What is an Impotence? Erectile Dysfunction Concept
By Elaine Waller, PharmD / Last Updated:
Reviewed by Eli Coleman, PhD
Erectile Dysfunction (ED), clinically defined as the inability to achieve or maintain an erection sufficient for satisfactory sexual intercourse, can be a deeply distressing experience for men with impotence. While the intimacy of a partner may stimulate desire, the physiological response, specifically the penile rigidity necessary for coitus, may be absent. This inability can lead to significant emotional distress and relationship challenges, as successful conception often relies on the ability to engage in penetrative sexual intercourse.
The term "Erectile Dysfunction" has replaced the older term "impotence," derived from the Latin "impotentia coeundi," which literally translates to the inability to engage in coitus. ED affects a significant portion of the male population, with studies indicating that at least 50% of men experience some degree of erectile difficulty at some point in their lives. This prevalence highlights the importance of understanding the underlying physiological mechanisms and potential contributing factors.
Physiology of Erection
Penile erection is a complex process governed by two primary mechanisms: reflexogenic and psychogenic. Reflexogenic erections occur due to tactile stimulation of the penis, while psychogenic erections are triggered by visual, auditory, or cognitive stimuli, often involving the limbic system and the hypothalamus. Both mechanisms require an intact and functioning nervous system, particularly the parasympathetic nerves originating from the sacral spinal cord.
The anatomy of the penis plays a crucial role in the erectile process. The corpora cavernosa, two cylindrical chambers within the penis, are composed of spongy tissue known as the corpus spongiosum. Upon sexual stimulation, nitric oxide (NO) is released from the endothelium and nerve endings. NO activates guanylate cyclase, leading to an increase in cyclic guanosine monophosphate (cGMP). cGMP causes relaxation of the smooth muscle within the corpora cavernosa, allowing increased blood flow into the penis. This influx of blood, coupled with the veno-occlusive mechanism that restricts venous outflow, results in engorgement and rigidity of the penis, achieving an erection. Any disruption in this intricate cascade of events, whether vascular, neurological, or hormonal, can contribute to the development of ED.
Term Explanations
- Erectile Dysfunction (ED): The medical term for the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual intercourse.
- Coitus: Sexual intercourse, specifically referring to the act of penile penetration of the vagina.
- Impotence: An older, less precise term for erectile dysfunction.
- Impotentia coeundi: The Latin term meaning "inability to engage in coitus," from which the word "impotence" is derived.
- Reflexogenic erection: An erection triggered by direct physical stimulation of the penis.
- Psychogenic erection: An erection triggered by mental or emotional stimuli, such as thoughts, fantasies, or sensory input.
- Limbic system: A set of brain structures involved in emotion, motivation, and memory, playing a role in sexual arousal.
- Hypothalamus: A region of the brain that controls many bodily functions, including hormone release and sexual behavior.
- Parasympathetic nervous system: A branch of the autonomic nervous system responsible for "rest and digest" functions, including penile erection.
- Sacral spinal cord: The lower part of the spinal cord from which nerves controlling pelvic organs, including the penis, originate.
- Corpora cavernosa: Two cylindrical chambers within the penis that fill with blood during an erection.
- Corpus spongiosum: Spongy tissue that fills the corpora cavernosa and the glans penis.
- Nitric oxide (NO): A signaling molecule that plays a key role in vasodilation, including the relaxation of smooth muscle in the corpora cavernosa.
- Endothelium: The inner lining of blood vessels.
- Guanylate cyclase: An enzyme that catalyzes the formation of cyclic GMP.
- Cyclic guanosine monophosphate (cGMP): A signaling molecule that mediates smooth muscle relaxation and vasodilation.
- Veno-occlusive mechanism: The process by which veins in the penis are compressed during an erection, preventing blood from flowing out and maintaining rigidity.
- Vascular: Relating to blood vessels and blood flow.
- Neurological: Relating to the nervous system.
- Hormonal: Relating to hormones and the endocrine system.
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Author
Elaine Waller, PharmD
Dr. Elaine Waller has substantial experience in domestic and international regulatory affairs, and in clinical research. Vice President of Regulatory Affairs and Quality Assurance. Prior to joining Sonus Pharmaceuticals in July 2003, she was Chief Operating Officer at Radiant Research, a clinical site management organization. Dr. Waller's previous experience includes senior positions in regulatory affairs and clinical research at Hoechst Marion Roussel and Marion Merrell Dow. She began her career in academia at the University of Texas at Austin where she held teaching positions in both graduate and undergraduate pharmacy education and was Assistant Director of Clinical Research at the Drug Dynamics Institute. Dr. Waller received a B.S. in Pharmacy and a Doctor of Pharmacy from the University of Missouri - Kansas City, and an M.B.A. from Rockhurst University.
