Body Temperature, Energy and Heat Loss

A clinical thermometer should maintain its reading (be maximum reading) so that the value does not change when it is removed from the measuring site.

“Feeling colder” is somewhat subjective. Placing a warm hand against a steel block at a lower temperature will make the hand feel cold as heat flows from the hand to all parts the steel block. Wood does not produce this feeling as it conducts heat poorly so the hand will soon warm up the wood in contact with it. Choice C will happen only slightly as the wood block is a poor conductor of heat.

If more energy is expended than is taken in as food, the body will use some of its energy stored as fat, to make up the difference. Hence the percentage of body mass that is fat will decrease.

Vasoconstriction limits the amount of blood (at 37) that flows near the skin which allows the skin temperature to approach that of the surroundings.

All objects radiate IR rays. If our body temp is greater than that of our surroundings, we will radiate more than we absorb from the surroundings. It is the body surface area, not the amount of bare skin, that determines the amount of energy radiated.

“Basal” metabolic rate refers to the minimum amount. This occurs when there is no movement (apart from breathing and cardiovascular movements) and little mental activity.

Radiation will occur whether the skin is covered by clothing or not.

A cold wind cools us by convection. It continually removes the air that has been warmed by contact with the skin.

In this case, “clothing” the object in an insulator will prevent air convection from carrying away the warm air in contact with the hot object. Hence cool air is prevented from replacing the heated air.

The heat that transfers from the bruised part is used to break the bonds between adjacent water molecules to melt the ice, rather than to increase the kinetic energy of the molecules. Temp measures the average kinetic energy of the molecules. Hence temperature does not rise until all the ice has melted.