Body Temperature, Energy and Heat Loss
One of the following mechanisms for losing body heat does NOT increase heat loss as we increase the amount of bare skin that we expose. Which one?
Respiratory heat loss
Heat loss by conduction
The evaporation of sweat
Heat lost through convection
Respiratory heat loss
Respiratory heat loss occurs because the air we inhale is usually at less than 37 ยฐC, while it is warmed to 37 ยฐC before it is exhaled. (Also exhaled air is saturated with water vapour that carries with it the heat of vaporisation.) These mechanisms are not affected by the amount of skin we expose.
Respiratory heat loss Respiratory heat loss occurs because the air we inhale is usually at less than 37 ยฐC, while it is warmed to 37 ยฐC before it is exhaled. (Also exhaled air is saturated with water vapour that carries with it the heat of vaporisation.) These mechanisms are not affected by the amount of skin we expose.
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The Systรจme International (Standard International) unit of power is the watt. This unit is the same as which one of the following?A. Electronvolt
B. Joule
C. Joule per second
D. Kilojoule
Which of the following correctly states the principle of conservation of energy in terms of the human body? (Assume no foodstuffs are consumed and no urine or faeces are excreted.)
A. Q = s ร m ร ฮT (Q = energy, s = specific heat of tissue, m = body mass, T = body temperature)
B. The energy stored in the human body is equal to the energy lost from the body plus the work done by the body.
C. The energy value of the food we eat must exceed the energy value of the muscular activity we perform.
D. The change in the energy stored in the body is equal to the heat lost from the body plus the work done by the body.
On a normal winter day, by what means does the human body lose most of its heat?
A. Convection
B. Conduction
C. Radiation
D. Evaporation
Which one of the following statements does NOT accurately describe energy?
A. Energy can be created but not destroyed.
B. The total amount of all types of energy remains constant.
C. The energy gained by an object is the amount of work done on the object.
D. Energy is the heat given out when oxidation occurs.
Which choice explains how the evaporation of sweat “cools” our body?
A. Evaporating water molecules carry with them more than the average amount of kinetic energy which leaves the remaining molecules with a lower average kinetic energy.
B. The body loses more heat through the infrared radiation emitted by sweat than it gains from the infrared radiation emitted by the surroundings.
C. Sweat is at a lower temperature than our core body temperature so sweat on our skin cools us by conduction.
D. The water molecules in sweat are at a higher temperature than our core body temperature so losing sweat leaves us cooler due to the mass of water lost.
In which situation will the evaporation of sweat from the skin be ineffective as a heat loss method?
A. The air temperature is greater than human body temperature.
B. The air temperature is less than human body temperature.
C. The surrounding air is saturated with water vapour.
D. The human body is immersed in the water of a swimming pool.
What is the most effective way to deposit heat in bones and joints?
A. Ultrasound
B. Infrared radiation
C. Conductive heating (heat packs)
D. Diathermy
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