Séxualité
During the first month from the initial single cell, resulting from the fusion of two gametes, successive divisions by mitosis forming cells are of two types: peripheral cells will develop into Annexes (placenta, cord …), central cells will form the embryo.
On Day 7, the ICM consists of two types of cells, forming two layers: the ectoderm and the endoderm. The ectoderm will form the skin, nails, tooth enamel, nerve tissue (brain, spinal cord, part of the eye and the pituitary gland) and membranes of the egg. The endoderm gives the digestive glands and the epithelium lining the digestive tract and respiratory tract.
To 13 ° day, the egg measures about 1.5 mm in diameter, has a shape of a sphere. The embryo is a disk of two layers, about 0.15 mm in diameter.
To 22 ° day, the embryo is 2 mm and one guesses the blanks and optical aids. Few embryonic vessels met in networks that merge into a tube: that the draft is bustling heart rhythmic contractions.
To 26 ° day (4 week), the embryo is 4 mm. The upper limbs are growing and the kidneys. A bud announces the liver and gallbladder. The primitive gut is formed. The neural tube, future draft of the nervous system starts up. At the front, the optic cups thus appear that the cells of the olfactory system.
At 32 ° day (1 month), the embryo is 5-7 mm. The lower limbs develop. The heart chambers are widening. Early fetal red blood cells are formed. Thyroid, parathyroid, thymus, stomach, pancreas develop. The trachea appears with two lung buds. Nerves and ganglia are formed. The neural tube develops into the brain before and is primitive. The uterus is the size of a tangerine.
During the 2nd month, the major organs are forming is organogenesis, the modeling is refined in appearance, it morphogenesis.
At 6 weeks, the face is more detailed. Undifferentiated gonads are in place. The four heart chambers are well defined.Lung lobes, spleen, hands, bowel are well differentiated. The brain continues its development and the two hemispheres are formed. The pancreas appears. Many tissue condensations prefigure the future bones. The embryo mesure17 mm.
At 7 weeks, the mouth grows. The kidneys continue to form. The sexual glands are differentiated by sex in testes or ovaries. Fingers and toes are individualized. The 110 bones which form the skeleton in place. Large blood vessels are visible. The bronchi branch out. The first muscles form. The spinal cord is formed. The embryo measures 27 mm.
At 8 weeks, the eyes, eyelids, ears and limb bones are formed. All members cartilaginous pieces are in place. The first points of ossification appear in the vertebrae. The liver and heart are well developed. The tongue is formed from a single blank median. The lips are well separated from the blade teeth. The larynx is well established. The stomach takes its shape and final spot.The rectum is clearly separated from the whole bladder-urethra. The renal tubules are formed. At 51 days of life, the embryo is 28 mm.
At the end of the 2nd month, there is a rotation of members is in the opposite direction to the upper and lower limbs: and be allowed the bending of elbows and knees. The embryo is 3 cm and weighs 11 g.
Pierre Robin syndrome, atresia of the esophagus to create the 4th week. Congenital heart disease are installed during the 5th and the 6th week. The cleft lip is formed during the 7th week as the cleft palate is visible at the end of the 2nd month.
After six months, these phenomena may also occur, theoretically, outside the womb if the woman gives birth prematurely: the fetus is viable said.
During the 3rd month, members become harmonious. The nails are formed. The first hair appeared. The human face is already: the eyes are close together and covered with lids. The palate is well drawn. The vocal cords are formed. The bronchi divide. The liver seems enormous:occupying almost the entire abdomen. The intestine lengthens, curls and enriched nerve plexus which will assure him traction. The definitive kidney in place. The sex of the child may be known. At the end of 3rd month, the fetus is 10 cm and weighs 45 g. He starts to move but her movements, not yet perceived by the mother, are detected as ultrasound. The uterus is the size of a grapefruit.
During month 4, the first hair appear and a fine down on the whole body (lanugo). The skin is very thin and lets see through the blood vessels. The skeleton is ossified. The cardiac activity, which existed since the 1st month, is now audible through ultrasound (140-150 beats / min). Kidney function and fetal urine in the amniotic fluid. The intestine is filled with a greenish-black substance produced in the metabolism of liver meconium. It measures 15 cm and weighs 200 g. The uterus is the size of a coconut. Fundal height is 16 cm. The mother may feel her baby move.
