The corpus cavernosum refers to the two cylindrical chambers that make up the majority of the penis. These spongy, erectile tissues fill with blood during sexual arousal, causing the penis to become erect and increase in size and rigidity.
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The corpus cavernosum is composed of spongy, vascular tissue that can expand to hold increased blood volume during an erection.
Smooth muscle fibers within the corpus cavernosum relax to allow for vasodilation and increased blood flow when sexually aroused.
Impairment of blood flow or nerve function to the corpus cavernosum can lead to erectile dysfunction.
Phosphodiesterase type 5 (PDE5) inhibitors, such as sildenafil (Viagra), work by enhancing nitric oxide signaling to promote vasodilation in the corpus cavernosum.
The corpus cavernosum is surrounded by a tough, fibrous sheath called the tunica albuginea, which provides structural support during an erection.
Review Questions
Explain the role of the corpus cavernosum in the physiology of penile erection.
The corpus cavernosum is the primary erectile tissue of the penis. During sexual arousal, the smooth muscle fibers within the corpus cavernosum relax, allowing increased blood flow to fill and expand the spongy tissue. This engorgement of blood causes the penis to become erect and increase in size and rigidity. The corpus cavernosum works in conjunction with the corpus spongiosum to facilitate this process, which is mediated by the release of nitric oxide and other signaling molecules.
Describe how phosphodiesterase type 5 (PDE5) inhibitors, such as sildenafil (Viagra), affect the corpus cavernosum to treat erectile dysfunction.
PDE5 inhibitors work by blocking the enzyme phosphodiesterase type 5, which normally breaks down cyclic guanosine monophosphate (cGMP). cGMP is a key signaling molecule that promotes vasodilation and smooth muscle relaxation in the corpus cavernosum. By inhibiting PDE5, PDE5 inhibitors allow cGMP levels to remain elevated, enhancing nitric oxide signaling and facilitating increased blood flow to the corpus cavernosum. This, in turn, leads to improved erectile function and the ability to achieve and maintain an erection.
Analyze how impairment of the corpus cavernosum, either through vascular or neurological mechanisms, can contribute to the development of erectile dysfunction.
Proper function of the corpus cavernosum is essential for normal erectile physiology. Conditions that impair blood flow to the corpus cavernosum, such as atherosclerosis or diabetes, can limit the ability of the tissue to become engorged with blood and achieve an erect state. Similarly, damage to the cavernous nerves that innervate the corpus cavernosum, often seen in conditions like prostate cancer treatment or spinal cord injury, can disrupt the neurological signaling required to trigger vasodilation and smooth muscle relaxation. In both cases, the impairment of corpus cavernosum function leads to the inability to attain or maintain an erection, resulting in erectile dysfunction.
The corpus spongiosum is the third cylindrical chamber in the penis, located below the corpora cavernosa. It surrounds the urethra and becomes engorged with blood during an erection.
Cavernous Nerves: The cavernous nerves are responsible for transmitting signals from the spinal cord to the corpus cavernosum, triggering the vasodilation and engorgement that leads to penile erection.
Nitric oxide is a key signaling molecule that triggers the relaxation of smooth muscle in the corpus cavernosum, allowing blood to flow in and cause an erection.