Penis

Definition

The penis is the male external reproductive organ, responsible for delivering sperm to the female reproductive tract during mating. It plays a crucial role in sexual reproduction, containing erectile tissue that allows for erection and the expulsion of semen. The penis is also involved in urination, serving as a conduit for urine to exit the body.

5 Must Know Facts For Your Next Test

1. The penis consists of three main parts: the root, the body (shaft), and the glans (tip).
2. During sexual arousal, blood fills the erectile tissues of the penis, causing it to enlarge and become rigid.
3. The penis contains two types of erectile tissue: corpora cavernosa and corpus spongiosum, which help achieve and maintain an erection.
4. Erections can be triggered by various stimuli, including physical sensations, thoughts, or visual cues.
5. The average size of an erect human penis varies widely but is generally considered to be between 5 to 6 inches in length.

Review Questions

• How does the structure of the penis facilitate its functions in both reproduction and urination?
  • The penis is uniquely structured to serve dual purposes: reproduction and urination. It has three main parts—the root, body, and glans—that work together during sexual arousal to achieve an erection. The erectile tissues allow for increased blood flow, enabling penetration during mating, while the urethra runs through the penis, allowing urine to exit from the bladder. This anatomical design ensures that both functions can occur efficiently and effectively.
• Discuss the physiological processes involved in achieving an erection and their significance for male reproductive health.
  • An erection is primarily achieved through a complex interplay of psychological and physiological factors. When sexually aroused, nerve signals stimulate blood vessels in the penis to relax, leading to increased blood flow into the erectile tissues. This engorgement causes the penis to enlarge and stiffen. Maintaining healthy erectile function is essential for reproductive health, as it directly affects a man's ability to engage in sexual intercourse and thus impacts fertility.
• Evaluate how hormonal regulation affects penile function and its implications for male fertility.
  • Hormonal regulation plays a crucial role in penile function, particularly through testosterone. This hormone influences not only the development of the penis but also maintains libido and erectile function throughout a man's life. Low levels of testosterone can lead to diminished sexual desire, erectile dysfunction, and ultimately affect fertility by reducing sperm production. Understanding these hormonal influences is vital for addressing male reproductive health issues and fostering successful outcomes in sexual reproduction.

Related terms

Erection: The physiological process by which the penis becomes enlarged and firm due to increased blood flow to the erectile tissues.

Semen: The fluid that contains sperm and is expelled during ejaculation, playing a key role in fertilization.

Testosterone: The primary male sex hormone that influences the development and function of male reproductive organs, including the penis.