The term "erection" refers to the "enlargement and hardening of erectile organs or tissues (penis, clitoris, nipples) due to massive vasodilation; in this article we will focus on penile erection.
Penile erection: how it happens and what it depends on
An erection is a spinal reflex that leads to an increase in the turgor and size of the penis. This phenomenon, which reflects the state of male sexual arousal, is supported by the integration of stimuli of various kinds.
Physiologically speaking, an erection is the result of a fine interaction between elements of a vascular, hormonal, nervous, psychological and genitourinary nature. In its simplest form, the erection reflex, which is under the control of the autonomic nervous system and represents therefore an involuntary event arises from the tactile activation of the glans mechanoreceptors or other erogenous zones. These stimuli are then transferred to the spino-sacral control centers, which process them, triggering those biochemical events that underlie the erection. The spinal centers located a little higher up, at the height of the first and second lumbar vertebrae, can also reach signals produced in the higher cerebral centers, following erotic stimuli of a visual, auditory, olfactory or psychological nature.
The integration of all these impulses, including those of an inhibitory nature, determines a response of the spinal control centers. When excitatory signals prevail, 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 efferents are stimulated, which act in a diametrically opposite way, increasing the blood flow to the penis and causing its erection.
When the excitatory stimuli cease, the GMPc is degraded by a specific enzyme, called phosphodiesterase and the detumescence phase is entered. The Viagra it acts at this level, inhibiting the activity of these enzymes and ensuring a more consistent and prolonged erection. The same goes for tadalafil (trade 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 significant amounts of blood, increasing in size. The increase in volume also causes a rise in blood pressure, which blocks venous reflux and leads to the trapping of blood in the corpora cavernosa.
Below them runs a third structure: the corpus spongiosum, which accompanies the urethra and extends anteriorly to form the glans. During erection, the corpus spongiosum exerts a lower pressure than the corpora cavernosa, so as not to occlude "urethra and allow the passage of sperm at the time of ejaculation.
Erectile dysfunction
Impotence, better defined as erectile dysfunction, is the inability to obtain and maintain an erection satisfactory 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 erection (psychic, nervous, endocrine, circulatory, anatomical, etc.).
Often and willingly, especially from late adulthood onwards, erectile dysfunction represents the unpleasant consequence of cardiovascular, endocrine (diabetes, "andropause") or arterial (arteriosclerosis) diseases. 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, sedentary lifestyle and diabetes.
