Using extremely hot hair styling tools such as hair blow, hair iron (some hair straighteners are known as this in Turkey), hair straightener to straighten or style your hair, damages your hair. These styling procedures damage the hair ends, and cause them split, and break.
The broken hair falls out, and yet, straightening your hair cannot damage the hair follicles that look like onion rings, which are in the hair roots. Because the heat of the hair straighteners cannot reach that deep, however, straightening your hair with a very hot tool will cause irritation on your scalp and dry your scalp.
When you use hot styling tools on your hair, your hair will be damaged, and there will be some irritation on your scalp but your hair roots will not be damaged.