During the 5th month, the blood that had implemented from the 1st month spreads throughout the body and the blood reaches the extremities. The thymus reaches its maturity. The fetus synthesizes its own antibodies. Fingerprints are widening. The first cerebral convolutions are emerging. The fetus swallows every day several liters of amniotic fluid swallowed it. It can be observed on ultrasound respiratory movements of the rib cage. Itself is moving a lot in the amniotic fluid. It weighs 500 grams and measures 25 cm. The uterus was the size of a melon. Fundal height is 20 cm.
During the 6th month, the fetus sucks its thumb. He sleeps 18 to 20 hours a day. When not sleeping, he does not stop fidgeting. His face is almost finished. The furrows of the brain are increased. The bronchial tree is almost finished. It weighs 1100 grams and mesure31 cm. The uterus is the size of a watermelon. Fundal height is 24 cm.
During the 7th month, the child’s body is covered with a protective coating fat: vernix caseosa.The eyes open but the environment in which he bathes is obscure. He hears noises inside (his mother’s heart, voice, intestinal gurgling …) and outside the womb. He began to feel cramped in the womb. This is the month for the development of nerves. The convolutions are becoming more numerous and profound. It weighs 1700 g and measuring 40 cm. It is viable. Fundal height is 28 cm.
During the 8th month, the skin thickens and becomes more pink than red. This is the month of the accumulation of fat. The baby grows to 250 g per week. The fetus and rocking her head up and down. It weighs 2500 grams and measures 45 cm. Uterine size is 30-31 cm. The mother of frequent urination. She quickly ran out of steam and may suffer from sciatica, varicose veins, hemorrhoids, heartburn. Uterine contractions begin to be felt.
During the 9th month, the child is finished. Everything is ready for delivery. Meanwhile, it gains weight: 100 g per week. He weighed 3300 g at term and 50 cm. Uterine size is 32-33 cm.
The fetal blood contains less oxygen than the adult fetal hypoxemia supports this because he lives economically: being warm, it does not need to regulate its temperature is maintained at 37 °, blood pressure is low. Fetal circulation excludes the lung.
In the womb, the fetus drinks the amniotic fluid which is composed of water and wastes from the skin peeling of his skin and digested by the intestine; not equivalent residues continue to accumulate in the colon, forming a pasty liquid, meconium. There is normally no stool in the womb. (Meconium will be issued within twenty-four hours of life).
The development of central nervous system begins early and continues throughout fetal life and during the first years of life outside the womb. The proliferation of neurons occurs early and ends around the 20 ° week. Then, the connections between neurons multiplent cell for a few years. Glial cells are multiplent until the age of 2 years.Myelination of neurons starts from the 30th week and continues until about age 4. The rapid increase in brain weight is seen in the second half of pregnancy and during the first two years of extra-uterine life is these phenomena.
The fetus hears sounds abdominal maternal heartbeat, and especially the voice of his mother, he doubtless heard the sounds outside when they are powerful enough or close enough and can make him listen to music. The sounds it receives, however distorted, not so much by the thickness of the abdominal wall by the presence of amniotic fluid that bathes it.
Finally, it moves in a very large cavity for him at the beginning and then it grows faster than the uterus and ends up cramped. The range of motion in late pregnancy is reduced. He certainly sees the contractions felt that his mother in late pregnancy.
Forum Health Forum Psychology Forum Nutrition
Expressing his desire, fantasies, desires, feel better and share his pleasure, the flame in the couple … Tips to live their sexuality.
Philosophical and psychological journey to the heart of the books …
There was once a girl who fell in love every week. Who had married. And wham. She singled …
33 years, 3 children, divorced. Leaves Paris.
Psychologies Magazine
in January
Visit Summary
Psychologies Magazine
in January
Visit Summary
The term encompasses the phenomena of sexual reproduction biological organisms, sexual reproduction allows this, and finally the many cultural phenomena related to these sexual behaviors.
The sexual division of sexes complementary organizations allows mixing of genes (by meiosis and fertilization) that promotes genetic diversity and adaptation of organisms to their environment.
In humans (and the chimpanzee, the bonobo, the orang utan and the Dauphin, among others), sexual behavior is no longer a breeding behavior, but becomes an erotic behavior. During evolution, the importance and influence of hormones and pheromones on sexual behavior has decreased. Instead, the importance of rewards / reinforcements became major.
