The term "erection" refers to the increase in volume and the hardening of erectile organs or tissues (penis, clitoris, nipples) due to massive vasodilation; in this article we will focus on penile erection.
Penis erection: how it happens and what it depends on
An erection is a spinal reflex that leads to an increase in turgor and the size of the penis. This phenomenon, which reflects the state of male sexual excitement, is supported by the integration of stimuli of various kinds.
Physiologically speaking, erection is the result of a fine interaction between vascular, hormonal, nervous, psychological and genitourinary elements. In its simplest form, the reflection of the erection, which is under the control of the autonomic nervous system and therefore represents an involuntary event, springs from the tactile activation of the mechanoreceptors of the glans or other erogenous zones. These stimuli are then transferred to the spino-sacral control centers, which process them, triggering those biochemical events underlying the erection. At the spinal centers located a little higher up, at the level of the first and second lumbar vertebrae, signals may also be produced in the upper brain centers, following erotic stimuli of a visual, auditory, olfactory or psychological nature.
The integration of all these impulses, including those of inhibitory nature, determines a response of the spinal control centers. When the excitatory signals prevail, the sympathetic efferences are inhibited, normally responsible for the vasoconstriction of the penile arteries and the flaccidity of the organ. At the same time the parasympathetic efferences are stimulated, which act in a diametrically opposite manner, increasing the blood flow to the penis and determining its erection.
When excitatory stimuli cease to exist, GMPc is degraded by a specific enzyme called phosphodiesterase and enters the detumescence phase. Viagra acts at this level, inhibiting the activity of these enzymes and guaranteeing a more consistent and prolonged erection. The same goes for tadalafil (commercial name Cialis ), which has a longer effect, and for vardenafil (trade name Levitra ).
The corpora cavernosa constitute the two erectile vascular organs of the penis and are in fact comparable to sponges. When the arteriolar and trabecular walls of the corpora cavernosa are released, they incorporate considerable amounts of blood, increasing in size. The increase in volume also determines a pressure rise, which blocks venous reflux and leads to the entrapment of blood in the corpora cavernosa.
Below them runs a third structure: the spongy body, which accompanies the urethra and extends anteriorly to form the glans. During erection, the cancellous body exerts less pressure than the corpora cavernosa, so as not to obstruct the urethra and allow the passage of sperm at the time of ejaculation.
Erectile dysfunction
Impotence, better defined as erectile dysfunction, is the inability to achieve and maintain a satisfactory erection for sexual activity. This dysfunction represents the clinical expression of a problem that can affect one or multiple mechanisms involved in the birth and maintenance of an erection (psychic, nervous, endocrine, circulatory, anatomical sphere, etc.).
More often than not, especially from late adulthood onwards, erectile dysfunction represents the unpleasant consequence of cardiovascular, endocrine (diabetes, "andropause") or arterial (arteriosclerosis) pathologies. The main risk factors to be controlled, from an early age, to enjoy a vigorous and satisfactory erection are therefore represented by hypertension, dyslipidemia, smoking, a sedentary lifestyle and diabetes.
