The temperature of your body should be always just the same,no matter whether the weather is hot or cold. That is why the doctor uses his thermometer when you are sick.
The body keeps the same temperature all the time,because it balances the heat it produces and it gives off. It is always burning up food and producing heat. It can produce heat faster when it needs to give off heat than when it becomes too warm.Let's see how this happens.
The heat of your body is given off mainly through the skin. When you are cold,your skin is tight and shows“good flesh”. When you get chilly,you must dance around to keep warm or else you will shiver(颤抖). Then your muscles begin to work,burn up fuel,and produce more heat. It is not pleasant to shiver,so you usually prefer to warm up by exercise,or put on more clothes to keep heat in.
When you are warm,the skin is loose and soft. It is so supplied with blood that heat is given off rapidly. If you get too warm,you begin to sweat,and more body heat is used in evaporating(蒸发) the moisture(湿气) from your skin. You wear less clothing,too,in warm weather a warm room,so that warm can be given off freely.You feel less like exercising because your body is warm already,and the extra heat produced by exercise makes you uncomfortable.
You can see from the way you feel differently in different kinds of weather. In summer,when it is warm,you feel tired and lazy. You do not care to work or play,but enjoy lying and doing nothing. When you get out of doors in winter,the cold air makes you feel lively. You want to play.
2. When one feels chilly,which of the following will he do?
A His skin becomes tight in order to keep warm.
B He does exercises to make his muscle produce more heat.
C He puts on more clothes to produce heat.
D He keeps shivering to produce more heat.
