How do endothermic animals like seals and foxes ‘know’ that their body temperatu
ID: 49739 • Letter: H
Question
How do endothermic animals like seals and foxes ‘know’ that their body temperature needs to be adjusted?
When shivering starts they know it’s time to warm up
Nerve cells in their brains measure the temperature of blood and send signals to other cells and tissues if the temperature changes very much one way or the other
Reduced mobility, sluggishness, are all signs of too-low body temperature
Temperature-sensing cells in their extremities (eg, legs and feet) measure the environmental temperature and signal the brain that’s it’s time to change body temperature
1.When shivering starts they know it’s time to warm up
2.Nerve cells in their brains measure the temperature of blood and send signals to other cells and tissues if the temperature changes very much one way or the other
3.Reduced mobility, sluggishness, are all signs of too-low body temperature
4.Temperature-sensing cells in their extremities (eg, legs and feet) measure the environmental temperature and signal the brain that’s it’s time to change body temperature
Explanation / Answer
An endotherm is an organism that maintains its body temperature, largely by the use of heat set free by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly due to metabolism, but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production.
In endotherms, heat generation can warm the body as it dissipates throughout tissues and organs.
In all the endotherms including arctic foxes and seals, the process of recognition of surrounding cold or low temperature condition starts from the signals received by hypothalamus of brain. A small portion of the brain known as the hypothalamus is the thermostat that controls the body’s furnace. Nerves in the skin and deep within the body send temperature messages to the hypothalamus. The hypothalamus analyzes these readings or messages, and compares the temperatures of these areas with that of the brain, if necessary, it signals the animal to make appropriate changes to increase the heat.
In severely cold conditions, endothermic animals including arctic foxes and seals can produce more heat by augmented muscular activity through exercise or shivering. Every time muscle cell contracts, the actin myosin filaments sliding over each other, and the hydrolysis of ATP molecules generate heat. Both voluntary muscular work (e.g., running flying, jumping) and involuntary muscular work (e.g., shivering) generate heat. Heat generation by shivering is called shivering thermogenesis.
In addition, animals like arctic foxes and seals have rete mirabile ( a complex of arteries and veins lying very close to each other) in their extremities (e.g., tails, ears, and nose), which measure the environmental temperature and signal the brain that’s it’s time to change body temperature.
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