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Obstetrics & Gynecology

The Department of Obstetrics and Gynecology at the Medical College of Georgia at Augusta University is a comprehensive clinical service and educational department, specializing in the healthcare of women both on a primary and referral basis. We provide quality clinical services in following areas: General Obstetrics and Gynecology, Gynecologic Oncology, Maternal-Fetal Medicine, Reproductive Endocrinology, Infertility, and Genetics, and Urogynecology and Pelvic Surgery.

General Obstetrics and Gynecology provides a full range of general obstetrical and gynecological services ranging from outpatient care to surgery, and from routine visits to complicated consultations. In addition to normal obstetrical and gynecological services, our specialized research and interest areas include urodynamics, dysmenorrhea, menorrhagia, pelvic pain, menopause, and others.

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Obstetrics & Gynecology

History of neuroscience – Wikipedia

From the ancient Egyptian mummifications to 18th century scientific research on "globules" and neurons, there is evidence of neuroscience practice throughout the early periods of history. The early civilizations lacked adequate means to obtain knowledge about the human brain. Their assumptions about the inner workings of the mind, therefore, were not accurate. Early views on the function of the brain regarded it to be a form of "cranial stuffing" of sorts. In ancient Egypt, from the late Middle Kingdom onwards, in preparation for mummification, the brain was regularly removed, for it was the heart that was assumed to be the seat of intelligence. According to Herodotus, during the first step of mummification: "The most perfect practice is to extract as much of the brain as possible with an iron hook, and what the hook cannot reach is mixed with drugs." Over the next five thousand years, this view came to be reversed; the brain is now known to be the seat of intelligence, although colloquial variations of the former remain as in "memorizing something by heart".

The Edwin Smith Surgical Papyrus, written in the 17th century BC, contains the earliest recorded reference to the brain. The hieroglyph for brain, occurring eight times in this papyrus, describes the symptoms, diagnosis, and prognosis of two patients, wounded in the head, who had compound fractures of the skull. The assessments of the author (a battlefield surgeon) of the papyrus allude to ancient Egyptians having a vague recognition of the effects of head trauma. While the symptoms are well written and detailed, the absence of a medical precedent is apparent. The author of the passage notes "the pulsations of the exposed brain" and compared the surface of the brain to the rippling surface of copper slag (which indeed has a gyral-sulcal pattern). The laterality of injury was related to the laterality of symptom, and both aphasia ("he speaks not to thee") and seizures ("he shutters exceedingly") after head injury were described. Observations by ancient civilizations of the human brain suggest only a relative understanding of the basic mechanics and the importance of cranial security. Furthermore, considering the general consensus of medical practice pertaining to human anatomy was based on myths and superstition, the thoughts of the battlefield surgeon appear to be empirical and based on logical deduction and simple observation.[1][2]

During the second half of the first millennium BC, the Ancient Greeks developed differing views on the function of the brain. However, due to the fact that Hippocratic doctors did not practice dissection, because the human body was considered sacred, Greek views of brain function were generally uninformed by anatomical study. It is said that it was the Pythagorean Alcmaeon of Croton (6th and 5th centuries BC) who first considered the brain to be the place where the mind was located. According to ancient authorities, "he believed the seat of sensations is in the brain. This contains the governing faculty. All the senses are connected in some way with the brain; consequently they are incapable of action if the brain is disturbed...the power of the brain to synthesize sensations makes it also the seat of thought: The storing up of perceptions gives memory and belief and when these are stabilized you get knowledge."[2] In the 4th century BC Hippocrates, believed the brain to be the seat of intelligence (based, among others before him, on Alcmaeon's work). During the 4th century BC Aristotle thought that, while the heart was the seat of intelligence, the brain was a cooling mechanism for the blood. He reasoned that humans are more rational than the beasts because, among other reasons, they have a larger brain to cool their hot-bloodedness.[3]

In contrast to Greek thought regarding the sanctity of the human body, the Egyptians had been embalming their dead for centuries, and went about the systematic study of the human body. During the Hellenistic period, Herophilus of Chalcedon (c.335/330280/250 BC) and Erasistratus of Ceos (c. 300240 BC) made fundamental contributions not only to brain and nervous systems' anatomy and physiology, but to many other fields of the bio-sciences. Herophilus not only distinguished the cerebrum and the cerebellum, but provided the first clear description of the ventricles. Erasistratus used practical application by experimenting on the living brain. Their works are now mostly lost, and we know about their achievements due mostly to secondary sources. Some of their discoveries had to be re-discovered a millennium after their death.[2]

During the Roman Empire, the Greek anatomist Galen dissected the brains of sheep, monkeys, dogs, swine, among other non-human mammals. He concluded that, as the cerebellum was denser than the brain, it must control the muscles, while as the cerebrum was soft, it must be where the senses were processed. Galen further theorized that the brain functioned by movement of animal spirits through the ventricles. "Further, his studies of the cranial nerves and spinal cord were outstanding. He noted that specific spinal nerves controlled specific muscles, and had the idea of the reciprocal action of muscles. For the next advance in understanding spinal function we must await Bell and Magendie in the 19th Century."[2][3]

Andreas Vesalius noted many structural characteristics of both the brain and general nervous system during his dissections of human cadavers.[4] In addition to recording many anatomical features such as the putamen and corpus collusum, Vesalius proposed that the brain was made up of seven pairs of 'brain nerves', each with a specialized function. Other scientists including Leonardo da Vinci furthered Vesalius' work by adding their own detailed sketches of the human brain. Ren Descartes also studied the physiology of the brain, proposing the theory of dualism to tackle the issue of the brain's relation to the mind. He suggested that the pineal gland was where the mind interacted with the body after recording the brain mechanisms responsible for circulating cerebrospinal fluid.[5]Thomas Willis studied the brain, nerves, and behavior to develop neurologic treatments. He described in great detail the structure of the brainstem, the cerebellum, the ventricles, and the cerebral hemispheres.

