What causes a girl to develop into a woman?
Adult female characteristics, such as breasts, develop during the teen years. What causes this to happen? The development of the female traits is caused by the hormones produced by the female reproductive system.
The Female Reproductive System Functions
Most of the male reproductive organs are outside of the body. But female reproductive organs are inside of the body. The male and female organs also look very different and have different jobs. Two of the functions of the female reproductive system are similar to the functions of the male reproductive system. The female system:
- Produces gametes, the reproductive cells, which are called eggs in females.
- Secretes a major sex hormone, estrogen.
One of the main roles of the female reproductive system is to produce eggs. Eggs (Figure below) are female gametes, and they are made in the ovaries. After puberty, females release only one egg at a time. Eggs are actually made in the body before birth, but they do not fully develop until later in life. Like sperm, eggs are produced by meiosis, so they contain half the number of chromosomes as the original cell.
Another role of the female system is to secrete estrogen. Estrogen is the main sex hormone in females. Estrogen has two major roles:
- During the teen years, estrogen causes the reproductive organs to develop. It also causes other female traits to develop. For example, it causes the breasts to grow.
- During adulthood, estrogen is needed for a woman to release eggs. On average, a woman releases one egg each month from her ovaries.
The female reproductive system has another important function. After puberty, the female reproductive system must prepare itself to accept a fertilized egg each cycle (about every month). This cycle is controlled by a well-planned and very complex interplay of hormones. If an egg is not fertilized, the system must prepare itself again the next cycle. The female reproductive system also supports a baby as it develops before birth, and it facilitates the baby's birth at the end of pregnancy.
This represents a human egg, which is the gamete, or reproductive cell, in females. Notice that is does not have a distinct shape, like a sperm cell has. The egg is a round cell with a haploid nucleus in the center. The egg contains most of the cytoplasm and organelles present in the first cell of a new organism.
- The functions of the female reproductive system are to produce eggs, secrete estrogen, and support a baby as it develops before birth.
- Estrogen, the main sex hormone in females, causes the female traits and reproductive organs to develop and is needed for the release of eggs.
Use the resource below to answer the questions that follow.
- Female Reproductive System at http://www.youtube.com/watch?v=SkcddD0LGlM (5:01)
- What hormones are involved in the female reproductive process?
- What are ovaries? What is their function?
- What is an oocyte?
- How many chromosomes are in a human egg cell?
- What is the function of the follicles? Where are they located?
- What is the function of the uterus?
- List the two major roles of estrogen in females.
- What are the main roles of the female reproductive system?