Unit 2 Improving Yourself 课外拓展 脱发介绍 课件-2022-2023学年高中英语外研版（2019）选择性必修第二册

Alopecia 1 2 3 Definition of alopecia Causes and hazards of hair loss How to improve hair loss？ contents 1 What is hair loss？ Definition of alopecia Abnormal hair loss is called alopecia. Healthy people will lose 50-100 hairs every day, because the growth of hair is periodic（间歇的，周期的）, the hair in the growth period will not fall off easily, and the hair in the rest period is in a state of easy fall off. If it is found that the number of hair shedding exceeds 100 or more every day, or the total amount of hair is significantly reduced than before, or it is found that there is obvious thinning of local hair, or even patches formed by complete hair shedding, this is abnormal hair loss. 2 Causes and hazards of hair loss 1 What are the causes of hair loss？ 1.Physiological（生理的） alopecia: The so-called physiological alopecia means that no more than 70-100 hairs fall off every day, a certain amount of hair falls off every day, and a certain amount of hair grows. Although there is alopecia, the hair is not sparse（稀少的）, which is a kind of physiological alopecia. 2.Pathological （病理的)alopecia: First, androgenic(雄性激素的） alopecia. On the basis of heredity（遗传）, androgenic alopecia is a type of alopecia caused by the scalp（头皮） being too sensitive to androgens, which can occur in both men and women, mostly men;Second, alopecia areata, the cause of which is unknown at present, but studies have found that it is mainly related to autoimmunity, including emotional and other stress reactions 3.Resting period hair loss: It is due to some mental factors such as weight loss or disease, especially staying up late to smoke, that many hairs enter the resting period in advance 2 What are the causes of hair loss？ 1 What are the effects of hair loss？ 1.The main harm of hair loss is that it affects the beauty, social interaction, study and work of patients. 2.Hair loss narrows interpersonal relationships. Because of the image problem, alopecia people are often stuck in their laurels. Their breakthr