Below is a three dimensional flythrough illustration of the erectile tissue of a penis. (It may take a few seconds to load). You can zoom in and out and spin the image around to view from any angle.
The Corpus Spongiosum erectile tissue extends to the glans of the penis. It is rich with sensitive nerve endings, especially at the exposed tip.
The clitoris is made from the same kind of tissue.
What causes an erection
Mental and/or physical stimulation causes the brain to trigger a hormonal response. This hormonal system causes nitric oxide to be released in areas of the body associated with blood supply to the penis. The nitric oxide sets off a process that allows the arteries to expand, thereby increasing blood supply to the Corpus Cavernosa and Spongiosum. This causes an erection. Another chemical called PDE5 is involved in reversing this action.
There are many reasons why an erection may be unreliable. These include the effects of aging, medical conditions, implications of surgery or trauma, hormone imbalance, obesity, drugs, anxiety, stress and relationship problems. It is important to rule out any medical reasons before further investigations because unreliable erection can be an early indication of heart and blood circulation problems.
Viagra (or Sildenafil) is an example of a class of drug called PDE5 inhibitors that won’t initiate, but can be very effective in assisting an erection by keeping the nitric oxide system active for longer. Other popular options are Cialis (Tadalafil) and Levitra (Vardenafil). These should not be taken without professional medical advice because of possible interactions with other prescribed medication.