The role of electricity in nerves was first observed in dissected frogs by Luigi Galvani in the second half of the 18th century. In the 1820s, Jean Pierre Flourens pioneered the experimental method of carrying out localized lesions of the brain in animals describing their effects on motricity, sensibility and behavior. Richard Caton presented his findings in 1875 about electrical phenomena of the cerebral hemispheres of rabbits and monkeys. Studies of the brain became more sophisticated after the invention of the microscope and the development of a staining procedure by Camillo Golgi during the late 1890s that used a silver chromate salt to reveal the intricate structures of single neurons. His technique was used by Santiago Ramn y Cajal and led to the formation of the neuron doctrine, the hypothesis that the functional unit of the brain is the neuron. Golgi and Ramn y Cajal shared the Nobel Prize in Physiology or Medicine in 1906 for their extensive observations, descriptions and categorizations of neurons throughout the brain. The hypotheses of the neuron doctrine were supported by experiments following Galvani's pioneering work in the electrical excitability of muscles and neurons. In the late 19th century, Emil du Bois-Reymond, Johannes Peter Mller, and Hermann von Helmholtz showed neurons were electrically excitable and that their activity predictably affected the electrical state of adjacent neurons.

In parallel with this research, work with brain-damaged patients by Paul Broca suggested that certain regions of the brain were responsible for certain functions.[6]

Neuroscience during the twentieth century began to be recognized as a distinct unified academic discipline, rather than studies of the nervous system being a factor of science belonging to a variety of disciplines.

Broca's hypothesis was supported by observations of epileptic patients conducted by John Hughlings Jackson, who correctly deduced the organization of motor cortex by watching the progression of seizures through the body. Carl Wernicke further developed the theory of the specialization of specific brain structures in language comprehension and production. Modern research still uses the Korbinian Brodmann's cytoarchitectonic (referring to study of cell structure) anatomical definitions from this era in continuing to show that distinct areas of the cortex are activated in the execution of specific tasks.[6]Eric Kandel and collaborators have cited David Rioch, Francis O. Schmitt, and Stephen Kuffler as having played critical roles in establishing the field.[7] Rioch originated the integration of basic anatomical and physiological research with clinical psychiatry at the Walter Reed Army Institute of Research, starting in the 1950s. During the same period, Schmitt established a neuroscience research program within the Biology Department at the Massachusetts Institute of Technology, bringing together biology, chemistry, physics, and mathematics. The first freestanding neuroscience department (then called Psychobiology) was founded in 1964 at the University of California, Irvine by James L. McGaugh. Kuffler started the Department of Neuroscience at Harvard Medical School in 1966.

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History of neuroscience - Wikipedia

Biochemistry

Welcome to the home page of one of the fastest growing departments of biochemistry in the U.S., where our faculty have developed superb educational and research programs. Learn more about our department.

Charles Brenner, PhD Chair and DEO, Department of Biochemistry

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Biochemistry

ST genetics

Females calving heifers in their first two pregnancies produce up to 981 lbs. more milk over the two lactations than females calving back-to-back males.

(Hinde K, et al, (2014), Holsteins Favor Heifers, Not Bulls: Biased Milk Production Programmed during Pregnancy as a Function of Fetal Sex. PLoS ONE 9(2): e86169. doi:10.1371/journal.pone.0086169)

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ST genetics

Genetics – Advocate Health Care

The Division of Genetics at Advocate Medical Group offers a team of genetic specialists to help individuals and families navigate the complex arena of genetics and genomics. We are committed to the diagnosis, management, and treatment of patients with genetic disorders.

Our specially trained clinical geneticists and genetic counselors provide a full range of services including:

We guide families facing hereditary and genetic disorders through complicated genetic issues in an easy-to-understand manner and provide educational resources helpful to your understanding of a genetic disorder. Our specialists can also help you identify support groups and social services, and coordinate and refer you to appropriate specialty providers based on your diagnosis.

The Division of Genetics offers comprehensive care that extends beyond genetic counseling and diagnosis. Our patients have access to multidisciplinary clinics that offer exceptional, compassionate care to children and adults with a variety of genetic disorders. Individuals in these multidisciplinary clinics have the opportunity to be evaluated by an experienced treatment team which includes multiple specialists from different healthcare disciplines.

Our specialists will determine which genetic tests are most appropriate for your particular situation. We discuss the risks, benefits, and limitations of genetic testing, as well as the emotional issues of a diagnosis and knowing your risk.

The Advocate Medical Group Genetics offers a range of services.

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Genetics - Advocate Health Care

Neuroscience Care at OhioHealth | Columbus Neurology and …

Multiple Sclerosis

At OhioHealth, patients with multiple sclerosis (MS) have access to personalized care all in one place by an interdisciplinary team of specialists who, together, provide comprehensive care throughout the course of their disease. From our MS Clinic to our weekly lectures and support groups, we help MS patients manage their unique symptoms and needs.

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Neuroscience Care at OhioHealth | Columbus Neurology and ...

Eye Specialists of Mid-Florida, P.A.

Education:

Bachelor of Science

Ashland College Ashland, OH 1970

Doctor of Medicine

University of Florida Gainesville, FL 1976

Doctor of Philosophy (Biochemistry)

University of Florida Gainesville, FL 1976

Internship

University of Florida Gainesville, FL 6/76 6/77

Ophthalmology Residency

University of Florida

Gainesville, FL 6/77 6/80

Specialties:

Cataract & Laser Surgery

Locations:

Winter Haven, FL

Sebring, FL

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Eye Specialists of Mid-Florida, P.A.

