Menstrual Cycle

Menstrual Cycle

The Menstrual Cycle is a natural biological process that occurs in the female reproductive system. It is a monthly cycle that prepares the body for potential pregnancy. The cycle is regulated by hormones such as estrogen and progesterone.

Overview

The menstrual cycle begins with menstruation (bleeding), which usually lasts between three and seven days. This is followed by the follicular phase, where the follicle-stimulating hormone (FSH) stimulates the growth of a follicle in the ovary. The follicle contains an egg and produces estrogen, which thickens the lining of the uterus.

The ovulation phase occurs around the middle of the cycle, when a surge in luteinizing hormone (LH) causes the follicle to release the egg. If the egg is fertilized by a sperm, it can implant in the uterus and develop into a fetus. If the egg is not fertilized, it disintegrates and is shed along with the lining of the uterus during the next menstruation.

Hormonal Regulation

The menstrual cycle is regulated by a complex interplay of hormones. The hypothalamus produces gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to produce FSH and LH. These hormones in turn stimulate the ovaries to produce estrogen and progesterone.

Phases of the Menstrual Cycle

The menstrual cycle can be divided into three phases: the menstrual phase, the proliferative (or follicular) phase, and the secretory (or luteal) phase.

Menstrual Phase

The menstrual phase is the first phase of the menstrual cycle. It begins on the first day of menstruation and lasts until the end of bleeding. During this phase, the lining of the uterus (the endometrium) is shed and expelled from the body.

Proliferative Phase

The proliferative phase follows the menstrual phase. During this phase, the endometrium begins to thicken in preparation for potential implantation of a fertilized egg.

Secretory Phase

The secretory phase is the final phase of the menstrual cycle. During this phase, the endometrium continues to thicken and secrete substances that will nourish a fertilized egg if implantation occurs.

See Also

• Ovulation
• Menstruation
• Hormones
• Reproductive system

Menstrual Cycle Resources
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