The Arousal Phase

Physiological changes and vasocongestion in women.

After desire, the arousal phase ensues, characterized by the translation of psychological and physical stimulation into observable bodily responses.

The central biological mechanism is vasocongestion, an increase in blood flow to the genital tissues.

In the female, the primary sign is vaginal lubrication, which is produced by a process of transudation through the vaginal walls, which also begin to expand in length and width.

Simultaneously, the vulva undergoes remarkable changes: the labia majora and labia minora swell due to blood engorgement, increasing in size and spreading apart to facilitate access to the introitus. The clitoris also swells, increasing in diameter.

Extragenitally, the nipples become erect and a sexual flushing of the skin may appear.

It is important to note that anxiety or distraction can interrupt this hydraulic process, stopping lubrication even if there is physical stimulation.

Erectile response and genital changes in men

In the male, the dominant manifestation of the arousal phase is penile erection.

This phenomenon is the direct result of vasocongestion in the corpora cavernosa.

In addition to the hardening and elevation of the penis, the scrotum thickens and tightens, causing the testicles to rise partially toward the perineum and increase slightly in size.

As in the female, the skin of the genitalia may darken due to the influx of blood.

It is essential to educate patients about the involuntary nature of these changes; erection is not an act of conscious volition, but an autonomic response.

Therefore, the pressure to "achieve" an erection often has the opposite effect, activating the sympathetic (alert) nervous system which inhibits the parasympathetic response necessary for arousal.

Psychological factors blocking the physical response

The most common obstacle in this phase is the "bystander role" phenomenon. It occurs when the person dissociates from the sensory experience to critically self-observe: "Am I doing it right?", "Is it hard enough?", "Am I wet enough?".

This cognitive hypervigilance cuts off the feedback loop between the brain and the genitals.

Concerns about body image, the size of the genitals, or fear of causing pain or not satisfying a partner act as "short circuits" to arousal.

A man may be physically healthy, but if his mind is filled with doubts about his performance, the neurological signal to maintain erection is disrupted.