Department of Cell Biology

Inhibitory synapses act as the brakes in the brain, preventing it from becoming overexcited. Researchers thought they were less sophisticated than their excitatory counterparts because relatively few proteins were known to exist at these structures. But a new study by the Soderling Lab, published Sept. 9 in Science, overturns that assumption, uncovering 140 proteins that have never been mapped to inhibitory synapses. Its like these proteins were locked away in a safe for over 50 years, and we believe that our study has cracked open the safe, said the studys senior investigator Scott Soderling, an Associate Professor of Cell Biology and Neurobiology at Duke. And theres a lot of gems. In particular, 27 of these proteins have already been implicated by genome-wide association studies as having a role in autism, intellectual disability and epilepsy, Soderling said, suggesting that their mechanisms at the synapse could provide new avenues to the understanding and treatment of these disorders. You can read more about this research on Duke Today.

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Department of Cell Biology

Instinct – Wikipedia

Instinct or innate behavior is the inherent inclination of a living organism towards a particular complex behavior. The simplest example of an instinctive behavior is a fixed action pattern (FAP), in which a very short to medium length sequence of actions, without variation, are carried out in response to a clearly defined stimulus.

Any behavior is instinctive if it is performed without being based upon prior experience (that is, in the absence of learning), and is therefore an expression of innate biological factors. Sea turtles, newly hatched on a beach, will automatically move toward the ocean. A kangaroo climbs into its mother's pouch upon being born. Honeybees communicate by dancing in the direction of a food source without formal instruction. Other examples include animal fighting, animal courtship behavior, internal escape functions, and the building of nests.

Instincts are inborn complex patterns of behavior that exist in most members of the species, and should be distinguished from reflexes, which are simple responses of an organism to a specific stimulus, such as the contraction of the pupil in response to bright light or the spasmodic movement of the lower leg when the knee is tapped. The absence of volitional capacity must not be confused with an inability to modify fixed action patterns. For example, people may be able to modify a stimulated fixed action pattern by consciously recognizing the point of its activation and simply stop doing it, whereas animals without a sufficiently strong volitional capacity may not be able to disengage from their fixed action patterns, once activated.[1]

The role of instincts in determining the behavior of animals varies from species to species. The more complex the neural system of an animal, the greater is the role of the cerebral cortex and social learning, and instincts play a lesser role. A comparison between a crocodile and an elephant illustrates how mammals for example are heavily dependent on social learning. Lionesses and chimpanzees raised in zoos away from their birth mothers most often reject their own offspring because they have not been taught the skills of mothering.[citation needed] Such is not the case with simpler species such as reptiles.

In everyday speech, the word instinct is often used to refer to intuition or even clairvoyance.

Jean Henri Fabre, an entomologist, considered instinct to be any behavior which did not require cognition or consciousness to perform. Fabre's inspiration was his intense study of insects, some of whose behaviors he wrongly considered fixed and not subject to environmental influence.[2]

Instinct as a concept fell out of favor in the 1920s with the rise of behaviorism and such thinkers as B. F. Skinner, which held that most significant behavior is learned. These beliefs, like Fabre's belief that most behaviors were simply reflexive, also proved to be too simplistic to account for the complex emotional and social behavior of human beings.

An interest in innate behaviors arose again in the 1950s with Konrad Lorenz and Nikolaas Tinbergen, who made the distinction between instinct and learned behaviors. Our modern understanding of instinctual behavior in animals owes much to their work. For instance, there exists a sensitive period for a bird in which it learns the identity of its mother. Konrad Lorenz famously had a goose imprint on his boots. Thereafter the goose would follow whoever wore the boots. The identity of the goose's mother was learned, but the goose's behavior towards the boots was instinctive.[citation needed]

The term "instinct" in psychology was first used in the 1870s by Wilhelm Wundt. By the close of the 19th century, most repeated behavior was considered instinctual. In a survey of the literature at that time, one researcher chronicled 4,000 human "instincts," having applied this label to any behavior that was repetitive.[citation needed] As research became more rigorous and terms better defined, instinct as an explanation for human behavior became less common. In a conference in 1960, chaired by Frank Beach, a pioneer in comparative psychology, and attended by luminaries in the field, the term was restricted in its application.[citation needed] During the 1960s and 1970s, textbooks still contained some discussion of instincts in reference to human behavior. By the year 2000, a survey of the 12 best selling textbooks in Introductory Psychology revealed only one reference to instincts, and that was in regard to Sigmund Freud's referral to the "id" instincts.[citation needed]. In this sense, instincts appeared to have become regarded as increasingly superfluous in trying to understand human psychological behavior.

Psychologist Abraham Maslow argued that humans no longer have instincts because we have the ability to override them in certain situations. He felt that what is called instinct is often imprecisely defined, and really amounts to strong drives. For Maslow, an instinct is something which cannot be overridden, and therefore while the term may have applied to humans in the past, it no longer does.[3]

The book Instinct (1961) established a number of criteria which distinguish instinctual from other kinds of behavior. To be considered instinctual, a behavior must: a) be automatic, b) be irresistible, c) occur at some point in development, d) be triggered by some event in the environment, e) occur in every member of the species, f) be unmodifiable, and g) govern behavior for which the organism needs no training (although the organism may profit from experience and to that degree the behavior is modifiable).[4]

In a classic paper published in 1972,[5] the psychologist Richard Herrnstein decries Fabre's opinions on instinct (see: In biology section).

In Information behavior: An Evolutionary Instinct (2010, pp.3542), Amanda Spink notes that "currently in the behavioral sciences instinct is generally understood as the innate part of behavior that emerges without any training or education in humans." She claims that the viewpoint that information behavior has an instinctive basis is grounded in the latest thinking on human behavior. Furthermore, she notes that "behaviors such as cooperation, sexual behavior, child rearing and aesthetics are [also] seen as 'evolved psychological mechanisms' with an instinctive basis."[6][7][8] Spink adds that Steven Pinker similarly asserts that language acquisition is instinctive in humans in his book The Language Instinct (1994).