Human sexuality depends on the ages and cultures. Differences are observed in the diversity of erotic practices, but especially in the vast diversity of customs, beliefs, values, and sexual depictions. These observations show the ethnological importance of culture in sexual development and expression of human sexuality.
Studies of the feeling of love in Neuroscience suggests a relationship with addiction, a condition which would be caused by endorphins released during relationships. The state of love can cause intense emotions, euphoria or distress.The passions associated with love can be a source of individual or social problems, but also remarkable artistic productions.
Psychobiology of sexual behavior
Sexual behavior
Sexual behavior is the set of motor activities that allow sexual reproduction in animals.
This behavior is mainly controlled by the nervous system but also, especially among the simplest animals, the endocrine system. Schematically, the nervous system is more simple, more sexual behavior is stereotyped. This applies, for example insects. Instead, the nervous system is more complex, more sexual behavior will be developed and linked to cultural phenomena. This is the typical case of human beings.
In mammals, the major biological factors that control sexual behavior are hormones, pheromones, reward and cognition. Because of the differences between species, brain structure is different and the importance of these factors changes.For example, in mice, where the brain is relatively small, hormones are the main factor, whereas in humans, which has a highly developed neocortex, cognition becomes a major factor. In addition, due partly random nature of evolution, organisms and the control of sexual behavior are not ‘optimized’. It is this characteristic that explains the existence of non-reproductive sexual activities.
The article presents detailed sexual behavior: 1) descriptions of the sexual behavior of different animal species, 2) biological factors that control these behaviors, and 3) changes in these biological factors in evolution, so good understand differences in behavior between species.
In mammals, due to changes in the evolution of brain organization, sexual behavior is a reproductive behavior in mammals the simplest, and becomes an erotic behavior in hominids.
Reproductive behavior
Reproductive behavior is sexual behavior typical of lower mammals (rodents, canines, sheep …).
The purpose of this behavior is heterosexual copulation, which allows fertilization and reproduction. Innate factors, mainly hormones, pheromones and sexual reflexes, control this behavior. At puberty, hormones activate reproductive behavior, pheromones trigger sexual arousal and can recognize the opposite sex, and finally sexual reflexes, when the male mounts the female, allow copulation and ejaculation .
The article presents detailed reproductive behavior: 1) the innate and acquired factors causing the behavior, 2) describes the interaction between these factors, and 3) explains the consequences of reproductive behavior modification or a disappearance of these factors during evolution.
Erotic behavior
Erotic behavior is typical sexual behavior of humans and bonobos, dolphins, chimpanzees and orang utan (see top of page cited).
During evolution, the importance and influence of hormones and pheromones on sexual behavior has decreased. Instead, the importance of reward / reinforcement has become major. In humans, the purpose of sexual behavior is more vaginal intercourse but the search for erotic pleasure, obtained by stimulating the body and erogenous zones.
Note that erotic behavior does not develop independently. The affective and cognitive factors, especially the cultural context, have a major influence on its development. Nevertheless, the innate characteristics of this behavior (erogenous zones erotic pleasure …) exist and express themselves regardless of cultural environment.
The article presents detailed erotic behavior:1) biological factors that control this behavior, 2) the development of this behavior, and 3) the characteristics of the cultural environment that affect the development of erotic behavior.
From observations made in human ethology, we note that in all cultures always erotic behavior is organized around the stimulation of the body and erogenous zones. But according to a company, body parts, shapes and means of erotic stimulation change: the genital area is still stimulated, oral and anal areas less frequently. The means of stimulating the genitals can be hand or, less commonly the mouth, tongue or something, sometimes, several or all sensory modalities are stimulated, as in the orgies. Activity duration is also variable. Finally, the erotic activities can be performed alone or with multiple partners, and be heterosexual, homosexual or bisexual, even with animals.Specifically, changes in the behavior exerted by erotic actions on the adults (by fear of sanctions often copies: stoning, stake, hanging, imprisonment … or positively, by social recognition, sexual behavior to reward socially valued ), but mostly on children and adolescents, through aversive conditioning (physical punishment or psychological) or appetitive (rewards, praise …) inductions of negative emotions (fear, shame, disgust …) or positive ( pride …) information reflecting social beliefs (‘masturbation causes disease’ …) and also by the practice of erotic activities culturally accepted. Indirectly, observation, imitation and social learning also play a major role in changing the erotic behavior to culturally accepted practices.
