Varieties of Homeostasis

Homeostasis describes the ability of an organism to maintain a consistent internal environment. The Dynamic Energy Budget (DEB) theory for metabolic organization offers a simple, quantitative explanation for homeostasis by focusing upon structure and metabolic processes. The DEB theory identifies five varieties of homeostasis, according to Dr. S.A.L.M. Kooijman.

Strong

• Strong homeostasis describes the strict chemical consistency of generalized compound pools within the organism's body. These pools include lipids and polymers such as carbohydrates and proteins. These pools and the overall structure do not change in chemical composition but they can vary in quantity, which permits the organism to engage in whole-body change. Strong homeostasis can be found in all living organisms.

Weak

• Weak homeostasis contends that an organism's whole composition maintains consistency as long as the quantity of ingested substrates remains constant. Weak homeostasis continues even if the organism is growing. However, if the quantity of the substrate varies, then the composition of the individual will vary. Like strong homeostasis, weak homeostasis occurs in all living organisms.

Structural

• Structural homeostasis maintains that an organism's internal substructures grow and develop in a proportion consistent with their relationship to the overall structure. As a result of structural homeostasis, the individual maintains a consistent shape while growing. For example, a child's growth is characterized by the enlargement of internal organs that are the right size necessary to maintain the growing body. Structural homeostasis is important because it maintains the surface area ratios of the body's different structures, which regulate the transportation of substrates through the body.

Thermal

• Thermal homeostasis is the body's ability to regulate and maintain its temperature. Mammals and birds possess this ability to a strong degree. Humans, for example, maintain an average body temperature of 98.6 degrees Fahrenheit, and their internal body temperature does not change with variations in the weather. In fact, significant deviations from the internal norm can cause serious health problems. In contrast, cold-blooded animals, such as frogs and some lizards, are unable to maintain their internal temperature without the existence of an external heat source. As a result, their internal temperatures closely mirror the temperature of the outside environment.

Acquistional

• Acquisitional homeostasis describes the consistent rate of feeding practiced by an organism. Acquisitional homeostasis functions independently of the supply of food available. This type of homeostasis is largely limited to animals high in the food chain.