Examples of behaviors that do not require conscious will include many reflexes. The stimulus in a reflex may not require brain activity but instead may travel to the spinal cord as a message that is then transmitted back through the body, tracing a path called the reflex arc. Reflexes are similar to fixed action patterns in that most reflexes meet the criteria of a FAP. However, a fixed action pattern can be processed in the brain as well; a male stickleback's instinctive aggression towards anything red during his mating season is such an example. Examples of instinctive behaviors in humans include many of the primitive reflexes, such as rooting and suckling, behaviors which are present in mammals. In rats, it has been observed that innate responses are related to specific chemicals, and these chemicals are detected by two organs located in the nose: the vomeronasal organ (VNO) and the main olfactory epithelium (MOE).[9]

Some instinctive behaviors depend on maturational processes to appear. For instance, we commonly refer to birds "learning" to fly. However, young birds have been experimentally reared in devices that prevent them from moving their wings until they reached the age at which their cohorts were flying. These birds flew immediately and normally when released, showing that their improvement resulted from neuromuscular maturation and not true learning.[10]

An example of instinct is imprinting[according to whom?]. This is a complex response that involves visual, auditory, and olfactory cues in the environment surrounding an organism. In some cases, imprinting attaches an offspring to its parent, which is a reproductive benefit to offspring survival.[11] If an offspring has attachment to a parent, it is more likely to stay nearby under parental protection. Attached offspring are also more likely to learn from a parental figure when interacting that closely. Reproductive benefits are a driving force behind natural selection.

Environment is an important factor in how innate behavior has evolved. A hypothesis of Michael McCollough, a positive psychologist, explains that environment plays a key role in human behaviors such as forgiveness and revenge. This hypothesis theorizes that various social environments cause either forgiveness or revenge to be prevalent. McCollough relates his theory to game theory.[12] In a tit-for-tat strategy, cooperation and retaliation are comparable to forgiveness and revenge. The choice between the two can be beneficial or detrimental depending on what the partner organism chooses. Though this psychological example of game theory does not have as directly measurable results, it provides an interesting theory of unique thought. From a more biological standpoint, the limbic system is the main control area for response to certain stimuli, which includes a variety of instinctual behavior. The limbic system processes external stimuli related to emotions, social activity, and motivation, which propagates a behavioral response. Some behaviors include maternal care, aggression, defense, and social hierarchy. These behaviors are influenced by sensory inputsight, sound, touch, and smell.

Within the circuitry of the limbic system, there are various places where evolution could have taken place, or could take place in the future. For example, many rodents have receptors in the vomeronasal organ that are explicitly for predator stimuli that specifically relate to that individual species of rodent. The reception of a predatory stimulus usually creates a response of defense or fear.[13] Mating in rats follows a similar mechanism. The vomeronasal organ and the main olfactory epithelium, together called the olfactory system, detect pheromones from the opposite sex. These signals are then sent to the medial amygdala, which disperses the signal to a variety of brain parts. The pathways involved with innate circuitry are extremely specialized and specific.[14] Various organs and sensory receptors are involved in this complex process.

Instinct is a phenomenon that can be investigated from a multitude of angles: genetics, limbic system, nervous pathways, and environment. There are levels of instincts from molecular to groups of individuals that can be studied as well. Extremely specialized systems have evolved to create individuals who exhibit behaviors without learning them. Innate behavior is an important and interesting aspect of the biological world that people come into contact with every day.

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Instinct - Wikipedia

Human sexual activity – Wikipedia

This article is about sexual practices and related social aspects. For broader aspects of sexual behaviour, see Human sexuality. "Sexual activity" and "sexual behavior" redirect here. For sexual activity among other animals, see Animal sexual behaviour.

Human sexual activity, human sexual practice or human sexual behavior is the manner in which humans experience and express their sexuality. People engage in a variety of sexual acts, ranging from activities done alone (e.g., masturbation) to acts with another person (e.g., sexual intercourse, non-penetrative sex, oral sex, etc.) in varying patterns of frequency, for a wide variety of reasons. Sexual activity normally results in sexual arousal and physiological changes in the aroused person, some of which are pronounced while others are more subtle. Sexual activity may also include conduct and activities which are intended to arouse the sexual interest of another or enhance the sex life of another, such as strategies to find or attract partners (courtship and display behavior), or personal interactions between individuals (for instance, foreplay or BDSM). Sexual activity may follow sexual arousal.

Human sexual activity has sociological, cognitive, emotional, behavioral and biological aspects; these include personal bonding, sharing emotions and the physiology of the reproductive system, sex drive, sexual intercourse and sexual behavior in all its forms.

In some cultures, sexual activity is considered acceptable only within marriage, while premarital and extramarital sex are taboo. Some sexual activities are illegal either universally or in some countries or subnational jurisdictions, while some are considered contrary to the norms of certain societies or cultures. Two examples that are criminal offenses in most jurisdictions are sexual assault and sexual activity with a person below the local age of consent.

Sexual activity can be classified in a number of ways. It can be divided into acts which involve one person, also called autoeroticism, such as masturbation, or two or more people such as vaginal sex, anal sex, oral sex or mutual masturbation. If there are more than two participants in the sex act, it may be referred to as group sex. Autoerotic sexual activity can involve use of dildos, vibrators, anal beads, and other sex toys, though these devices can also be used with a partner.

Sexual activity can be classified into the gender and sexual orientation of the participants, as well as by the relationship of the participants. For example, the relationships can be ones of marriage, intimate partners, casual sex partners or anonymous. Sexual activity can be regarded as conventional or as alternative, involving, for example, fetishism, paraphilia, or BDSM activities.[1][2] Fetishism can take many forms ranging from the desire for certain body parts, for example large breasts, armpits or foot worship. The object of desire can often be shoes, boots, lingerie, clothing, leather or rubber items. Some non-conventional autoerotic practices can be dangerous. These include erotic asphyxiation and self-bondage. The potential for injury or even death that exists while engaging in the partnered versions of these fetishes (choking and bondage, respectively) becomes drastically increased in the autoerotic case due to the isolation and lack of assistance in the event of a problem.

