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11.71: Menstrual Cycle

Difficulty Level: At Grade Created by: CK-12
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What happens during the menstrual cycle?

When you think of the menstrual cycle, you probably think of the discharge of blood that happens during menstruation. This is only one small part of the female monthly cycle, however.

The Female Monthly Cycle

The menstrual cycle is 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 the uterus , 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 sperm does not enter 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 called menstruation . 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 ( Figure below ).

Some people think that the average length of a menstrual period is the same as the “normal” length. They assume that shorter or longer menstrual periods are not normal. In fact, menstrual periods can vary from 1 to 8 days in length. This is usually normal.

The average length of the cycle (time between menstrual periods) is about 28 days, but there is no “normal” cycle length.

Some women experience cramping and pain before and during menstruation.

Vocabulary

  • menstrual cycle : Series of changes in the reproductive system of mature females that repeats every month.
  • menstruation : Process in which blood and other tissues from the lining of the uterus are shed and exit the body.
  • uterus : Female reproductive organ where the baby develops until birth.

Summary

  • The menstrual cycle is a monthly cycle of changes in the ovaries and uterus.
  • During menstruation, blood and other tissues from the lining of the uterus are shed and exit the body.

Practice

Use the resource below to answer the questions that follow.

  1. What is ovulation?
  2. What role does the pituitary gland play in menstruation? What controls the pituitary gland? What does this gland secrete?
  3. How do the ovaries respond to a signal from the pituitary gland?
  4. What does a peak in LH signal?
  5. What role does progesterone play in the menstrual cycle? Where does the progesterone come from?

Review

  1. What happens in the uterus as the egg and follicle are developing in the ovary?
  2. Explain what happens during menstruation.

Vocabulary

menstrual cycle

menstrual cycle

Series of changes in the reproductive system of mature females that repeats every month.
menstruation

menstruation

Process in which blood and other tissues from the lining of the uterus are shed and exit the body.
uterus

uterus

Female reproductive organ where the baby develops until birth.

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Description

Difficulty Level:

At Grade

Grades:

7 , 8

Date Created:

Nov 29, 2012

Last Modified:

Dec 17, 2014
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