Question

Why do we (girls) have menstrual cycles??

Answer 1

Answer:

Girls have menstrual cycles because girls have changes of hormones in their body. The hormones make  the lining of the uterus  build up. This gets the uterus ready for an egg which when the egg is released it causes a period also known as a menstrual cycle which happens normally every month for at least 3-7 days.

Explanation:

Answer 2

Girls have menstrual cycles as a result of hormonal changes in the body.

What are Hormones?

Hormones are chemical messengers which are secreted directly into  the

blood and involved in the regulation of biochemical activities in the body.

Menstrual cycles occurs due to hormonal changes in the body of

females. Hormones line the uterus in preparation for a fertilized egg but

in cases where fertilization doesn't occur , the egg disintegrates and the

uterine lining is shed. This normally happens every month for at least 3-7

days.

Read more about Hormones here brainly.com/question/11979378