Sexual activity can be consensual, which means that both or all participants agree to take part and are of the age that they can consent, or it may take place under force or duress, which is often called sexual assault or rape. In different cultures and countries, various sexual activities may be lawful or illegal in regards to the age, gender, marital status or other factors of the participants, or otherwise contrary to social norms or generally accepted sexual morals.

The physiological responses during sexual stimulation are fairly similar for both men and women and there are four phases.[3]

Sexual dysfunction is the inability to react emotionally or physically to sexual stimulation in a way projected of the average healthy person; it can affect different stages in the sexual response cycles, which are desire, excitement and orgasm.[7] In the media, sexual dysfunction is often associated with men, but in actuality, it is more commonly observed in females (43 percent) than males (31 percent).[8]

Sexual activity can lower blood pressure and overall stress levels, regardless of age.[citation needed] It releases tension, elevates mood, and may create a profound sense of relaxation, especially in the postcoital period. From a biochemical perspective, sex causes the release of endorphins and increases levels of white blood cells that actually boost the immune system. A study published in the journal Biological Psychology described how men who had had sex the previous night responded better to stressful situations, it suggested that if a person is regularly sexual, theyre regularly relaxed, and when the person is relaxed, they cope better with stressful situations.[citation needed] A 2007 study published in the Archives of Sexual Behavior 36, (no. 3 (June 2007): 35768) reported that sexual behavior with a partner on one day significantly predicted lower negative mood and stress, and higher positive mood, on the following day.

People engage in sexual activity for any of a multitude of possible reasons. Although the primary evolutionary purpose of sexual activity is reproduction, research on college students suggested that people have sex for four general reasons: physical attraction, as a means to an end, to increase emotional connection, and to alleviate insecurity.[9]

Most people engage in sexual activity because of pleasure they derive from the arousal of their sexuality, especially if they can achieve orgasm. Sexual arousal can also be experienced from foreplay and flirting, and from fetish or BDSM activities,[1][10] or other erotic activities. Most commonly, people engage in sexual activity because of the sexual desire generated by a person to whom they feel sexual attraction; but they may engage in sexual activity for the physical satisfaction they achieve in the absence of attraction for another, as in the case of casual or social sex.[11] At times, a person may engage in a sexual activity solely for the sexual pleasure of their partner, such as because of an obligation they may have to the partner or because of love, sympathy or pity they may feel for the partner.

A person may engage in sexual activity for purely monetary considerations, or to obtain some advantage from either the partner or the activity. A man and woman may engage in sexual intercourse with the objective of conception. Some people engage in hate sex, which occurs between two people who strongly dislike or annoy each other. It is related to the idea that opposition between two people can heighten sexual tension, attraction and interest.[12]

It has been shown that sexual activity plays a large part in the interaction of social species. Joan Roughgarden, in her book Diversity, Gender, and Sexuality in Nature and People, postulates that this applies equally to humans as it does to other social species. She explores the purpose of sexual activity and demonstrates that there are many functions facilitated by such activity including pair bonding, group bonding, dispute resolution and reproduction.[13]

Research has found that people also engage in sexual activity for reasons associated with self-determination theory. The self-determination theory can be applied to a sexual relationship when the participants have positive feelings associated with the relationship. These participants do not feel guilty or coerced into the partnership.[14] Researchers have proposed the model of self-determined sexual motivation. The purpose of this model is to connect self-determination and sexual motivation.[15] This model has helped to explain how people are sexually motivated when involved in self-determined dating relationships. This model also links the positive outcomes, (satisfying the need for autonomy, competence, and relatedness) gained from sexual motivations.[15]

According to the completed research associated with this model, it was found that people of both sexes who engaged in sexual activity for self-determined motivation had more positive psychological well-being.[15] While engaging in sexual activity for self-determined reasons, the participants also had a higher need for fulfillment. When this need was satisfied, they felt better about themselves. This was correlated with greater closeness to their partner and higher overall satisfaction in their relationship.[15] Though both sexes engaged in sexual activity for self-determined reasons, there were some differences found between males and females. It was concluded that females had more motivation than males to engage in sexual activity for self-determined reasons.[15] Females also had higher satisfaction and relationship quality than males did from the sexual activity.[15] Overall, research concluded that psychological well-being, sexual motivation, and sexual satisfaction were all positively correlated when dating couples partook in sexual activity for self-determined reasons.[15]

The frequency of sexual activity might range from zero (sexual abstinence) to 15 or 20 times a week.[16] In the United States, the average frequency of sexual intercourse for married couples is 2 to 3 times a week.[17] It is generally recognized that postmenopausal women experience declines in frequency of sexual intercourse[18] and that average frequency of intercourse declines with age. According to the Kinsey Institute, the average frequency of sexual intercourse in the US is 112 times per year (age 1829), 86 times per year (age 3039), and 69 times per year (age 4049).[19]

The age at which adolescents tend to become sexually active varies considerably between different cultures and from time to time. (See Prevalence of virginity.) The first sexual act of a child or adolescent is sometimes referred to as the sexualization of the child, and may be considered as a milestone or a change of status, as the loss of virginity or innocence. Youth are legally free to have intercourse after they reach the age of consent.

