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Vaginas
In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The vaginal introitus is normally partly covered by a thin layer of mucosal tissue called the hymen. The vagina allows for copulation and birth. It also channels menstrual flow, which occurs in humans and closely related primates as part of the menstrual cycle. To accommodate smoother penetration of the vagina during sexual intercourse or other sexual activity, vaginal moisture increases during sexual arousal in human females and other female mammals. This increase in moisture provides 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 other people can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaginal Opening And Hymen
In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular sex organ, reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The #Vaginal opening and hymen, vaginal introitus is normally partly covered by a thin layer of mucous membrane, mucosal tissue called the hymen. The vagina allows for Copulation (zoology), copulation and birth. It also channels Menstruation (mammal), menstrual flow, which occurs in humans and closely related primates as part of the menstrual cycle. To accommodate smoother penetration of the vagina during sexual intercourse or other sexual activity, vaginal moisture increases during sexual arousal in human females and other female mammals. This increase in moisture provides vaginal lubrication, which reduces friction. The texture of the vaginal walls creates friction for the penis during sexual intercourse and stimulates it toward ejaculation, en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penis
A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate. The term ''penis'' applies to many intromittent organs of vertebrates and invertebrates, but not to all. As an example, the intromittent organ of most Cephalopoda is the hectocotylus, a specialized arm, and male spiders use their pedipalps. Even within the Vertebrata, there are morphological variants with specific terminology, such as Hemipenis, hemipenes. Etymology The word "penis" is taken from the Latin word for "Latin profanity#Synonyms and metaphors, tail". Some derive that from Proto-Indo-European language, Indo-European ''*pesnis'', and the Greek word πέος = "penis" from Indo-European ''*pesos''. Prior to the adoption of the Latin word in English, the penis was referred to as a "yard". The Oxford English Dictionary cites an example of the w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urogenital Sinus
The urogenital sinus is a body part of a human or other Placentalia, placental only present in the development of the urinary system, development of the urinary and development of the reproductive organs, reproductive organs. It is the ventral part of the cloaca, formed after the cloaca (embryology), cloaca separates from the anal canal during the fourth to seventh weeks of development. In males, the UG sinus is divided into three regions: upper, pelvic, and phallic. The upper part gives rise to the urinary bladder and the pelvic part gives rise to the prostatic and membranous parts of the urethra, the prostate and the bulbourethral glands (Cowper's). The phallic portion gives rise to the spongy (bulbar) part of the urethra and the urethral glands (Littré's). In females, the pelvic part of the UG sinus gives rise to the sinovaginal bulbs, structures that will eventually form the inferior two thirds of the vagina. This process begins when the lower tip of the paramesonephric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birth
Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the fetus at a developmental stage when it is ready to feed and breathe. In some species, the offspring is precocial and can move around almost immediately after birth but in others, it is altricial and completely dependent on parenting. In marsupials, the fetus is born at a very immature stage after a short gestation and develops further in its mother's womb Pouch (marsupial), pouch. It is not only mammals that give birth. Some reptiles, amphibians, fish and invertebrates carry their developing young inside them. Some of these are Ovoviviparity, ovoviviparous, with the eggs being hatched inside the mother's body, and others are Viviparity, viviparous, with the embryo developing inside their body, as in the case of mammals. Human childbirth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safe Sex
Safe sex is sexual activity using methods or contraceptive devices (such as condoms) to reduce the risk of transmitting or acquiring sexually transmitted infections (STIs), especially HIV. "Safe sex" is also sometimes referred to as safer sex or protected sex to indicate that some safe sex practices do not eliminate STI risks. It is also sometimes used colloquially to describe methods aimed at preventing pregnancy that may or may not also lower STI risks. The concept of "safe sex" emerged in the 1980s as a response to the global AIDS epidemic, and possibly more specifically to the AIDS crisis in the United States. Promoting safe sex is now one of the main aims of sex education and STI prevention, especially reducing new HIV infections. Safe sex is regarded as a harm reduction strategy aimed at reducing the risk of STI transmission. Although some safe sex practices (like condoms) can also be used as birth control (''contraception''), most forms of contraception do not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexually Transmitted Disease
