Panting as a thermoregulation strategy
Organisms must regulate their internal environment to external environment like body temperature, water balance, and pH value. It is called homeostasis, the maintenance of a relatively constant internal environment in a varying external environment. Thermoregulation is an example of homeostasis in action. When the temperature of the environment rises, sensory mechanisms in the skin detect the change. They send a message to the brain, which automatically analyze the message, induce sweating, or stimulate behavioral responses (Smith, 2009).
Definition of Panting
Panting is one of responses triggered by the thermoregulator centers of the brain in order to release body heat. When the blood becomes overheated, the brain will release signals and initiate panting. Air is inhaled; cooling the surface of the lungs and exhaled losing heat. Many lower Mammals, like dogs or birds, breathe through the mouth in most instead of through the nose because their body surfaces are covered with fur and the skin is supplied little sweat glands.
The phenomenon of panting produces a one-way air flow over the mouth, trachea, and bronchi to lose heat; heat is carried away in exhalant air from the lungs through evaporating water. In a definition, panting can achieve an increase in respiration frequency with a reducing rate of tidal volume. It can stabilize the requirements for gas exchange and pH homeostasis in order to avoid some negative changes in alveolar ventilation (Schmidt-Nielsen, 1997).
High Energetic Efficiency in PantingThe energy cost of panting is lower than expected, which revealed by Hales, who compared the distribution of cardiac output in a blood flow of respiratory muscles during panting accompanied by a reduction in flow to some of the nonrespiratory muscles (Robertshaw, May 4, 2006). In additions, panting can increase secretions of salivary in the mouth, and most of water is not evaporated by panting is swallowed and conserved back to the body (Schmidt-Nielsen, 1997). Kangaroo has three special strategies for energy saving to reduce its body heat: saliva spreading and panting at rest and sweating during exercise (Robertshaw, May 4, 2006).
Panting is a Primitive Strategy of the Early Mammals
Panting is a simple function to maintain the body temperature in early small mammal’s evolution. Small mammals have a small heat capacity, and their bodies will fluctuated rapidly by affecting the external temperature. To survive, small mammals must stay out of heat and drink water, so panting is a easy way for them to keep water balance and cool their bodies down (Schmidt-Nielsen, 1997).
- Robertshaw, D. (May 4, 2006). Mechanisms for the control of respiration evaporative heat loss in panting animals. Journal of Applied Physiology, doi:10.1152.
- Schmidt-Nielsen, K. (1997). Animal Physiology. Adaptation and Environment. US: Cambridge University Press.
- Smith, T. M. (2009). Elements of Ecology. In Chapter 7, Animal Adaptations to the Environment (p. page 149). New York: Benjamin Cummings.