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Erkek Cinsel Tepkisi: Ereksiyon ve Boşalma
Cinsel uyarım, fiziksel temas ve görsel veya işitsel ipuçları gibi çeşitli biçimler alabilir. Bu olduğunda, omuriliğin sakral kısmındaki parasempatik…
Cinsel uyaranlara yanıt olarak, parasempatik nöronlar, penisteki arteriyolleri genişleten nitrik oksit veya NO'nun lokal salınımını uyarır. Bu, erektil dokulara kan akışını arttırır - corpora cavernosa ve corpus spongiosum.
Erektil dokuları dolduran kan, kanın penisten çıkmasını önlemek için damarları sıkıştırır.
Sonuç olarak, penis tıkanır ve sertleşir, bu da ereksiyona yol açar.
Cinsel uyarılmanın kritik noktasında, bel bölgesindeki sempatik lifler tarafından koordine edilen bir omurga refleksi boşalmayı tetikler.
Bu refleks, epididim, vasa deferens, seminal veziküller ve prostat bezinin koordineli kasılmalarına neden olarak spermi prostat üretrasına iter.
Meni penise girdikten sonra, pelvik tabandaki bulbospongiosus ve ischiocavernosus gibi kaslar kasılır.
Kanalların, bezlerin ve kasların bu kasılmaları, boşalma adı verilen bir süreçte spermi üretradan dışarıya zorla dışarı atar.
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Q1: How does nitric oxide cause an erection?
Sexual stimulation activates parasympathetic neurons that release nitric oxide in the penis. Nitric oxide dilates the arterioles, increasing blood flow into the erectile tissues—the corpora cavernosa and corpus spongiosum. The blood filling these tissues compresses the veins, preventing blood from leaving and causing the penis to become engorged and rigid.
Q2: What role do the accessory glands play in ejaculation?
During ejaculation, a sympathetic reflex triggers coordinated contractions of the accessory glands of the male reproductive system, including the seminal vesicles and prostate gland. These contractions propel semen into the prostatic urethra in a process called emission, which precedes the forceful expulsion of semen from the body.
Q3: What is the difference between emission and ejaculation?
Emission occurs when sympathetic fibers in the lumbar spine trigger contractions of the epididymis, vasa deferens, seminal vesicles, and prostate, propelling semen into the prostatic urethra. Ejaculation follows when pelvic floor muscles like the bulbospongiosus and ischiocavernosus contract, forcefully expelling semen from the urethra to the exterior.
Q4: Which spinal nerves control the male sexual response?
Parasympathetic fibers in the sacral portion of the spinal cord initiate erection by stimulating nitric oxide release. Sympathetic fibers located in the lumbar region, typically at T12-L2, coordinate the reflex that triggers ejaculation through contractions of reproductive ducts and glands.
Q5: How do pelvic floor muscles contribute to ejaculation?
During ejaculation, pelvic floor muscles including the bulbospongiosus and ischiocavernosus contract forcefully around the urethra. These muscular contractions expel semen from the penis to the exterior, completing the ejaculatory process after semen has entered from the accessory ducts of the male reproductive system.
Q6: What prevents blood from leaving the penis during an erection?
As blood fills the erectile tissues—the corpora cavernosa and corpus spongiosum—it exerts pressure that compresses the veins in the penis. This compression prevents venous outflow, trapping blood within the erectile tissues and maintaining the rigid, engorged state characteristic of an erection.
Q7: What types of sexual stimuli trigger the parasympathetic reflex?
Sexual stimulation can take various forms, including physical touch and visual or auditory cues. Any of these stimuli activate the parasympathetic reflex in the sacral portion of the spinal cord, which initiates nitric oxide release and the cascade of physiological events leading to erection.