Page 90 - 86 human physiology part-2

The Female Reproductive System

Internal Genitals

Vagina

The vagina is a muscular, hollow tube that extends from the vaginal opening to the cervix of the
uterus. It is situated between the urinary bladder and the rectum. It is about three to five inches long in
a grown woman. The muscular wall allows the vagina to expand and contract. The muscular walls are
lined with mucous membranes, which keep it protected and moist. A thin sheet of tissue with one or
more holes in it, called the hymen, partially covers the opening of the vagina. The vagina receives
sperm during sexual intercourse from the penis. The sperm that survive the acidic condition of the
vagina continue on through to the fallopian tubes where fertilization may occur.

The vagina is made up of three layers, an inner mucosal layer, a middle muscularis layer, and an
outer fibrous layer. The inner layer is made of vaginal rugae that stretch and allow penetration to occur.
These also help with stimulation of the penis. The middle layer has glands that secrete an acidic mucus
(pH of around 4.0.) that keeps bacterial growth down. The outer muscular layer is especially important
with delivery of a fetus and placenta.

Purposes of the Vagina

• Receives a males erect penis and semen during sexual intercourse.
• Pathway through a womans body for the baby to take during childbirth.
• Provides the route for the menstrual blood (menses) from the uterus, to leave the body.
• May hold forms of birth control, such as a diaphragm, FemCap, Nuva Ring, or female
condom.

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