthwise down the center of the pan so that you can see the temperature.
  3. Visit your local exterminator to place an order for several dozen termites in a bottle.
  4. Draw an oval with the red pen on the white painted surface, but stay away from the thermometer.
  5. For initial, room-temperature run: ..dump some termites into the pan near the thermometer, cover the pan with the plastic wrap. ..Once a few of the termites start following the line, start timing how many laps they make in a minute. ..After you have run and recorded several successful races, dump the termites back into their bottle.
  6. With the start of each successive race, carefully draw another red oval atop the previous one(s). ..This is to keep the pheromone scent trail fresh. .. Cover the pan with plastic wrap.
  7. Now put a couple of inches of cold water in the bathtub, and float the covered pan on the water. .. In a few minutes the temperature in the pan should have equilibrated.
  8. Once the temperature is steady (record it!), dump in a few termites, and run a few races keeping records of how many laps they make in a minute.
  9. Do this for temperatures from about 10°C to about 45°C
  10. Construct a graph of speed versus temperature. ..Does it look reasonable? .. Do cold termites move slower than warmer ones? .. Is there a temperature above which the insects begin moving slower again?
  11. Then construct your Arrhenius Graph as was done in the Catalase Kinetics experiment. .. (A hint you might consider to get a more pleasing graph is to go back to the speed versus temperature graph and draw a smooth "best fit" line, and then get derived data points from it to use in constructing your Arrhenius Graph.)
  12. You will derive an Eact for the highest energy barrier that had to be over-come by the termites in this particular activity of walking. ..Now write up your report. You might want to follow the common journal format that is used world-wide. ..For an example, see one on Columbus. ..Why couldn't you do this with a warm-blooded animal?)

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RATE OF NERVE TRANSMISSION

..... In this exercise, the speed of nerve transmission is correlated with reaction rate. .. Fundamentally, the experimenter dangles a meter stick from its upper end so that its lower end is between the subject's fingers and thumb as the participant is posed to catch it. ..Once the stick is dropped the participant clamps the hand shut to catch it. ..The distance the meter stick has fallen is recorded. .. There are a number of variations on this. .. Each variation is an attempt to change the length of the nerve path between the control center in the brain and the hand.

  1. Using sight: ..the subject sees the stick begin to fall and then grabs it.
  2. The participant's eyes are kept closed and the stick is dropped at the instant the experimenter taps them on the head (this requires the experimenter to practice a bit!). ..In this experiment, is the nerve distance the same as that when using the eyes? ..Is sight dominant over touch?
  3. The subject's eyes are closed, and the "go" signal is a tap on one or the other shoulder. .. Now how long is the nerve pathway? ..(Shoulder to head to hand.)
  4. Again the subject's eyes are closed, and the "go" signal is a tap on the other hand. .. Now how long is the nerve pathway?
  5. Again the subject's eyes are closed, and the "go" signal is a tap on a foot. .. Now how long is the nerve pathway?

..... Central to your results will be a graph of reaction time versus the length of the nerve pathway. ..You may also wish to do the next experiment which introduces variations in temperature.

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The effects of temperature on human nerve and muscle reaction

..... This is a rather straightforward modification of the preceeding exercise. ..Indeed, data from that exercise can act as the "control" for this one.

..... Although humans are homeotherms (warm-blooded), parts of our bodies can have their temperatures changed quite considerably. ..Take fingers, for example. We have all had cold fingers, and know that when they are cold they are stiff and sluggish. .. In this exercise, hands and lower arms will be pretreated to different temperature regimes and then quickly subjected to testing using the foregoing procedure. ..Thus the subject has either an ice-water chilled hand or a warm-water heated hand. ..Before final reports are given, debate between students should consider how to treat findings when only part of the nerve pathway will be affected.

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