First Lesson about PENIS

PENIS

Penis (from the Latin meaning "tail", he said the same root with the phallus, which has the same meaning) is the male genitalia. [1] The penis is an external organ, because it is outside the living body.

Use the term "penis" virtually always in the context of biology or medicine. The term "falus" (the phallus) is used in cultural context, particularly on the depiction of a tense penis (erection). Linga (or lingam) is one of the depiction falus. In religious literature (Islam), more commonly used word penis. Because in many organs of society is considered taboo to discuss openly, many euphemisms used to express it, such as "bird", "banana", dick, or cock (English).

The function of the penis in biology is as a means of disposal (an organ of excretion) metabolism remains liquid (urination) and as a tool for reproduction. Real penis is owned by mammals and become the main character of the male sex.

Organs with similar functions of other division members of the animal is sometimes called a penis, although technically not as if the penis in mammals.

Animals Penis
Animal penis is usually proportional to body size, but there is great variation in size between species, both its length and diameter, however, almost always a tube shape. For example, an adult gorilla penis erection middle reaches 4 cm, while that of chimpanzees penis size smaller body length doubles. Relatively large human penis sekerabat proportions than other primates.

Kangaroos, as well as various other marsupials, have a penis with a forked tip. With the smallest vertebrate penis Shrew, whose length when erect is only half a centimeter. Echidna has a penis with four tip, but only two corners of that function. [2]

Reptiles do not have a true penis because only a small bulge and not visible from the outside, so-called hemipenis ("half-penises").

Poultry has only a small bulge in the cloaca, are similar to those of reptiles. Manila duck (stuck) is known to have a typical penis and the only birds that have a clear reproductive organs

Human Penis
Human penis is part of the male reproductive system (male) as well as part of the excretion system. In addition to the penis, the male reproductive organs include the epididymis (testicles) are protected in the scrotum (testicles or scrotal sac), plus a few gland and duct.

Although the human penis has its function and origin (ontogeny) is similar to other mammals, it has a peculiarity. By comparison, the proportion of the human penis is larger than any other mammal. Human penis has no protective skin to hide in when the "rest". In addition, the human penis has no baculum, or penis bone, so as to penetrate into the vagina, the penis erection relies entirely on the blood supply into the sacs (corpora) which is in the shaft of the penis.

Parts and structures
Human penis is composed of two main parts, namely the base / root (radix) and body (corpus). Base of the penis lies in the body, consisting of bubbles of the penis (penile bulb) and a pair of penile crus on both sides. Surface of the skin which protects the base of the penis usually have a pubic hair. Body surface of the penis has two sides: the dorsal (the one seen from the front if the penis is "rest") and the ventral or urethral (inward / testis).

Penile body structure supported by three bags: a pair of corpora and corpus spongiosus cavernosus between them, located on the ventral side and protects the urinary tract (urethra). At the end of the rod-shaped glans penis there is somewhat tapered at the ends, which facilitates penetration during sexual relations.

The urethra is the channel for the semen (sperm or seminal fluid) as well as urine (urine or urine). The tip of the urethra, which appeared on the glans penis called the meatus. Urine through the urethra when the valve at the bottom of the bladder is opened. Semen through the urethra during ejaculation. Sprays on ejaculation is not controlled by the urethra, but by the muscles that surround the base of the penis.

In the ventral part of the shaft of the penis looks raphe, a line of strokes from the back of the glans penis into the anus through the scrotum. Raphe on female develop into the vaginal opening.

Development, growth and size
Developing penis during sex determination in the womb. Like the ovaries (egg bladder), both evolved from the gonads, which develops as a thickening layer on the peritoneum mesotel. Own peritoneum develops from mesoderm. Gender differences began to appear after a seven-week-old embryo.

At birth, the penis has been well developed. At some developmental disorders can occur or occurs hidden penis hermafroditisme, namely sex organs are formed every second.

In normal growth, penis and testicles sac begin to experience growth during puberty (legally Baligh in Islamic religious terms). The hormone testosterone plays a role in this development. It is this process that will determine the size of the penis. Based on observations of thousands of examples of men aged 17-18 years found no difference in average length of the penis between the ages of 17 and 19 years, so it can be concluded that the development of the penis stops at around age 17 years or even earlier. [3]