Thermoregulation Concept Mapping

The following information is the minimum you need to know about thermoregulation. Transfer this information to a concept map. You must include the negative feedback loop at the end of this handout, but you can also include pictures, connectors, lines, whatever… I will grade the concept map and if yours is worthy, I’ll let you use it on the next test!

Definition:

Thermoregulation is the ability to either keep the body temperature constant or to develop a life style that permits survival over a range of internal temperatures. Animals are subject to environmental changes and adapting to those changes is necessary for homeostasis.

Two types of thermoregulators:

  1. Ectotherms: cold-blooded (poikilotherms) that absorb

heat from their surroundings.

  1. Fish
  2. Amphibians
  3. Reptiles

Examples of Ectothermic Regulation

  • Invertebrates: shivering to warm up flight muscles (moths), butterflies orient themselves to absorb maximum sunlight.
  • Fish: use counter current exchange which means that the arteries and veins run side by side. Arterial blood is warmer than venous blood. The warmth from the arteries is transferred to the veins and also to the muscles.

Move to an appropriate temperature depth in the water.

  • Amphibians: Lose a lot of heat through evaporation. They can sun themselves as well as find warm locations in a body of water or underground.
  • Reptiles: Sun bathing or avoiding sun, depending on their climate. Can change skin color to absorb more sunlight. Horny toads can darken their skin to absorb more light.

II. Endotherms: warm-blooded (homeotherms) maintain a

constant internal temperature.

  1. Birds
  2. Mammals (give two examples)

Examples of Endothermic Regulation

  • Birds:
  • Feathers insulate
  • can pant to promote evaporative heat loss
  • legs lose a lot of heat
  • counter current heat exchange reduces heat loss in the legs when arterial blood warms the venous blood
  • birds puff up their feathers
  • Mammals:
  • when mammals are cold the blood vessels constrict (vasoconstriction) to conserve heat, by reducing sweat production
  • when mammals are warm, the blood vessels dilate (vasodilation) to release more sweat so it can evaporate
  • fat insulates
  • hair can stand on end to warm the mammal
  • muscles will shiver to produce heat
  • shedding in summer months
  • panting and sweating
  • hiding or migrating when it is hot
  • Desert mammals: large ears allow more heat to escape the body, hiding or migrating when it is hot, active during the night when it is cooler, camels fat storage in the hump
  • Arctic mammals: thick fur and layers of fat for insulation

Mammalian Methods for Thermoregulation: (See image on the next page.)

Sensory neurons on the skin’s surface pick up the temperature through thermoreceptors. The sensory neurons send the temperature message to the hypothalamus. The hypothalamus also picks up the blood’s temperature. If it is cold, hormones like thyroid stimulating hormone TSH will be produced by the anterior pituitary and they will travel to the thyroid to increase thyroxine production. This will increase metabolism and warm the body. If it’s too hot, the brain will send the message to the blood vessels to dilate, the muscles to shiver, and the mouth to pant.