
Penises come in different sizes, shapes, and colors. These traits are hereditary, like eye color or foot size, and there's nothing you can do to change them. Despite what you may hear or read, no special exercises, supplements, or diets will speed up the development process or change a guy's size. Also, like his feet, a guy's penis may appear smaller to him just because the perspective is different when he's looking down. And there's a lot less difference in penis size between guys when they get an erection than when their penises are relaxed.
In addition to size, guys also wonder about other aspects of how their penises look, such as whether the skin covering the penis is normal or if it's OK for a guy's penis to hang to the left or right (it is!). If you're concerned about how your penis looks, ask your doctor. Guys who are reaching puberty should have regular testicular exams, so that's a good time to ask your doctor any questions.

How is a penile erection sustained?
Penile erection is sustained by holding back and trapping the blood in the penis. The enlarged penis compresses the blood vessels that drain the blood out of penis to the tunica albuginea. But when an enzyme called phosphodiesterase type 5 (PDE5) becomes active, the cGMP level falls, followed by corpora cavernosa muscle contraction. As a result the blood in-flow is stopped and the veins drain the blood out of the penis and the erection goes away.
What is impotence or erectile dysfunction?
The inability to attain and maintain a penile erection required for a successful penetrative sexual intercourse is called erectile dysfunction. The level of erectile dysfunction may differ from an individual to the other as erectile dysfunction can be mild, moderate or severe.
Erectile dysfunction is not related to low sexual drive or problems with ejaculation. Erectile dysfunction is not a disease; it is a sexual condition with one or more serious physical or mental factors behind its cause.
What are the causes of erectile dysfunction?
Ageing, hypertension or high blood pressure, diabetes mellitus, substance abuse, low testosterone levels, cigarette smoking, nerve or spinal cord damage, cardiovascular diseases, medications and depression and anxiety are the main physical and psychological causes of erectile dysfunction.
These diseases and conditions can disrupt the normal functioning of the following body systems and organs that are responsible for a normal erection:
1. Nervous system
2. Overall arteries, more importantly arteries in corpora cavernosa area
3. corpora cavernosa area muscles & tissues and
4. Nitric oxide level in penis.
Can erectile dysfunction be cured?
ED can be treated and controlled effectively, but not exactly cured to the root. New prescription drugs like Levitra are available now to make the victim of ED answer naturally to sexual excitement.