A 1999 survey of students indicated that approximately 40% of ninth graders across the United States report having had sexual intercourse. This figure rises with each grade. Males are more sexually active than females at each of the grade levels surveyed. Sexual activity of young adolescents differs in ethnicity as well. A higher percent of African American and Hispanic adolescents are sexually active than White adolescents.[20]

Research on sexual frequency has also been conducted solely on female adolescents who engage in sexual activity. Female adolescents tended to engage in more sexual activity due to positive mood. In female teenagers, engaging in sexual activity was directly positively correlated with being older, greater sexual activity in the previous week or prior day, and more positive mood the previous day or the same day as the sexual activity occurred.[21] Decreased sexual activity was associated with prior or current day negative mood or vaginal bleeding.[21]

Although opinions differ, others[who?] suggest that sexual activity is an essential part of humans, and that teenagers need to experience sex. Sexual experiences help teenagers understand pleasure and satisfaction.[22] In relation to hedonic and eudaimonic well-being, teenagers can positively benefit from sexual activity according to one particular research study. In the United States[which?] of America, a cross-sectional study of teenagers was completed.[when?] Teenagers who had their first sexual experience at age 16 revealed a higher well-being than those who were sexually inexperienced or who were first sexually active at a later age of 17.[22] Furthermore, teenagers who had their first sexual experience at age 15 or younger, or who had many sexual partners were not negatively affected and did not have associated lower well-being.[22]

Sexual activity is a normal physiological function,[23] but like other physical activity, it comes with risks. There are four main types of risks that may arise from sexual activity: unwanted pregnancy, contracting a sexually transmitted infection (STI/STD), physical injury, and psychological injury.

Any sexual activity that involves the introduction of semen into a woman's vagina, such as during sexual intercourse, or even contact of semen with her vulva, may result in a pregnancy.[24] To reduce the risk of unintended pregnancies, some people who engage in penile-vaginal sex may use contraception, such as birth control pills, a condom, diaphragms, spermicides, hormonal contraception or sterilization.[25] The effectiveness of the various contraceptive methods in avoiding pregnancy varies considerably.

Sexual activity that involves skin-to-skin contact, exposure to an infected person's bodily fluids or mucosal membranes[26] carries the risk of contracting a sexually transmitted infection. People may not be able to detect that their sexual partner has one or more STIs, for example if they are asymptomatic (show no symptoms).[27][28] The risk of STIs can be reduced by safe sex practices, such as using condoms. Both partners may opt be tested for STIs before engaging in sex.[29] There may also be an increased risk of contracting a STI when having sex with multiple partners.

Some STIs can also be contracted by using IV drug needles after their use by an infected person, as well as through childbirth or breastfeeding.

Typically, older men and women maintaining interest in sexual interest and activity could be therapeutic; it is a way of expressing their love and care for one another. Factors such as biological and psychological factors, diseases, mental conditions, boredom with the relationship, and widowhood have been found to contribute with the common decrease in sexual interest and activity in old age. National sex surveys given in Finland in the 1990s revealed aging men had a higher incidence of sexual intercourse compared to aging women and that women were more likely to report a lack of sexual desire compared to men. Regression analysis, factors considered important to female sexual activity included: sexual desire, valuing sexuality, and a healthy partner, while high sexual self-esteem, good health, and active sexual history were important to male sexual activity. Both aging genders agreed they needed good health, good sexual functioning, positive sexual self-esteem, and a sexually skilful partner to maintain sexual desire.[30]

Heterosexuality is the romantic or sexual attraction to the opposite sex. Heterosexual sexual practices are subject to laws in many places. In some countries, mostly those where religion has a strong influence on social policy, marriage laws serve the purpose of encouraging people to have sex only within marriage. Sodomy laws were seen as discouraging same-sex sexual practices, but may affect opposite-sex sexual practices. Laws also ban adults from committing sexual abuse, committing sexual acts with anyone under an age of consent, performing sexual activities in public, and engaging in sexual activities for money (prostitution). Though these laws cover both same-sex and opposite-sex sexual activities, they may differ in regard to punishment, and may be more frequently (or exclusively) enforced on those who engage in same-sex sexual activities.[31]

Different-sex sexual practices may be monogamous, serially monogamous, or polyamorous, and, depending on the definition of sexual practice, abstinent or autoerotic (including masturbation). Additionally, different religious and political movements have tried to influence or control changes in sexual practices including courting and marriage, though in most countries changes occur at a slow rate.

Homosexuality is the romantic or sexual attraction to the same sex. People with a homosexual orientation can express their sexuality in a variety of ways, and may or may not express it in their behaviors.[32] Research indicates that many gay men and lesbians want, and succeed in having, committed and durable relationships. For example, survey data indicate that between 40% and 60% of gay men and between 45% and 80% of lesbians are currently involved in a romantic relationship.[33]

It is possible for a person whose sexual identity is mainly heterosexual to engage in sexual acts with people of the same sex. For example, mutual masturbation in the context of what may be considered normal heterosexual teen development. Gay and lesbian people who pretend to be heterosexual are often referred to as being closeted (hiding their sexuality in "the closet"). "Closet case" is a derogatory term used to refer to people who hide their sexuality. Making that orientation public can be called "coming out of the closet" in the case of voluntary disclosure or "outing" in the case of disclosure by others against the subject's wishes (or without their knowledge). Among some communities (called "men on the DL" or "down-low"), same-sex sexual behavior is sometimes viewed as solely for physical pleasure. Men who have sex with men, as well as women who have sex with women, or men on the "down-low" may engage in sex acts with members of the same sex while continuing sexual and romantic relationships with the opposite sex.

People who engage exclusively in same-sex sexual practices may not identify themselves as gay or lesbian. In sex-segregated environments, individuals may seek relationships with others of their own gender (known as situational homosexuality). In other cases, some people may experiment or explore their sexuality with same (and/or different) sex sexual activity before defining their sexual identity. Despite stereotypes and common misconceptions, there are no forms of sexual acts exclusive to same-sex sexual behavior that cannot also be found in opposite-sex sexual behavior, except those involving the meeting of the genitalia between same-sex partners tribadism (generally vulva-to-vulva rubbing, commonly known by its "scissoring" position) and frot (generally penis-to-penis rubbing).

