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MCAT Content / Respiratory System / Thermoregulation Nasal And Tracheal Capillary Beds Evaporation Panting

Thermoregulation: nasal and tracheal capillary beds; evaporation, panting

Topic: Respiratory System

Thermoregulation occurs via the blood capillaries in the capillary beds of the nasal tract by bringing blood close to the outside world, enabling loss of heat from the blood. In dogs, panting is the primary mechanism to regulate body temperature.

Thermoregulation is the control of the bodies temperature. Thermoregulation is controlled by sweating from the skin and loss of heat through expired water vapour, but the capillaries of the nasal bed and tract also play a role. When the capillaries present in the capillary beds of the nasal tract and tracheal wall dilate, the flow of blood to the tract lining increases releasing more heat to the surroundings. Conversely, when the capillaries constrict, the flow of blood to the tract lining decreases, reducing heat loss. This does not play a significant role in the thermoregulation of the body; however, due to the small amounts of heat energy lost or reserved.

However, in animals like dogs, heat is lost when they take out their tongue from the mouth, which is known as panting. This is the dogs only method of releasing excess body heat as it allows for the evaporation of water and heat from the moist surfaces of the lungs and tongue.

Key Points

• Vasoconstriction warms the body by reducing heat loss from the blood vessels of the tracheal and nasal capillary beds. Vasodilation cools the body by increasing heat loss from the blood vessels.

• Major thermoregulation takes place by evaporation of heat in the form of sweat from the capillaries of the skin.

• The release of heat from the tongue, such as in dogs, to regulate body temperature is known as panting.

Key Terms

constrict: become narrow

dilate: become wide

thermoregulation: the regulation of heat dissipation from the body

panting: the exposure of a dogs tongue to the surface to increase heat loss

capillaries: one cell thick small blood vessels that join arteries to veins

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