The ejaculatory reflex is a neurophysiological process that results in the expulsion of semen from the male urethra during sexual activity. It is the final stage of intercourse in male mammals and comprises two coordinated phases: emission and expulsion.
Phases of the Ejaculatory Reflex
The ejaculatory reflex is not a single event but rather a sequence of physiological changes:
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Emission Phase: This is the first phase and involves the movement of seminal fluid from various reproductive organs into the prostatic urethra. This includes:
- Secretions from the vas deferens (containing sperm).
- Secretions from the seminal vesicles (contributing to the fluid volume and nutrients).
- Secretions from the prostate gland (adding enzymes and fluids that protect sperm).
- Secretions from the Cowper's gland (pre-ejaculate, which lubricates the urethra and neutralizes acidity).
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Expulsion Phase: This phase involves forceful contractions of the pelvic floor muscles and the urethral bulbospongiosus muscle. These contractions propel the semen out of the urethra. Simultaneously, the bladder neck closes to prevent retrograde ejaculation (semen entering the bladder).
Neural Control
The ejaculatory reflex is primarily controlled by the autonomic nervous system.
- Sympathetic Nervous System: Plays a crucial role in the emission phase.
- Parasympathetic Nervous System: Contributes to some aspects of the emission phase.
- Somatic Nervous System: Is primarily responsible for the expulsion phase, controlling the muscular contractions.
The reflex involves a complex interplay of sensory input from the genitals, spinal cord pathways, and brain centers. Afferent signals are transmitted to the spinal cord, which then relays signals to the brain. Efferent signals are then sent back from the brain and spinal cord to the reproductive organs and muscles, initiating and coordinating the emission and expulsion phases.
Dysfunction
Disorders related to the ejaculatory reflex include:
- Premature Ejaculation: Ejaculation that occurs sooner than desired.
- Delayed Ejaculation: Difficulty or inability to ejaculate.
- Retrograde Ejaculation: Semen entering the bladder instead of being expelled from the penis.
- Anejaculation: Inability to ejaculate.
These conditions can stem from psychological factors, nerve damage, medication side effects, or hormonal imbalances.
