Think of an erection like inflating a balloon. Your brain needs to send a signal (sexual stimulation) to release chemicals that relax the blood vessels in the penis, allowing them to fill with blood (inflate). In many men with erectile dysfunction (ED), this process is hindered because an enzyme called PDE5 destroys a key chemical needed for relaxation too quickly.
Cialis is a PDE5 inhibitor. Its job is to block that enzyme. By blocking PDE5, it allows the natural chemicals released during sexual stimulation to build up and work longer, keeping the blood vessels relaxed and allowing for a firm erection.
Crucially, Cialis does not cause an erection on its own. It requires sexual arousal to start the natural process; it just helps that process work better.
The Detailed Mechanism: Step-by-Step
To understand how Cialis works, it helps to understand the natural process of an erection.
The Natural Process (Without Cialis)
1.Sexual Stimulation: Your brain receives a signal (sight, touch, thought) and sends a message via nerves to the penis.
2.Release of Nitric Oxide: These nerve endings release a chemical called nitric oxide (NO) into the erectile tissue of the penis.
3.Production of cGMP: Nitric oxide triggers an enzyme to produce another chemical called cyclic guanosine monophosphate (cGMP) .
4.Relaxation and Blood Flow: cGMP is the key that unlocks the door. It causes the smooth muscles in the walls of the arteries in the penis to relax. This relaxation widens the arteries, dramatically increasing blood flow into the penis. The incoming blood compresses the veins that normally drain blood out, trapping it inside. This is the erection.
5.The Natural Brake (PDE5): Your body has a natural "off switch" to prevent an erection from lasting forever. An enzyme called phosphodiesterase type 5 (PDE5) is constantly present. Its job is to break down cGMP. As cGMP is broken down, the smooth muscles constrict again, the arteries narrow, blood flows out, and the erection subsides.
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