初中英語聽力天冷不宜鍛煉

初中英語聽力：天冷不宜鍛煉D:Woo……It”sfreezingout.

Y:Comeon,It”snotthatcold.

D:Sureitis.Yael.Iguessthere”sjustnowayIcangojoggingtoday.

Y:Oh,sothat”swhatthisallabout.

D:Notreally.Whatifmylungsfreeze?

Y:Actually,yourbodyisdesignedsothatbythetimeairreachesyourlungs,it’sbeenwarmedupandmoisturizedbyyournasalpassages,throat,andtrachea.Besides,thebloodsupplyinyourlungsissowelldevelopedthatthere’svirtuallynowaytheycanfreeze–thecirculatingbloodkeepsthemniceandtoasty.

D:Oh,yeah.Sowhydoesithurttobreathethisreallycold?

Y:Well,whentheairisfrigid,itdoesn’twarmupsufficientlybeforeitreachestheairwaysleadingtoyourlungs,andsoitshocksthesurroundingmusclesandcausesthemtocontract.This,inturn,causesyourbronchialtubestocontracttoo,whichresultsinthattight,pricklyfeeling.

D:Uh,soundsdangerousespeciallywhenyouexerciseinbreathetoyourmouth.Whatifmytonguefreezes?

Y:Well,Don.Unlessyousufferfromasthma,breathingincoldairwon’thurtyou–andyou’dhavetoworryaboutfrostbitetoyourfingersandtoeslongbeforeworryingaboutyourtonguefreezing.

D：哇，外面太冷了。

Y：不會吧，沒那么夸大。

D：的確很冷啊。我想今日也沒方法跑步了。

Y：原來你是不想熬煉。

D：也不完全是。假如我的肺結(jié)冰了怎么辦?

Y：實際上，我們的身體是有應(yīng)對措施的。當(dāng)空氣進入肺部之前就已經(jīng)被鼻腔，喉嚨和氣管加濕，加熱。另外，肺部里的血液供應(yīng)很充分，幾乎沒有可能結(jié)冰-——血液循環(huán)讓肺部保持正常和舒適。

D：是嗎?那為什么在呼吸冷空氣時會痛苦?

Y：由于在嚴寒的空氣到達通向肺部的氣管時還沒有得到充分的熱身，所以沖擊到四周的肌肉使其收縮。轉(zhuǎn)而使得支氣管收縮，因此你就會有緊繃刺痛的感覺。

D