Tooth extraction for braces is necessary?

M24, as my teeth is crooked, I visited dentist to go with the option of braces to make it aligned. After looking at my x-ray he asked to extract 4 tooth from mouth, Two in upper and Two in lower. Feeling scary about removing the good tooth.Anyone have done braces with extracting the tooth? Will it affect our body? My mom is having little fear about removing the upper tooth she says it will affect the brain nerve and things. Pls help me guys , Is it okay to extract tooth or getting any second opinion from different doctor?