A sexually transmitted infection (STI), also referred to as a sexually transmitted disease (STD) and the older term venereal disease (VD), is an infection that is spread by sexual activity, especially vaginal intercourse, anal sex, oral sex, or sometimes manual sex. STIs often do not initially cause symptoms, which results in a risk of transmitting them to others. The term ''sexually transmitted infection'' is generally preferred over ''sexually transmitted disease'' or ''venereal disease'', as it includes cases with no symptomatic disease. Symptoms and signs of STIs may include vaginal discharge, penile discharge, ulcers on or around the genitals, and pelvic pain. Some STIs can cause infertility. Bacterial STIs include chlamydia, gonorrhea, and syphilis. Viral STIs include genital warts, genital herpes, and HIV/AIDS. Parasitic STIs include trichomoniasis. Most STIs are treatable and curable; of the most common infections, syphilis, gonorrhea, chlamydia, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilization
Fertilisation or fertilization (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or offspring. While processes such as insemination or pollination, which happen before the fusion of gametes, are also sometimes informally referred to as fertilisation, these are technically separate processes. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms, the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation. History In antiquity, Aristotle conceived the formation of new individuals through fusion of male and female fluids, with form and function emerging gradually, in a mode c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ejaculation
Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the penis through the urethra. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. After forming an erection, many men emit Pre-ejaculate, pre-ejaculatory fluid during stimulation prior to ejaculating. Ejaculation involves involuntary Muscle contraction, contractions of the pelvic floor and is normally linked with orgasm. It is a normal part of male Puberty, human sexual development. Ejaculation can occur spontaneously during sleep (a nocturnal emission or "wet dream") or in rare cases because of prostate, prostatic disease. ''Anejaculation'' is the condition of being unable to ejaculate. ''Painful ejaculation, Dysejaculation'' is an ejaculation that is painful or uncomfortable. Retrograde ejaculation is the backward flow of semen from the urethra into the urinary bladder, bladder. Premature ejaculation happens shortly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaginal Lubrication
Vaginal lubrication is a naturally produced fluid that lubricates the vagina. Vaginal lubrication production increases significantly during sexual arousal in anticipation of sexual intercourse. Vaginal dryness is the condition in which this lubrication is insufficient, and sometimes artificial lubricants are used to augment it. Without sufficient lubrication, sexual intercourse can be painful. The vaginal lining has no glands, and therefore the vagina must rely on other methods of lubrication. Plasma from the vaginal walls due to vascular engorgement is considered to be the chief lubrication source, and the Bartholin's glands, located slightly below and to the left and right of the introitus (vaginal opening), also secrete mucus to augment vaginal wall secretions. Near ovulation, cervical mucus provides additional lubrication. Mechanism Composition Vaginal lubrication fluid is a plasma transudate which diffuses across the vaginal wall. Composition varies with the length of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Arousal
Sexual arousal (also known as sexual excitement) describes the Physiology, physiological and psychological responses in preparation for sexual intercourse or when exposed to Sexual stimulation, sexual stimuli. A number of physiological responses occur in the body and mind as preparation for sexual intercourse, and continue during intercourse. #Male physiological response, Male arousal will lead to an erection, and in #Female physiological response, female arousal, the body's response is engorged sexual tissues such as Erection of nipples, nipples, Clitoral erection, clitoris, Vagina#Microanatomy, vaginal walls, and vaginal lubrication. Stimulus (psychology), Mental stimuli and Stimulus (physiology), physical stimuli such as touch, and the internal fluctuation of hormones, can influence sexual arousal. Sexual arousal has several stages and may not lead to any actual sexual activity beyond a mental arousal and the physiological changes that accompany it. Given sufficient sexual st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