People who have a romantic or sexual attraction to both sexes are referred to as bisexual.[34][35] People who have a distinct but not exclusive preference for one sex/gender over the other may also identify themselves as bisexual.[36] Like gay and lesbian individuals, bisexual people who pretend to be heterosexual are often referred to as being closeted.

Pansexuality (also referred to as omnisexuality)[37] may or may not be subsumed under bisexuality, with some sources stating that bisexuality encompasses sexual or romantic attraction to all gender identities.[38][39] Pansexuality is characterized by the potential for aesthetic attraction, romantic love, or sexual desire towards people without regard for their gender identity or biological sex.[40] Some pansexuals suggest that they are gender-blind; that gender and sex are insignificant or irrelevant in determining whether they will be sexually attracted to others.[41] As defined in the Oxford English Dictionary, pansexuality "encompasses all kinds of sexuality; not limited or inhibited in sexual choice with regards to gender or practice".[42]

Most people experiment with a range of sexual activities during their lives, although they tend to engage in only a few of these regularly. Some people enjoy many different sexual activities, while others avoid sexual activities altogether for religious or other reasons (see chastity, sexual abstinence, asexuality). Some prefer monogamous relationships for sex, while others may prefer many different partners throughout their lives.

Alex Comfort and others propose three potential social aspects of intercourse in humans, which are not mutually exclusive: reproductive, relational, and recreational.[43] The development of the contraceptive pill and other highly effective forms of contraception in the mid- and late 20th century has increased people's ability to segregate these three functions, which still overlap a great deal and in complex patterns. For example: A fertile couple may have intercourse while using contraception to experience sexual pleasure (recreational) and also as a means of emotional intimacy (relational), thus deepening their bonding, making their relationship more stable and more capable of sustaining children in the future (deferred reproductive). This same couple may emphasize different aspects of intercourse on different occasions, being playful during one episode of intercourse (recreational), experiencing deep emotional connection on another occasion (relational), and later, after discontinuing contraception, seeking to achieve pregnancy (reproductive, or more likely reproductive and relational).

Most world religions have sought to address the moral issues that arise from people's sexuality in society and in human interactions. Each major religion has developed moral codes covering issues of sexuality, morality, ethics etc. Though these moral codes do not address issues of sexuality directly, they seek to regulate the situations which can give rise to sexual interest and to influence people's sexual activities and practices. However, the effect of religious teaching has at times been limited. For example, though most religions disapprove of extramarital sexual relations, it has always been widely practiced. Nevertheless, these religious codes have always had a strong influence on peoples' attitudes to issues of modesty in dress, behavior, speech etc.

On the other hand, some people adopt the view that pleasure is its own justification for sexual activity. Hedonism is a school of thought which argues that pleasure is the only intrinsic good.[44]

Human sexual activity, like many other kinds of activity engaged in by humans, is generally influenced by social rules that are culturally specific and vary widely. These social rules are referred to as sexual morality (what can and can not be done by society's rules) and sexual norms (what is and is not expected).

Sexual ethics, morals, and norms relate to issues including deception/honesty, legality, fidelity and consent. Some activities, known as sex crimes in some locations, are illegal in some jurisdictions, including those conducted between (or among) consenting and competent adults (examples include sodomy law and adult-adult incest).

Some people who are in a relationship but want to hide polygamous activity (possibly of opposite sexual orientation) from their partner, may solicit consensual sexual activity with others through personal contacts, online chat rooms, or, advertising in select media.

Swinging, on the other hand, involves singles or partners in a committed relationship engaging in sexual activities with others as a recreational or social activity.[45] The increasing popularity of swinging is regarded by some as arising from the upsurge in sexual activity during the sexual revolution of the 1960s. Swinging sexual activity can take place in a sex club, also known as a swinger club (not to be confused with a strip club).[46]

Some people engage in various sexual activities as a business transaction. When this involves having sex with, or performing certain actual sexual acts for another person in exchange for money or something of value, it is called prostitution. Other aspects of the adult industry include phone sex operators, strip clubs, and pornography.

Social gender roles can influence sexual behavior as well as the reaction of individuals and communities to certain incidents; the World Health Organization states that, "Sexual violence is also more likely to occur where beliefs in male sexual entitlement are strong, where gender roles are more rigid, and in countries experiencing high rates of other types of violence."[47] Some societies, such as those where the concepts of family honor and female chastity are very strong, may practice violent control of female sexuality, through practices such as honor killings and female genital mutilation.[48][49]

The relation between gender equality and sexual expression is recognized, and promotion of equity between men and women is crucial for attaining sexual and reproductive health, as stated by the UN International Conference on Population and Development Program of Action:[50]

BDSM is a variety of erotic practices or roleplaying involving bondage, dominance and submission, sadomasochism, and other interpersonal dynamics. Given the wide range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent on self-identification and shared experience. BDSM communities generally welcome anyone with a non-normative streak who identifies with the community; this may include cross-dressers, extreme body modification enthusiasts, animal players, latex or rubber aficionados, and others.

B/D, a form of BDSM, is bondage and discipline. Bondage includes the restraint of the body or mind.[51] D/S means "dominant and submissive." A dominant is someone who takes control of someone who wishes to give up control. A submissive is someone who gives up the control to a person who wishes to take control.[51] S/M (sadism and masochism) means an individual who takes pleasure in the humiliation or pain of others. Masochism means an individual who takes pleasure from their own pain and/or humiliation.[51]

Unlike the usual "power neutral" relationships and play styles commonly followed by couples, activities and relationships within a BDSM context are often characterized by the participants' taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners becomes essential. Participants who exert sexual dominance over their partners are known as dominants or tops, while participants who take the passive, receiving, or obedient role are known as submissives or bottoms.

