Academic literature on the topic 'Sexual attraction – Physiological aspects'

Sexual dimorphism of the adult brain regulates sex-dependent functions including reproductive and neuroendocrine activities in rodents. It is determined by sex steroid hormones during a critical perinatal period in female and male rodents. Sex steroids act on each nuclear receptor in the brain and control different physiological and neuroendocrine functions and behaviors. Several regions of the brain show evident morphological sex differences that are involved in their physiological functions. This review addresses and focuses largely on the role of sex-dependent differences in the brain, and their crucial functions in animal models. Particularly, recent intriguing data concerning the diversity of neuronal functions and sexual dimorphism are discussed.

Blushing is unique to humans. So Darwin could not show it had evolved by studying its occurrence in animals. Neither do infants blush. Hence, unlike crying, it was not easily shown to be innate. Furthermore its triggers appear to be immaterial. Expression solves the problem of why and when people blush by hypothesizing a reflexive process of reading: I blush because I read you as reading and judging me—my appearance, or conduct. This dynamic of meta-recognition or self-attention requires the construction of a complex theory of human agency, involving: a dual self; the operation of innate sympathy; a physiological hypothesis; and an evolutionary derivation. Meta-recognition underpinned Darwin’s understanding of sexual attraction, group cohesion, and conscience. It also served as a formative influence on later psychologies of symbolic interaction.

Sexuality is a complex concept encompassing far more than the simple sexual act. Sexuality in fact includes the physiological, behavioural and relational aspects of human sexual life, which are variously influenced by psychological factors (e.g. sexual fantasies, desire, arousal, psychosexual orientation, and the choice of the sexual object), as well as social and organic (vascular, nervous, and endocrine) factors. From a functional point of view, a normal penile erection may be defined as an erection which permits the penetration of a lubricated vagina without additional assistance. Concerning the erectile mechanism, the haemodynamic changes in the penis require a high degree of central and peripheral nervous coordinated control and an unaffected endocrine system.

Puberty may be defined as the physiological process resulting in the attainment of sexual maturity and reproductive capacity. Puberty is an integral component of the evaluation and treatment of endocrine disorders in children and adolescents. Not only does it impact on sexual maturation, but it has other effects with lifelong consequences, including linear growth, changes in body composition, and skeletal mineralization. Patients with disorders of puberty, including precocious and delayed puberty, make up a large percentage of the children and adolescents who consult paediatric endocrinologists. An understanding of delayed or absent puberty requires a foundation in the normal processes regulating the onset of puberty, and factors essential for its progression and completion. In this chapter, we will first review the mechanisms of normal growth and puberty, particularly with regard to their interdependence. We shall then discuss the differential diagnosis of delayed or absent puberty, and present diagnostic algorithms for hypergonadotropic and hypogonadotropic hypogonadism, emphasizing some gender-specific aspects.

Trauma- and stressor-related disorders occur following exposure to a traumatic or other stressful event. They differ according to the timing of exposure and age at manifestation. Post-traumatic stress disorder (PTSD) develops following exposure to actual or threatened death, serious injury, or sexual assault. Intrusions, distressing dreams, dissociative reactions (flashbacks), intense psychological distress, and physiological stress responses at exposure to internal of external cues that symbolize aspects of the traumatic event are typical for PTSD. Behaviourally, PTSD reflects a strategy of defence involving avoidance, attentive immobility, withdrawal, aggressive defence, appeasement, and tonic immobility, some of which are ancient vertebrate heritage. These defence mechanisms are preceded by heightened vigilance and risk assessment. Persistent stress responses often occur when important biosocial goals had been thwarted by the traumatic event. Species with long life-history patterns may be more vulnerable to developing PTSD than species with short life cycles.

The previous chapter provided a detailed description of the currents underlying the generation and propagation of action potentials in the squid giant axon. The Hodgkin-Huxley (1952d) model captures these events in terms of the dynamical behavior of four variables: the membrane potential and three state variables determining the state of the fast sodium and the delayed potassium conductances. This quantitative, conductance-based formalism reproduces the physiological data remarkably well and has been extremely fertile in terms of providing a mathematical framework for modeling neuronal excitability throughout the animal kingdom (for the current state of the art, see McKenna, Davis, and Zornetzer, 1992; Bower and Beeman, 1998; Koch and Segev, 1998). Collectively, these models express the complex dynamical behaviors observed experimentally, including pulse generation and threshold behavior, adaptation, bursting, bistability, plateau potentials, hysteresis, and many more. However, these models are difficult to construct and require detailed knowledge of the kinetics of the individual ionic currents. The large number of associated activation and inactivation functions and other parameters usually obscures the contributions of particular features (e.g., the activation range of the sodium activation particle) toward the observed dynamic phenomena. Even after many years of experience in recording from neurons or modeling them, it is a dicey business predicting the effect that varying one parameter, say, the amplitude of the calcium-dependent slow potassium current (Chap. 9), has on the overall behavior of the model. This precludes the development of insight and intuition, since the numerical complexity of these models prevents one from understanding which important features in the model are responsible for a particular phenomenon and which are irrelevant. Qualitative models of neuronal excitability, capturing some of the topological aspects of neuronal dynamics but at a much reduced complexity, can be very helpful in this regard, since they highlight the crucial features responsible for a particular behavior. By topological aspects we mean those properties that remain unchanged in spite of quantitative changes in the underlying system. These typically include the existence of stable solutions and their basins of attraction, limit cycles, bistability, and the existence of strange attractors.