人教版必修5第五单元课文.docVIP

必修5 Unit 5 First aid-Reading 　　FIRST AID FOR BURNS 　　The skin is an essential part of your body and its largest organ. You have three layers of skin which act as a barrier against disease, poisons and the suns harmful rays. The functions of your skin are also very complex: it keeps you warm or cool; it prevents your body from losing too much water; it is where you feel cold, heat or pain and it gives you your sense of touch. So as you can imagine, if your skin gets burned it can be very serious. First aid is a very important first step in the treatment of bums. 　　Causes of burns 　　You can get burned by a variety of things: hot liquids, steam, fire, radiation (by being close to high heat or fire, etc), the sun, electricity or chemicals. 　　Types of burns 　　There are three types of burns. Burns are called first, second or third degree burns, depending on 　　which layers of the skin are burned. 　　◎ First degree burns??? These affect only the top layer of the skin. These burns are not serious and should feel better within a day or two. Examples include mild sunburn and burns caused by touching a hot pan, stove or iron for a mordent. 　　◎ Second degree burns? These affect both the top and the second layer of the skin. These bums are serious and take a few weeks to heal. Examples include severe sunburn and bums caused by hot liquids. 　　◎ Third degree burns?? These affect all three layers of the skin and any tissue and organs under the skin. Examples include burns caused by electric shocks, burning clothes, or severe petrol fires. These burns cause very severe injuries and the victim must go to hospital at once. 　　Characteristics of burns 　　First degree burns 　　◎ dry, red and mildly swollen 　　◎ mildly painful 　　◎ turn white when pressed 　　Second degree burns 　　◎ rough, red and swollen 　　◎ blisters 　　◎ watery surface 　　◎ extremely painful 　　Third degree burns 　　◎ black and white and charred 　　◎ swollen; often tissue under them can be seen 　　◎ little or no pain if nerves are da