Physiology of normal erectile function and Viagra
Penile erection is the most obvious feature of the male body’s response to sexual excitement. It is a complex neurovascular response, influenced by cognitive inputs and facilitated by testosterone [12]. Other features of that response include increases in skin temperature, blood pressure, hear t and breathing rates, facial and bodily flushing, dilation of the pupils, and nipple erection. There are also changes in skin’s sensitivity to touch. 
These changes are similar in both men and women. Erection response to sexual interest is the result of interplay between tactile, visual , auditory, and olfactory signals, combined with cognitive inputs, such as fantasy and memory. These stimulimay be erectogenic or erectolytic, pleasant or unpleasant , and are integrated in specific nuclei within the midbrain. This balance between stimuli may result in percentile signaling transmitted via the spinal cord, pelvic nerves and cavernous nerves running either side of the prostate gland, before finally terminating around the vascular smooth muscle of the corpora cavernosa. Erections can also occur in the absence of sexual stimulation. Most men will get spontaneous erections in their sleep, imrelated to sexual thoughts or dreams. Myviagrainaustralia.com get viagra online now.
Contrary to popular belief, they are not caused by having a full bladder, but probably by unconscious and involuntary changes in the electrical activity of the brain. Men can also get ‘reflex’ erections, due to activity of sensory- motor linkages within the spinal cord. These are common in men with multiple sclerosis and some types of spinal cord injury. Erection is a complex series of integrated vascular events culminating in the accumulation of blood under pressure and end’organ rigidity. Fundamentally involved in the intrapenile response are the paired corpus cavernosa that contain the erectile components and are surrounded by a thick fibroelastic sheath, the tunica albuginea.