For discussing the functions of different structures of all organisms.
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Well, adipose tissue is known to act as a thermal insulator.
1) Why do body organs need thermal insulation?
2) How does adipose tissue provide it? Is it a property of fat stores or something?
The adipose tissue contains less water and blood vessels than most other tissues in the body. Thus, it conducts heat less efficiently, helping it to be retained in the core organs. Also, low blood flow amounts to lesser heat loss. In order to reverse this in hot environments, the surface blood vessels and capillaries of the skin dilate, facilitating better heat loss (coupled with sweating).
The function of most organs in mammals is severely compromised if the deep body temperature gets lower from the optimal and thus it is essential that we have means to keep us warm when it is cold. For us humans, clothes serve as the most important way of thermal insulation, and for many land mammals the primary insulator is the fur. However, when you look at the marine mammals you can definitely see the importance of fat as a thermal insulator: whales, seals and such can live in freezing cold waters because of the thick layer of blubber (fat) under their skin. Although blubber has more vascularization than normal adipose tissue, their diameter is controlled in a similar manner as in the skin: blood vessels are dilated when heat loss is required and contracted when it must be prevented. A human would become hypothermic within minutes and die soon after in a similar environment.
I am not certain to what extent animals sweat, but I know that many mammals are capable of sweating to some extent. However, pretty much only in humans (and perhaps in some other primates?) it is a major way of cooling. I also read somewhere that horses sweat as a means to cool down. Most mammals have few sweat glands and they are probably for other purposes (secreting pheromones or other such substances).
Dogs and cats (and even crows!) pant if they are getting too hot. Kangaroos lick their arms to cool themselves and so forth. The ways are many :)
I guess you could say that we humans are specialists in sweating!
answer1:Body organs of endotherms need to operate at the normal body temperatures of these animals, because they evolved to operate at those temperatures. The enzymes they have would not operate efficiently or they would not operate at all at lower temperatures. One of the major reasons people die from hypothermia is major organ failure.
Fat is a good natural insulator, as is air. It is just one of their inherent properties. Adipose tissue is fatty tissue.
answer2:Adipose tissue is now recognised as a highly active metabolic and endocrine organ. Great strides have been made in uncovering the multiple functions of the adipocyte in cellular and molecular detail, but it is essential to remember that adipose tissue normally operates as a structured whole. Its functions are regulated by multiple external influences such as autonomic nervous system activity, the rate of blood flow and the delivery of a complex mix of substrates and hormones in the plasma. Attempting to understand how all these factors converge and regulate adipose tissue function is a prime example of integrative physiology. Adipose tissue metabolism is extremely dynamic, and the supply of and removal of substrates in the blood is acutely regulated according to the nutritional state. Adipose tissue possesses the ability to a very large extent to modulate its own metabolic activities, including differentiation of new adipocytes and production of blood vessels as necessary to accommodate increasing fat stores. At the same time, adipocytes signal to other tissues to regulate their energy metabolism in accordance with the body's nutritional state. Ultimately adipocyte fat stores have to match the body's overall surplus or deficit of energy. This implies the existence of one (or more) signal(s) to the adipose tissue that reflects the body's energy status, and points once again to the need for an integrative view of adipose tissue function.
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