IGCSE生物考試難點(diǎn)解析

馬上就要迎來IGCSE和A-Level的大考了，在這里，Leon老師給大家?guī)砹薎G生物中的難點(diǎn)干貨分享——心臟作用以及相關(guān)答題技巧。在這個(gè)知識(shí)點(diǎn)的學(xué)習(xí)中學(xué)生通常遇到的問題是：心臟供血的生理過程比較復(fù)雜，

課本上給出的東西比較散亂，不容易記憶，

因此在這里L(fēng)eon老師會(huì)幫助大家總結(jié)出較好的關(guān)鍵詞去回答問題，這樣就可以避免答案冗長卻沒有重點(diǎn)的問題，希望Leon老師總結(jié)出來的干貨對(duì)大家的考試有所幫助。

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相關(guān)概念總結(jié)

一、 雙循環(huán)系統(tǒng)及其作用：

雙循環(huán)系統(tǒng)：

The right side of the heart collects deoxygenated blood from the body and pumps it to the lungs.右側(cè)集中了無氧血，會(huì)進(jìn)入肺部攜帶氧氣并將二氧化碳排出體外。The left side collects oxygenated blood from the lungs and pumps it to the body.左側(cè)則主要集中了含氧血，將會(huì)進(jìn)入全身循環(huán)供給各個(gè)組織（Tissue）氧氣以維持呼吸作用。This is called a double circulation system, because the blood travels through ?the heart twice on one complete journey around the body。所謂雙循環(huán)系統(tǒng)就是血液需要兩次進(jìn)入心臟。作用：Oxygenated blood is kept separated from deoxygenated blood and the septum（隔膜） in the heart ensures this complete separation, which will increase the respiration rate.有氧血和無氧血被隔膜完全分開，雙循環(huán)系統(tǒng)可以提高呼吸作用效率。

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心臟結(jié)構(gòu)以及供血過程：

首先給大家把這些專有名詞的意思以及功能作出解釋：血管類Superior vena cava上腔靜脈 ?and Inferior vena cava下腔靜脈——deoxygenated blood flows back through vena cava to right atrium.無氧血通過腔靜脈進(jìn)入右心房。Aorta主動(dòng)脈——help pump oxygenated blood to our body.主動(dòng)脈輸送血液至全身。Pulmonary artery肺動(dòng)脈——help pump deoxygenated blood to lung for oxygen.將無氧血輸送至肺部。Pulmonary vein肺靜脈——Oxygenated blood flows back to left atrium含氧血通過肺靜脈進(jìn)入左心房。房室Atrum心房——collect deoxygenated blood from Vena cava and oxygenated blood form pulmonary vein.儲(chǔ)存來自腔靜脈的無氧血以及來自肺靜脈的含氧血。Ventricle心室——pump the deoxygenated blood to lung and oxygenated blood to the body.將無氧血輸送至肺部以及將含氧血輸送至全身。心臟瓣膜Tricuspid valve三尖瓣——stop the blood flows back to right atrium.阻止血液回流到右心房。Mitral valve兩尖瓣——stop the blood flows back to left atrium.

阻止血液回流到左心房。

Pulmonary valve肺動(dòng)脈瓣——stop the blood flows back to right ventricle.阻止血液回流到右心室。

Aortic valve主動(dòng)脈瓣——stop the blood flows back to left ventricle.

阻止血液回流到左心室。

心臟泵血的過程：Atrial systole(心房收縮)——The atrium contract, this forces the tricuspid and mitral valves open and blood flows into the ventricles.心房收縮，三尖瓣與兩尖瓣打開血液進(jìn)入心室。Ventricular systole(心室收縮)——The contraction of the ventricles makes the tricuspid and mitral valve to close and ?forces the semilunar valve to open, thus this allows blood to leave the left ventricle through the aorta and right ventricle through the pulmonary artery.心室收縮三尖瓣與兩尖瓣因壓力而關(guān)閉阻止血液回流入心室，肺動(dòng)脈瓣與主動(dòng)脈瓣打開血液進(jìn)入肺部以及全身。Cardiac diastole(心臟舒張) ——Atriums and ventricles relax and pressure inside the heart chambers decreases. This causes semilunar valve in the aorta and pulmonary artery close, preventing backflow of blood.心房與心室在完成動(dòng)作后都會(huì)有短暫的舒張，房室內(nèi)壓力下降，肺動(dòng)脈瓣與主動(dòng)脈瓣閉合防止血液回流。?語言應(yīng)用是一門技能Language learning is a skill.理解僅僅是第一步

Understanding is just the beginning.

有效練習(xí)是掌握這門技能的關(guān)鍵

Effective practice makes perfect.