Temperature Regulation Biological Psychology Temperature

Temperature Regulation

Biological psychology

Temperature regulation: A function of the brain and the body

Temperature regulation: A function of the brain and the body

As warm-blooded animals, humans and other mammals and birds have a great advantage in temperature regulation. Unlike cold-blooded animals such as reptiles, insects, and amphibians, humans are capable of moving quite quickly in very cold temperatures. The human body is not dependant upon the environment to maintain a core temperature so the body's muscles can function effectively. 2/3 of human's total energy expenditure involves maintaining body temperature. We need more fuel as a species than a frog, but we are also capable of moving faster during cold weather to obtain higher-quality sources of protein and satisfy the needs of our many fast-twitch muscles (Kalat, 2008, p.293). Constant body temperatures and better-quality fuel may also have enabled humans to obtain enough nutrients to fuel greater brain cell activity as well.

However, humans are still quite fragile and are capable of functioning at an optimal level within only a relatively limited temperature range, as when temperatures exceed 41C, protein stability decreases (Kalat, 2008, p.295). But the higher the temperature, the more muscle activity can increase. Human's body temperature at 37C thus is considered an optimal compromise to maintain homeostasis. Slightly cooler temperatures are needed to maintain optimal fertility and ensure healthy fetal development (Kalat, 2008, p.293).

The brain plays a critical function in temperature regulation. The preoptic area and anterior hypothalamus (POA/AH) are critical for temperature control (Kalat, 2008, p.294). Cells react based upon the temperature of the hypothalamus -- if the hypothalamus 'feels' cold, so does the organism. Temperature receptors in the skin and spinal cord also affect sensation and animals react most strongly to temperature when both their temperature receptors and the hypothalamus are receiving similar types of stimulation.

Temperature, much like hunger is a homeostatic condition in which the body has a particular 'set point.' That set point can shift, depending upon environmental influences. For example, if someone is infected, a fever can actually help his or her body survive the disease, as certain kinds of bacteria grow less vigorously at high temperatures. Cytokines attacking the intruders send signals to the hypothalamus to release prostaglandins to 'give' the person a fever. Even if the person moves to a cold room, the fever will persist, and the body will work harder to maintain its high temperature (Kalat, 2008, p.294).

Newborn animals such as rabbits will often instinctively move to a warmer place if infected, as their bodies are too immature to demonstrate the involuntary response of a fever. Temperature modification is based upon involuntary biological mechanisms but also instinctual behavioral changes that have other evolutionary sources. Some of our involuntary and voluntary human mechanisms include shivering, huddling together with other warm creatures, moving towards the warm sunlight, and getting goosebumps to 'fluff' one's fur when cold (Obviously, the more fur an animal possesses, the more effective this mechanism can be). Similarly, in hot weather, seeking out sources of water, becoming less rather than more physically active, and sweating are all common behavioral adaptations.