vagina

In mammals, the vagina is a muscular and tubular part of the female genital tract, which, in humans, extends from the vulva to the cervix. The outer vaginal opening may be partly covered by a membrane called the hymen. At the deep end, the cervix (neck of the uterus) bulges into the vagina. The vagina allows for sexual intercourse and childbirth, and chaels menstrual flow, which occurs periodically as part of the menstrual cycle.

The vagina has been studied in humans more than it has been in other animals. Its location and structure varies among species, and may vary in size within the same species. Female mammals usually have the opening of the urethra of the urinary system separate to the vaginal opening of the genital tract. This is different to male mammals, who usually have a single opening, the external urethral opening for both urination and reproduction. The vaginal opening is much larger than the nearby urethral opening, and both are protected by the labia in humans. In amphibians, birds, reptiles and monotremes, the cloaca is the single external opening for the gastrointestinal tract and the urinary and reproductive tracts.

To accommodate smoother penetration of the vagina during sexual intercourse or other sexual activity, vaginal moisture increases during sexual arousal in human females and also in other female mammals. This increase in moisture is vaginal lubrication, which reduces friction. The texture of the vaginal walls creates friction for the penis during sexual intercourse and stimulates it toward ejaculation, enabling fertilization. Along with pleasure and bonding, women's sexual behavior with others (which can include heterosexual or lesbian sexual activity) can result in sexually transmitted infections (STIs), the risk of which can be reduced by recommended safe sex practices. Other disorders may also affect the human vagina.

The vagina and vulva have evoked strong reactions in societies throughout history, including negative perceptions and language, cultural taboos, and their use as symbols for female sexuality, spirituality, or regeneration of life. In common speech, the word vagina is often used to refer to the vulva or to the female genitals in general. By its dictionary and anatomical definitions, however, vagina refers exclusively to the specific internal structure, and understanding the distinction can improve knowledge of the female genitalia and aid in health care communication.

موضوعات مرتبط: اخبار جدیدها