The human sexual behavior related article presents the wide variety of erotic activities:1) in history, 2) in contemporary societies, and 3) the characteristics of the cultural environment that affect the development of behavior.
Sexual reproduction
Sexual reproduction is a mode of reproduction that involves sex complementary organizations. This mode of reproduction is characterized by a life cycle alternating haploid and diploid. The chromosome pairs are separated parents during the formation of gametes (meiosis) and then recombined into a single new body during fertilization. This genetic mixing leads to the species level genetic diversity, thus multiplying the possibilities for adaptation to the environment.
In the vegetable kingdom, is for example the case of angiosperms, most commonly plants flower, the flower is the sexual organ of plants.
In the animal kingdom that genetic mixing is associated with behavioral strategies including selection criteria of various functions.
The article detailed Sexuality (reproduction) shows the different forms of sexual reproduction, describes the mechanisms of genetic exchange, and explains the biological significance of sexual reproduction.
Development of sexuality
Sexuality from childhood to adulthood
The development of sexuality, from embryo to adulthood, is caused by specific biological factors, the following chronological stages and the influence of culture is crucial.
The innate factors of erotic behavior (sexual reflexes, erogenous zones, rewards / reinforcement …) develop from the fetal period and first years of life. Potentially, the body is ready to teach sexuality. Sexual development will be determined later by the cultural context which, from a variable age in societies, or add value to prohibit particular activities erotic, transmit specific sexual beliefs, shaping attitudes, perceptions and sexual values adults.During its development, the child incorporates the gender norms of her society, and in adulthood these standards will be perceived as ‘natural’ and ‘obvious.’
The detailed article Infantile sexuality, according to data from neuroscience and developmental psychology, has: 1) the chronology of development of innate and acquired factors of sexuality, 2) cultural characteristics that influence the development of sexuality, and 3) the main options for changes in the development of sexuality.
The Sexuality related article presents the development of infantile sexuality of the child according to psychoanalytic theory.
Sex education
Sex education in its broadest sense, is inseparable from the development of sexuality. That institutional or informal learning, determined and organized, or left to chance circumstances of life, they determine the fate of most of human sexuality.
In modern societies, issues of sex education are many:access to sexual health, prevention of sexual disorders, learning of knowledge about reproduction, sexuality, pleasure and love, development of sexual socialization, and the moral sense and ethics. But sexuality is a topic in modern societies, and the sexual transmission of knowledge is complicated by a strong social reluctance to sex education and the civil status of minority students. Yet adolescence in the West is a particularly sensitive period of development, and lack of reliable information and lack of communication with trusted adults are handicaps to deal with problems of representation of his body, of sexual identity , beliefs in many stereotypes, sexual performance, sexual relationship to another and the management of emotions and sexual love.
The article presents detailed sex education: 1) educational issues, medical but also social, sexual education, 2) an analysis of the practices of sex education in the twentiethcentury, and 3) the major individual and social benefits of sex education, observed in some countries, particularly in the northern end of the twentieth century.
Definition of sexuality
Etymologically, the word sexuality, sexual and gender are derivatives of Latin words and sexus Sexualis. These words are used in the sixteenth century. The Latin root sexus means ‘separation, distinction.’ The meaning ‘separation’ of the word corresponds to the sexus biological separation of the sexes, which is the fundamental characteristic of sexual reproduction.
Sexual diseases and therapies
At different times, manners and knowledge available, several models have existed for normality physiological, behavioral and psychological. These models determine the abnormal and the pathological: for example, in the ancient model of masculinity, passivity was a crime, while in the nineteenth century, the medical model of the sexual instinct, sexual activities nonbreeding ( masturbation, fellatio, sodomy …) were a perversion.Currently, the main sexual problems are identified sexual dysfunction, paraphilias, and disorders of gender identity. The main diseases related to sexuality are sexually transmitted. In clinical sexology, the treatment methods most commonly used are cognitive and behavioral therapies, methods of Masters and Johnson (sensate focus), the couples therapy, and the sexocorporelle and psychoanalysis.
‘