Sexual behavior

Sexual behavior

Mating is a basic but complex phenomenon in which many parts of the nervous system are involved. Copulation it self is made up of a series of reflexes integrated in spinal and lower brain stem centers, but the behavioral components that accompany it, the urge to copulate, and the coordinated sequence of events in the male and female that lead to pregnancy  are regulated to a large degree in the limb system and hypothalamus.Learning plays a part in the development of mating behavior , particularly in primates, but in non primate mammals, courtship and sexual experience. The basis responses are therefore innate and are undoubtedly present in all mammals.However, in humans, the sexual functions have become  extensively encephalitic and conditioned by social and psychic factors.

Relation to endocrine function :In nonprimate mammals, removal of the gonads leads eventually to decreased or absent sexual activity in both the male and the famele-although the loss is slow to develop in the males of some species.Injections of gonadal hormones in castrated animals revive sexual activity.Testosterons in the male and estrogen in the famale have the most marked effect.Large doses of testosterone and other androgens in castrated females initiate female behavior,and large doses of estrogens in castrated malrs trigger male mating responses.It is unsettled why responses appropriate to the sex of the animale occur when the hormones of the opposite sex are injected.In woman,ovariectomy dose not necessarily reduce libido ( defined in this contest as sexual interest and drive ) or sexual ability Postmenopausal pattern.However,adrenal androgens are still present in these women.Testosterone, for example,increases libido in males, and so dose estrogen used to treat diseases such as carcinoma of the prostate. The behavioral pattern that was present before treatment is stimulated but not redirected.Thus, administration of estosterone to homesexuals intensifies their homesexual drive but does not convert it to a heterosexual drive.

Neural control in the female:In mammals, the sexual activity of the female is cyclic.Most of the time, the female avoids the male and repulses his sexual advences. Periodically,however, there is an abrupt change in behavior and the famele seeks out the male , atteempting to mate. These short episodes of heat or estrus are so characteristic that the sexual cycle in mammalian species that do not menstruate species that do not menstruate is named the estrous cycle.In women sexual activity occurs throughout the menstrual cycle.

Neural control in the male : In male animals, removal of the neocortex generally inhibits sexual behavior. However, cats and monkeys with bilateral limbic lesions localized to the piriform cortex overlying the amygdale develop a marked intensification of sexual activity.They not only mount adult females; they also mount immature females and other males and attempt to copulate with animals of other specics and with inanimate objects. The extent to which these animal studies are applicable to men are uncertain though there have been a few reports of hypersexuality in man with bilateral amygdaloid lesions. The hyporthalamus also involved in the control of sexual activity in males.Simulation along the medial forebrain bundle and un neighboring hypothalamic areas causes penile erection with considerable emotional display in monkeys. In castrated rats, intrahypothalamic implants of testosterone restore the complete pattern of sexual behavior.                        

Genetic sex : If the chromosomal pattern is XX, the subject, no matter what  is the outward appearance, is genetically a female. Conversely if the chromosomal pattern is XY, the subject is male ( irrespective of the outer appearance ). Hence XX and XY are female and male genotypes respectively.

Gonadal sex : Testes and ovaries are the male and the female gonads respectively. Therefore, when testes are present, the  subject is gonadally, a male. Similarly, presence of the ovaries means that the subject is gonadally, a female. Psychological sex : Psychological sex is the sex which the individual believes that he or she belongs to. Thus, if a girl from her infancy, is mistaken as a boy and is reared up among the boys and she thinks that she is a boy, her psychological sex is male. In vast majority of cases, there is no confusion in sex characteristics, that is, in a male, the genetic, gonadal, phenotype and the psychological sex are all male; so is the case with the female. Rarely however, anomalous situation arises. Thus, someone may
have a male genotype pattern of sex (XY) and yet the appearances from outwards ( the external genitalia, the dress ) may be of the female type and the subject believes that he is female.

Sex determination : By the term sex determination, is it meant how the genetic sex patterens are made. Sex differentiation means the development of gonads, accessory sex organs and the psychological aspects of sex. Thus, sex determination occurs during the fertilization of the ovum. On the other hand, in the early weeks of intrauterine life,the gonadal and gender sex of the fetus are not differentiated. After a few weeks of intrauterine life, a fetal gonadal and gender sex differentiation ( that is, outward sex differentiating
features like the development of testes, penis, prostate etc. in males or ovary, uterus, vagina, vulva etc. in the female ) occur. Mechanism of sex determination : Human beings have 46 ( 23 pairs of ) chromosome of which 44 are autosomes and the rest two are sex chromosome. These two sex chromosomes in case of the female are XX, wheres in case of male, are XY. Therefore, the
male and the female chromosomal pattern can be written as 44 + XY ( =46 ) and 44 + XX ( =46 ) respectively.Owing to the reduction  cell division (meiosis) a gamet ( a spermatozoon or an unfertilized oveum ) will contain 22 autosomes+ 1 sex chromosme. In case of an oveum it has to be (obviously) always 22+X, or 22+Y. Now during fertilization, one such spermatozoon and one such ovum unite to form a zygote. Therefore from the ovum the zygote is always getting 22+X but from the spermatozoon it may get either 22+
X or 22+Y. When fertilization occurs, therefore, the zygotes chromosomal pattern ( Karyotype ) can be 44+XY, and the genotype of the genetic sex of the zygote will be female (44+XX) or male (44+XY) respectively. Thus the spermatozon (not the ovum) is the sex determining factor.

Clinical determination of the sex in a given person : In some critical situation, it may be necessary ( despite the outward apperance ) to determine the sex of a given individual. For example, a so called women athleteis phenotype may be female but genotype of a male (and thus not eligible to complete in events exclusively ment for the females)