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 Homeostasis or Why Dogs Pant

Homeostasis or Why Dogs Pant
Reading Level
     edHelper's suggested reading level:   grades 5 to 8
     Flesch-Kincaid grade level:   7.22

Vocabulary
     challenging words:    Ecto, ectothermic, Ectotherms, Endo, endothermic, endotherms, homeostasis, mouth-open, stability, sun-heated, therm, tongue-hanging, internal, lowers, disadvantage, fairly

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Homeostasis or Why Dogs Pant
By Cindy Grigg 		  
1     Have you ever wondered why your dog pants on hot days? It's because your dog is trying to maintain homeostasis. Homeostasis is a word that biologists use to describe how a living organism regulates its internal environment to maintain stability. One very important part of homeostasis is body temperature. On any particular day, the temperature might change by as much as 50º. In order for an organism's chemical reactions to continue as they should, the temperature on the inside of the organism needs to remain the same.
 
2     How do living things maintain homeostasis? When your body temperature begins to rise, what happens? You begin to sweat. Sweating is your body's way of cooling down, thus maintaining homeostasis. As the liquid dries on your skin, it cools your skin and lowers your temperature. Because dogs do not have sweat glands, they pant. Dogs have just a few sweat glands in their paws, so no matter how much they sweat; sweating could never cool them off. That's where the tongue-hanging out, mouth-open dog panting comes in.
 
3     The major blood vessel in a dog's head runs very close to the surface of its nose. The fresh air a dog breathes works like a fan to cool the blood in the nose, which then circulates through the dog's body to cool the rest of the body. The dog then exhales the warm air out its mouth.

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