The Menstrual Cycle

And the Reproductive System

Created by Mrs. Jane ZiembaPerryville Middle School

What should we understand before we begin?

* It is regulated by a number of hormones.* It’s significant event is ovulation.

* It’s function is to prepare the uterus for the implantation of the fertilized ovum.

* The cycle is interrupted when either pregnancy or menopause occur.

* A girl’s first menstrual cycle is a definite step in her development towards maturation.

Menstrual cycle: starts at puberty and continues until menopause; it’s purpose is to prepare the wall of the uterus for the implantation of the ovum if it has been fertilized

The menstrual cycle is an important event in every girl’s life

It is a physiological change that usually occurs between the ages of 10 and 15

It involves the actions of 4 basic hormones:

* Follicle stimulating hormone

* Luteinizing hormone

* Estrogen

* Progesterone

It prepares the body for reproduction.

Reproduction: the process of conceiving and bearing children

Hormones: special chemicals secreted by endocrine glands that cause changes in specific areas of the body

An average of 28 days is needed to complete each menstrual cycle

The menstrual cycle is considered to start when the bloody discharge first begins to flow from the vagina

The pituitary gland secretes the follicle stimulating hormone into the blood stream.

This causes a follicle inside the ovaries to produce a mature egg.

There are 1000’s of follicles within each ovary, each one containing an immature ovum.

**Pituitary gland: an endocrine gland attached to the base of the brain, which secretes hormones

*Follicle Stimulating Hormone (F.S.H.): a pituitary hormone that stimulates development of ovarian follicles

Estrogen: female sex hormone produced by the ovaries

Estrogen stimulates the lining of the uterus to thicken in preparation for the implantation of a fertilized ovum.

Usually, only ONE follicle is activated at one time, so only ONE egg ripens each month.

When this occurs, the follicle grows larger and begins to secrete estrogen.

* The follicle grows larger and begins to secrete estrogen, often referred to as the “female hormone”

Now the pituitary gland secretes the third hormone, the Luteinizing Hormone

Luteinizing Hormone: pituitary hormone that stimulates estrogen secretion and causes ovulation

Ovulation: the process in which a mature egg is released from the follicle about half-way between the beginning of two successive menstrual periods

Ovulation takes place on about the 14th day of the menstrual cycle.

Ovulation is the time of the month when a female is most likely to become pregnant.

The ripened egg leaves the ovary and is grabbed by the end of the fallopian tube.

The ripened egg is surrounded by feeder cells that nourish it for about two days.

By this time the egg (ovum) is about halfway through the Fallopian tube.

After this time the egg starts to deteriorate

Now into the second half of the cycle, the follicle secretes the final hormone Progesterone.

If the egg is fertilized, progesterone will keep the uterine lining (endometrium) thick and the menstrual cycle will stop.

Progesterone: hormone produced by the ovaries that helps prepare the uterus for a possible pregnancy.

(This is one of the first ways a woman knows she is pregnant: she does not get her period)

What if the egg is not fertilized?If fertilization does NOT occur, the progesterone and estrogen is decreased.

This causes the soft, spongy uterine lining to be shed along with 100’s of tiny blood vessels that are in it.

The appearance of this discharge marks the beginning of a new menstrual cycle.

(This is how a woman who is sexually active knows she is NOT pregnant)

The lining and tissues detach and pass slowly out of the body through the vagina.

Thus, menstruation, begins.

Menstruation: the monthly discharge of blood and cells from the lining of the uterus.

Sometimes, a woman can “sense” that her menstural period is arriving soon.

Many times, PMS symptoms precede the start of menstruation

PMS: (Premenstrual Syndrome)- symptoms such as anxiety, tension, breast tenderness, and bloating which begin several days prior to the onset of menstruation, and subside when menstruation begins.

So how long does the menstrual cycle continue?

The menstrual discharge (often called the period):

* Normally lasts from 3 to 5 days* The entire cycle repeats itself every 22 to 35 days

The menstrual cycle continues on a regular basis until a woman nears the age of 50Menopause: at around age 50, the menstrual cycle

becomes irregular and finally stops altogether.

So, as you can see, the menstrual cycle is a very normal and routine process that gets a woman ready to carry a new life within her .

How would you answer these questions?

1. How is the menstrual cycle started and controlled?

2. Is a girl able to become a mother before her first menstrual period?

3. What is the most important thing that happens during the menstrual cycle?4. What is ovulation and why is it important?