Individuals are also sometimes abbreviated when referred to in writing, so a dominant person may be referred to as a "dom" for a man or a woman. Sometimes a woman may choose to use the female specific term "Domme". Both terms are pronounced the same when spoken. Individuals who can change between top/dominant and bottom/submissive roleswhether from relationship to relationship or within a given relationshipare known as switches. The precise definition of roles and self-identification is a common subject of debate within the community.[52]

In a 2013 study, the researchers suggest that BDSM is a sexual act where they play role games, use restraint, use power exchange, use suppression and pain is sometimes involved depending on individual(s).[53] The study indicates that, in the past, BDSM has been seen as maladaptive to one's psychological health, but that this may be incorrect. According to the study, one who participates in BDSM can have greater strength socially, mentally and have greater independence than those who do not practice BDSM.[53] It states that people who participate in BDSM play actually have higher subjective well-being, and that this might be due to the fact that BDSM play requires extensive communication. Before any sexual act occurs, the partners must discuss their agreement of their relationship. They discuss how long the play will last, the intensity, their actions, what each participant needs and/or desires. The sexual acts are all consensual and pleasurable to both parties.[53]

In a 2015 study, BDSM relationships were suggested to have a higher level of connection, intimacy, trust and communication compared to individuals who do not practice BDSM.[51] The study suggests that dominants and submissives exchange control for each other's pleasure and to satisfy a need. They mention that both parties enjoys pleasing their partner in any way they can. Submissive and Dominants who participated in their research, felt that this is one of the best things about BDSM. It gives a submissive pleasure to do things in general for their dominant. Where Dominant enjoys making their encounters all about the submissive. They enjoy doing things that makes their submissive happy. Their findings suggest that submissives and dominants found BDSM play more pleasurable and fun. BDSM was also suggested to improve personal growth, romantic relationships, their sense of community, their sense of self, the dominants confidence, and help an individual cope with everyday things by giving them a psychological release.[51]

There are many laws and social customs which prohibit, or in some way affect sexual activities. These laws and customs vary from country to country, and have varied over time. They cover, for example, a prohibition to non-consensual sex, to sex outside of marriage, to sexual activity in public, besides many others. Many of these restrictions are non-controversial, but some have been the subject of public debate.

Most societies consider it a serious crime to force someone to engage in sexual acts or to engage in sexual activity with someone who does not consent. This is called sexual assault, and if sexual penetration occurs it is called rape, the most serious kind of sexual assault. The details of this distinction may vary among different legal jurisdictions. Also, what constitutes effective consent in sexual matters varies from culture to culture and is frequently debated. Laws regulating the minimum age at which a person can consent to have sex (age of consent) are frequently the subject of debate, as is adolescent sexual behavior in general. Some societies have forced marriage, where consent may not be required.

Many locales have laws that limit or prohibit same-sex sexual activity.

In the West, sex before marriage is not illegal. There are social taboos and many religions condemn pre-marital sex. In many Muslim countries, such as Saudi Arabia, Pakistan,[54] Afghanistan,[55][56][57] Iran,[57] Kuwait,[58] Maldives,[59] Morocco,[60] Oman,[61] Mauritania,[62] United Arab Emirates,[63][64] Sudan,[65] Yemen,[66] any form of sexual activity outside marriage is illegal. Those found guilty, especially women, may be forced to wed the sexual partner, publicly beaten, or stoned to death.[67] In many African and native tribes, sexual activity is not viewed as a privilege or right of a married couple, but rather as the unification of bodies and is thus not frowned upon.[68]

Other studies have analyzed the changing attitudes about sex that American adolescents have outside of marriage. Adolescents were asked how they felt about oral and vaginal sex in relation to their health, social, and emotional well-being. Overall, teenagers felt that oral sex was viewed as more socially positive amongst their demographic.[69] Results stated that teenagers believed that oral sex for dating and non-dating adolescents was less threatening to their overall values and beliefs than vaginal sex was.[69] When asked, teenagers who participated in the research viewed oral sex as more acceptable to their peers, and their personal values than vaginal sex.[69]

The laws of each jurisdiction set the minimum age at which a young person is allowed to engage in sexual activity.[70] This age of consent is typically between 14 and 18 years, but laws vary. In many jurisdictions, age of consent is a person's mental or functional age.[71][71][72][73] As a result, those above the set age of consent may still be considered unable to legally consent due to mental immaturity.[71][72][73][74][75] Many jurisdictions regard any sexual activity by an adult involving a child as child sexual abuse.

Age of consent may vary by the type of sexual act, the sex of the actors, or other restrictions such as abuse of a position of trust. Some jurisdictions also make allowances for young people engaged in sexual acts with each other.[76]

Most jurisdictions prohibit sexual activity between certain close relatives. These laws vary to some extent; such acts are called incestuous.

Non-consensual sexual activity or subjecting an unwilling person to witnessing a sexual activity are forms of sexual abuse, as well as (in many countries) certain non-consensual paraphilias such as frotteurism, telephone scatophilia (indecent phonecalls), and non-consensual exhibitionism and voyeurism (known as "indecent exposure" and "peeping tom" respectively).[77]

People sometimes exchange sex for money or access to other resources. This practice, called prostitution, takes place under many varied circumstances. The person who receives payment for sexual services is called a prostitute and the person who receives such services is known by a multitude of terms, including (and most commonly) "john." Prostitution is one of the branches of the sex industry. The legal status of prostitution varies from country to country, from being a punishable crime to a regulated profession. Estimates place the annual revenue generated from the global prostitution industry to be over $100 billion.[78] Prostitution is sometimes referred to as "the world's oldest profession".[79] Prostitution may be a voluntary individual activity or facilitated or forced by pimps.

Survival sex is a form of prostitution engaged in by people in need, usually when homeless or otherwise disadvantaged people trade sex for food, a place to sleep, or other basic needs, or for drugs.[80] The term is used by sex trade and poverty researchers and aid workers.[81][82]

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