Hemodynamics of Erection and Viagra Australia

July 4, 2014 admin Erectile Disfunction

Flaccid State and Viagra Australia

The flaccid state of the penis is characterized by blood flow sufficient to meet nutritional and other physiologic needs, but insufficient for penile erection. During this state, sustained partial contraction of smooth muscle cells in the walls of arteries, arterioles, and in the corporal trabeculae is essential for the limitation of blood flow. The molecular mechanisms leading to this tonic smooth muscle contraction are discussed below.

Tumescence and Erection

With sexual stimulation and subsequent release of proerectile mediators onto corporal smooth muscle the erectile response is initiated. Within the corpora cavernosa there is dilation of arteries and arterioles and thus increased inflowing blood. The trabecular smooth muscle additionally relaxes allowing corporal sinusoids to expand as they become engorged with blood. This cavernosal expansion begins to compress the subtunical venules decreasing venous outflow. With further engorgement, the tunica is stretched occluding the emissary veins between the two tunical layers leading to minimal venous outflow. This leads to an increase in intracavernosal pressure to approximately 100 mmHg that raises the penis to the fully erect position. Cialis Australia online – cheap tadalafil medications shop.

During heightened sexual activity, the penis enters the rigid-erection phase. The ischiocavernous muscles contract, as a result of the bulbocavernosus reflex, compressing the base of the corpora cavernosa leading to temporary cessa-tion of inflow and outflow of blood and increas-ing intracavernous pressures up to several hundred mmHg.

The corpus spongiosum and glans behave somewhat differently in tumescence and erection. Arterial flow increases in these locations just as in the cavernosa. Due to differences in the tunica albuginea, thin in the spongiosum and absent in the glans, venous occlusion is less in these locations. This leads to pressures in the spongiosum only one third to one half of that of the cavernosa. The glans and spongiosum thus act essentially as arteriovenous shunts during erection. Similar to the corpora cavernosa, during the rigid erection phase contraction of the ischiocavernosus and bulbocavernosus muscles compresses out-flowing veins leading to further pressure increase in the spongiosum and glans. The deep dorsal vein is compressed between the engorged cavernosa and Buck’s fascia contributing to rigidity of the glans.

Detumescence

With cessation of sexual stimulus and subsequent decrease in erection inducing neural activity, the erectile response ends and canadian pharmacy viagra. Antierectile neural input leads to vasoconstriction of penile arteries and contraction of the trabecular smooth muscle resulting in reduced arterial inflow and collapse of the trabeculae. With decreased arterial inflow and subsequent corporal decompression, occlusion of venous drainage subsides allowing efflux of corporal blood and return to flaccid state physiology.