A-Level考试中，生物类型题作为考查的一种，有很多知识点需要考生们记忆，今天小编就为大家介绍A-Level考试生物知识点：动脉粥样硬化。

　　Lifestyle,Health and Risk

　　Risk of cardiovascular disease:Atherosclerosis.

　　Atherosclerosis is the hardening of arteries caused by the build-up of fibrous plaque called an atheroma. Atheroma formation is the cause of many cardiovascular diseases and occurs as following:

　　动脉粥样硬化（atherosclerosis，AS）是冠心病、脑梗死、外周血管病的主要原因。脂质代谢障碍为动脉粥样硬化的病变基础，其特点是受累动脉病变从内膜开始，一般先有脂质和复合糖类积聚、出血及血栓形成，进而纤维组织增生及钙质沉着，并有动脉中层的逐渐蜕变和钙化，导致动脉壁增厚变硬、血管腔狭窄。

　　Atherosclerosis - Step 1 - Damage

　　The first step and so the cause of atherosclerosis is damage to the endothelium of an artery.

　　The endothelium is a very thin layer of cells that lines the inside of an artery and thus is quite vulnerable to damage from the high pressure blood flow that an artery (the blood vessel that carries blood away from the heart) has to deal with.

　　Atherosclerosis - Part 2 - Inflammatory Response

　　After the endothelium has been damaged, an inflammatory response occurs.

　　White blood cells leave the blood vessel and move into the artery wall.

　　Chemicals accumulate on the white blood cells, particularly cholesterol.

　　This deposit is called an atheroma (making up the 'athero' in 'atherosclerosis')

　　Atherosclerosis - Part 3 - Sclerosis

　　Fibrous tissue and calcium salts add themselves to the atheroma formed.

　　This creates a hard plaque (hard swelling of the aterial wall)

　　As a result, elasticity of the artery is lost.

　　Atherosclerosis - Part 4 - Positive Feedback

　　Since the plaques make the artery narrower (by taking up space in the lumen), blood pressure is raised.

　　Higher blood pressure increases the chance of atherosclerosis and therefore as atherosclerosis increases, the chance of acquiring further atherosclerosis increases

　　Atherosclerosis is multi-factorial and has modifiable and non-modifiable risk factors

　　（病因）：

　　1.Genetics遗传因素(genetic predisposition to high blood pressure etc.)

　　2.Age年龄 (arteries become less elastic with age)

　　3.Diet饮食 (diet can increase cholesterol)

　　4.High blood pressure 高血压 (can damage endothelium)

　　5.High cholesterol levels高血脂

　　6.Smoking 吸烟 (nicotine narrows arteries)

　　7.Physical inactivity不运动 (increases obesity risk)

　　8.Obesity肥胖 (increases blood pressure etc.)

　　Thus risk of CDV can be reduced by stopping smoking, regular exercise,

　　reducing consumption of alcohol, dietary changes and maintaining healthy body weight.

　　Preventing Atherosclerosis:

　　预防措施

　　Exercise: Make it a hobby to find some physical activity you enjoy.

　　★ Start slow and work up to 30 minutes of walking daily.

　　★ Take the stairs. Walk up one flight, or down two.

　　★ At the grocery store, park the car at the far end of the lot and walk.

　　★ Take an extra lap around the mall before heading home.

　　Diet: Eating five servings of fruits and vegetables daily is effective at preventing heart disease.

　　Make it a habit to try something different in the produce aisle each time you hit the supermarket.

　　以上就是本文关于A-Level考试生物知识点动脉粥样硬化的介绍了，希望对大家有所帮助。更多alevel学习、alevel评分标准的问题，可咨询留学经验网。