1.71. Menstrual Cycle http://www.ck12.org
1.71 Menstrual Cycle
- Outline the monthly cycle of the female reproductive system.
What happens during the menstrual cycle?
When you think of the menstrual cycle, you probably think of the discharge of blood that happens during menstrua-
tion. This is only one small part of the female monthly cycle, however.
The Female Monthly Cycle
Themenstrual cycleis a series of changes in the reproductive system of mature females that repeats every month.
While the egg and follicle are developing in the ovary, tissues are building up inside theuterus, the reproductive
organ where the baby would develop. The uterus develops a thick lining covered in tiny blood vessels. This prepares
the uterus to receive an egg that could develop into a child.
If a spermdoes notenter an egg, the lining of the uterus breaks down. Blood and other tissues from the lining break
off from the uterus. They pass through the vagina and out of the body. This is calledmenstruation. Menstruation is
also called a menstrual period. It lasts about 4 days, on average. When the menstrual period ends, the cycle repeats.
Some women feel discomfort during this process (Figure1.133).