Many animals directly depend on the temperature of their surrounding environment to keep their bodies warm. If the temperature falls, their body temperatures will also fall, decreasing their efficiency and activeness. These types of animals are called cold-blooded animals or ectotherms. Reptiles, amphibians, and fish belong to this category. However, birds and mammals have different mechanisms to keep their body at a constant temperature despite changes in their surrounding environment. Because of this ability, they are called warm-blooded animals or endotherms. The process of maintaining their body temperature in a constant value is commonly referred to as homeostasis. Unlike cold-blooded animals, warm-blooded animals mainly use their food as the energy source for homeostasis. Therefore, the system is very expensive in terms of food energy.
The heat controlling mechanisms of the body in warm-blooded animals are mainly controlled by the brain (hypothalamus), which receives signals from the sense organs situated in the peripheral region of the body. These sense organs are very sensitive to temperature changes in the blood. Whenever they detect any change, the control center in the hypothalamus adjusts homeostasis mechanisms to maintain the heat balance of the body.
So, how does a warm blooded animal get body heat. Let’s take a look at that now.
How Does a Warm Blooded Animal Get Body Heat
Metabolism of food is the main method used by warm-blooded animals to generates heat. The energy obtained through the digestion of food is stored in the liver and muscles. Movements of muscles help to warm the body as they generate heat by increasing rate of respiration. In addition, if a warm-blooded animal rests in cold environment, its muscles begin to move automatically. This is known as shivering and is another way of warming the body of warm-blooded animals. Moreover, during the cold season, warm-blooded animals have higher metabolic rates due to the high demand of energy. This will ultimately increase the appetite for food during cold seasons.
Another way of getting body heat is the reduction of heat loss. Warm-blooded animals have developed various adaptations to retain heat or reduce heat reduction. Most of the warm-blooded animals have a fat layer beneath their skin that act as an insulation layer for heat reduction. The fat layer of mammals is made up of adipose tissue. In addition to providing heat insulation, the fat layer also acts as a store of food. Almost all mammals have hair on the skin to retain heat. Most of the warm-blooded animals that live in extreme cold condition have very thick hair and fat in order to provide them a better heat insulation. In birds, layers of feathers act as an insulation layer. In cold climates, the sweat glands of warm-blooded animals are closed in order to reduce the heat loss by evaporation. Another adaptation for prevention of heat loss is vasoconstriction, which is the restriction of blood flow near the body surface by reducing the diameter of blood capillaries.
These are the main mechanisms, which generate body heat in warm-blooded animals. Homeostasis is considered as a very important process in warm-blooded animals because even a small change of body temperature (about 2 °C change) can cause greater damage to the body system.
References:
Beckett, B. S., Biology: A modern introduction, GCSE edition, Oxford University Press.
Anita Ganeri, Animal Science, First Edition, Evans Brothers Limited, London.
Image Courtesy:
“Energy and life” By Mikael Häggström – (Public Domain) via Commons Wikimedia
