Erection: How does it work?

An erection is the result of a complex interplay of neural, psychological, hormonal and vascular (blood vessels in question) factors. In the flaccid state the penis has only a low arterial blood supply. During erection in the helicine arteries open (see structure of the penis) and the blood flow into the sinusoids. Pressures to achieve up to 10 times the arterial blood pressure (1200 mmHg). The possibility of such a pressure increase is the result of the interplay between muscular contraction and relaxation.

The smooth (involuntary influenced) by muscle cells in the cavities of the corpora cavernosa are contracted in the non-erect state (tense). They leave it to the blood hardly a way to take in the cavernous space. At the same time the blood is discharged freely through the veins, so that the penis in a flaccid state, not limp.

Dissolves the tension of the smooth muscle cells, it comes to an erection, because the arterial blood is pumped freely into the sinusoids. The sinusoids can absorb 40 times the amount of blood than in the flaccid state. To open the shutters of the helicine arteries. By increasing blood flow creates pressure the veins, which are so tied. This will only slow down the blood again derived from the corpora cavernosa. Thus, the erectile tissue can be very hard. When cavernosa urethras the blood flows through the dense venous plexus decreases significantly faster. So the cavernosa urethras is not as jam-packed with blood and therefore much softer. This is necessary so that the sperm can be transported via the urethra and is expelled during ejaculation through the urethral opening.


The muscular relaxation in the corpora cavernosa is crucial for the erection
Crucial for the erection of the penis and relaxation of the muscular tension in the corpora cavernosa. The reaction begins with a stimulus. The nerve impulses erection are controlled by the parasympathetic path of the autonomic nervous system. The whack of the penis is on the other hand is passed over the sympathetic division (see structure of the nervous system). Up to the muscle cell, the signal is passed neuro. Within the cell, it must be translated into the language of complex cell, which consists of biochemical reactions. The electrical signal is translated into a chemical messenger (transmitter), which sets a cascade within the cell into the corridor.


Nitric encounters, stimulated by a nerve impulse to the chemical cascade
One of these is the transmitter nitric oxide (NO). It is the trigger that - similar to a chain reaction - execute many chemical processes within the cell that ultimately result in a relaxation of smooth muscle cells. By the relaxation of smooth muscle cells, blood can get into the sinusoids and it comes to erection.


PDE5 inhibitors are potent drugs that lead to relaxation of smooth muscle cells and thus allow an erection
NO leads to guanylate cyclase (GTP) is distributed. GTP is transformed into cyclic GMP (cGMP). cGMP in turn activates the protein kinase G, which in turn stimulates the proteins within the cell, which then leads to the relaxation of smooth muscle cell. Crucial for the reaction is the cGMP. A high proportion of cGMP enhances the erection. The concentration of cGMP is regulated by the substance of phosphodiesterase 5 (PDE5). PDE5 leads to inactivation of cGMP. In the drug treatment of erectile dysfunction of this mechanism is affected. PDE5 inhibitors cause a high concentration of cGMP and thus facilitate the erection.