The terminology for the complexities of human sexual activity is discussed and the male and female sexual arousal to orgasm is described with its underlying physiological mechanisms. The original four-phased human sexual response cycle of Masters & Johnson (Excitation, Plateau, Orgasm, Resolution) is now modified by amalgamation of the plateau phase into the excitation phase and the addition of two desire phases, one spontaneous (proactive) the other activated by arousal per se (reactive). The relation between genital arousal and subjective arousal is reviewed for males and females. In males, erection and subjective arousal usually have good concordance but in females increased vaginal blood flow and lubrication can occur without any concomitant subjective arousal even with sexually aversive stimuli. The subjective feeling of sexual arousal in women is now regarded as more complex than stimuli from the genitals, involving the contextual meaning and content of the stimuli. Imaging studies have revealed multiple areas of the brain that become involved during sexual arousal and at orgasm. However, different studies using different techniques and analyses have given conflicting accounts of which areas are activated and which are deactivated, and it is not possible at present to finalize the position.
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The terminology of human sexual activity
Many authors use the terms ‘sexual arousal’ and ‘sexual excitement’ synonymously but it is useful to keep sexual arousal (a state) to denote physiological changes and sexual excitement as the subjective awareness of the arousal. Greater difficulty occurs when it comes to describing the central mental process creating the subjective awareness of arousal. The literature has sexual drive, desire, interest, appetite, motivation and libido (see Levin2 for a detailed discussion). Sexual drive is the
Sexual response cycle
The sequence of events that characterizes the progression from the sexually unaroused to the aroused state and the resolution of these changes is described as the human sexual response cycle,5 with genital and non-genital components. The latter include increased heart rate, blood pressure and respiration, nipple erection, myotonia and dilated pupils.
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The biological purpose of the sexual response in men is to enable sperm to be introduced into the vagina, while the genital changes occurring in
Spinal cord mechanisms
Sensory input arising from stimulation of the external genitalia is conveyed in the pudendal nerve to the medial central grey matter of the lumbosacral spine and the information is relayed to supraspinal sites in the spinothalamic and spinoreticular pathways. Two different pathways carry the sensory information from the glans via the dorsal nerve of the penis. The sensory fibres of the pudendal nerve conveys the information to the spinal cord, and the information also travels to the hypogastric
Brain imaging during sexual arousal and orgasm
Apart from the very limited information available from subjects with brain lesions, those with epilepsy and the rare cases of electrical stimulation of the brain (see Levin2 for references), animal studies, especially in rodents, have been the major source of information about the central mechanisms controlling sexual arousal/behaviour. While numerous neurotransmitters are implicated in the complex mechanisms of sexual activity (cholinergic, adrenergic, vipergic, oxyntergic, prolactinergic),
Genital arousal
Genital arousal in both sexes is essentially a vasocongestive and neuromuscular event controlled by facilitatory parasympathetic and inhibiting sympathetic neural mechanisms. The primary changes are penile erection in men and clitoral tumescence, genital vasocongestion and increased vaginal lubrication in women. The increase in heart rate and blood pressure that occurs during sexual arousal provides the increased blood flow to the genitals.
Ejaculation and orgasm
Ejaculation in the male is the process by which spermatozoa contained within seminal fluid are ejected forcefully from the urethral meatus. Some women experience a discharge of fluid from the urethra at orgasm and high levels of sexual arousal, often by stimulation of the so-called G-spot on the anterior wall of the vagina, and this has been termed ‘female ejaculation’. Whether this discharge is urine or a product of the paraurethral glands or a mixture of both continues to be debated.18
Hormones and human sexuality
An account of the role of hormones in human sexuality is too complex to be dealt with in this contribution but their importance should not be overlooked. Briefly, the sex steroids, especially androgens and oestrogens, have essential developmental (organisational), maintenance and activational functions in both males and females. Oestrogens are more involved in female sexuality, especially the development and maintenance of genitalia and breasts. Androgens, however, are important in both male
Conclusion
Sexual functioning involves an integrated series of physiological processes with complicated peripheral and central control systems. Our understanding of the physiology of the peripheral events in the male is advanced and we are now beginning to elucidate those of the female. Much of our knowledge of central mechanisms is derived from animal studies, and with current advances in imaging technology it is becoming possible to assess the relevance of findings in animals to the human state. A
References (20)
J. Redouté et al.
Brain processing of visual sex stimuli in treated and untreated hypogonadal subjects
Psychoneuroendocrinology
(2005)
A. Riley et al.
Relevant issues in the diagnosis and management of psychosexual disorders
Primary Care Psychiatry
(1999)
R.J. Levin
Human male sexuality: appetite and arousal, desire and drive
A. Riley
Problems of the sexual response cycle
Journal of the Diplomates of the Royal College of Obstetricians and Gynaecologists
(1997)
R. Basson
Biopsychosocial models of women’s sexual response: applications to management of desire disorders
Sex Relationship Ther
(2003)
W. Masters et al.
Human sexual response
(1966)
R.J. Levin
Sexual arousal – its physiological roles in human reproduction
Annu Rev Sex Res
(2005)
R.J. Levin
Sexual desire and the deconstruction and reconstruction of the human sexual response model of Masters and Johnson
G. Holstege
Central nervous system control of ejaculation
World J Urol
(2005)
R.G. Parades et al.
Has dopamine a physiological role in the central control of sexual behaviour? A critical review of the evidence
Prog Neurobiol
(2004)
There are more references available in the full text version of this article.
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