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# Warm-Blooded: How Is Water Used to Lower an Animal’s Body Temperature?

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Source:
Author: Janice VanCleave

### Problem

How is water used to lower an animal's body temperature?

### Materials

• Marking pen
• 2 clear glasses
• Water
• 2 thermometers
• 1 bowl freezer

### Procedure

1. Use the masking tape and marking pen to label the glasses #1 and #2.
2. Fill both glasses one-half full with warm water from a faucet.
3. Place a thermometer in each glass.
4. Allow the glasses to stand undisturbed for one minute.
5. Read and record the temperature shown on each thermometer.
6. Set glass #1 in the bowl.
7. Add cold water from the faucet so that there are about 2 inches (5 cm) of water in the bowl.
8. As soon as the cold water is in the bowl containing glass #1, place glass #2 in the freezer and shut the door.
9. At the end of one minute, read and record the temperature shown on each thermometer.

### Results

The temperature of the water in glass #1 decreased more quickly than did the temperature of the water in glass #2.

### Why?

The body temperature of a cold-blooded animal changes with the temperature of its environment, but a warm-blooded animal maintains a constant body temperature regardless of the temperature outside its body. To regulate its temperature, a warm-blooded animal must increase heat loss from its body in hot weather and reduce heat loss during cold weather. One method of increasing heat loss is by bathing, wading, or standing in cold water. The water conducts heat from the animal's body more rapidly than does air. Your experiment demonstrated that heat energy in the water inside glass #1 moved out into the cooler water surrounding the glass. Heat energy in the water inside glass #2 also moved out into the air surrounding the glass but at a slower rate. This movement of heat energy from one substance to the next is called conduction. Water is a faster conductor of energy than air is.

### Let's Explore

1. Would moving water affect the rate of cooling? Repeat the experiment using a wooden spoon to stir the water in the bowl. Would animals be cooled faster in a running stream or still pond?
2. Would placing icy water in the bowl have affected the rate of cooling? Repeat the experiment placing ice cubes in the bowl of water.

### Show Time!

1. Are there other methods of increasing heat loss from the body of animals? The hypothalamus (a part of the brain) activates nerve impulses that relax the walls of small arteries in the skin. This allows more blood to circulate to the surface of the body. Demonstrate that larger blood vessels allow more blood to pass through by using two coffee cans with plastic lids. In the lid of can #1, punch two small holes. In the lid of can #2, punch one small hole and a large hole. Half fill both cans with water and secure the lids. Measure the time it takes to fill a 5-ounce (150 ml) bathroom cup by pouring the water from can #1 through one of the small holes in the lid. Then measure the time it takes to fill another bathroom cup by pouring the water from can #2 through the large hole in the lid. The results along with diagrams and/or pictures taken during the experiment can be used as part of a project display.
2. How do animals conserve body heat when the environment is cooler than their body temperature? Cats, dogs, and bears are examples of animals that reduce exposed surface area such as their noses by curling into a ball. Warm air from their nose moves under and around the body. Humans often warm the exposed skin on their hands by blowing on them. Breathe onto the bulb of a thermometer to measure the warmth of your exhaled breath.
3. Birds tuck their legs under their feathers to cut down on heat loss during cold winter days. Sudden chills cause animals with hair to have "goosebumps" on their skin. These bumps raise the individual hairs, capturing air that better insulates the skin. Discover other methods of how warm-blooded animals regulate their body temperature to keep it constant. Use diagrams or photographs to display this information.

### Check It Out?!

The hypothalamus is the temperature regulator in warm-blooded animals. It has sensory cells that detect changes in blood temperature. Find out more about the functions of this special section of the brain.