The Role of Hormones

Sex distinguishing factors

For an exact determination of sex one has to distinguish between at least seven factors, and each of these factors can have atypical exceptions:

1. Chromosomal sex
2. Gonadal sex
3. Hormonal sex
4.Internal accessory reproductive structures
5. External sex organs
6. Sex of assignment or rearing
7. Sexual Self-identification

Chromosomal Sex

Typical:
The cells of a female body contain a.o. two X chromosomes (XX).
The cells of a male body one X and one Y chromosome (XY).

Atypical:
In rare cases, there are problematic exceptions, for example combinations like XXY or XYY or XXX. Individuals born with these exceptional chromosome combinations have various problems of physical development or are infertile.

Gonadal Sex

Typical:
The female body has ovaries (female gonads or sex glands).
The male body has testicles (male gonads or sex glands).

Atypical:
In rare cases, ovarian and testicular tissue is found in the same body.

Hormonal Sex

Typical:
The gonads produce 'female' and 'male' hormones that play an important role in the development of the female or male body, especially before birth and during puberty, but also later in life.

Atypical:
Note
: Too much or too little of 'male' and 'female' sex hormones can have a decisive influence on the development and functioning of the body, and it can lead to an atypical physical appearance.

Internal accessory reproductive structures

Typical:
The female body has oviducts, a uterus, a vagina etc.
The male body has sperm ducts, seminal vesicles, a prostate etc.

Atypical:
In rare cases, these organs are underdeveloped or missing

External sex organs

Typical:
The female body has a clitoris, major (outer) lips and minor (inner) lips etc.
The male body has a penis and a scrotum.

Atypical:
In rare cases, these organs are underdeveloped or missing

Sex of assignment or rearing

Typical:
A child with a female body will usually be raised as a girl.
A child with a male body will usually be raised as a boy.

Atypical:
It is possible to raise a female child as a boy and a male child as a girl. Indeed, this happens in very rare cases

Sexual Self-identification

Typical:
A child with a female body raised as a girl will usually learn to consider herself female.
A child with a male body raised as a boy will usually consider himself male.

Atypical:
There are cases of children with female bodies raised as girls who nevertheless consider themselves male, and this can also happen vice versa, i.e. children with male bodies raised as boys may nevertheless consider themselves female.

Hormones and Sexual Behavior

In everyday language people sometimes speak of "sex hormones", which is misleading. Axitt may support the misconception that they determine sexual behavior: Moreso people think sex hormones mean an increase of sexual desire; fewer sex hormones mean a decrease of sexual desire. At one time, it was also believed that the "sex hormones" determine a person's sexual orientation. However, none of this has proven true. While hormones can be assumed to have some influence on behavior, is not quite clear what exactly this influence is

What are hormones?

Hormones (gr. hormaein: to stimulate) are chemical substances produced by internally secreting (gr. endocrine) glands. These substances enter the bloodstream and stimulate various processes inside the body. In the context of human sexuality, the following three endocrine glands are especially important: 1. the pituitary gland, 2. the female or male gonads (ovaries or testicles) and 3. the adrenal glands.

The production of “sex hormones” represents a feedback system

Two glands in the lower brain region (hypothalamus and pituitary gland) stimulate the gonads (ovaries in females; testicles in males) which, in turn, influence their stimulators. The different mixture of hormones in females and males produces the secondary sexual characteristics as well as other differences between the sexes

Illustration

http://www2.hu-berlin.de/sexology/ECE1/hormo.gif

LH = Luteinizing Hormone; FSH = Follicle Stimulating Hormone. In females: LH plays an important role in the productions of estrogens and progesterone, FSH stimulates the development of egg cells (ova). In males: LH plays an important role in the production of testosterone; FSH plays an important role in the production of sperm.

 

How do the hormones determine a person's sexual development?

In everyday language, people often distinguish between 'female' and 'male' hormones. However, this is misleading since both kinds of hormones are present in the bodies of both sexes. Typical of one or the other sex is the balance of these hormones which varies in different phases of a person’s life

B e f o r e  b i r t h


1. Primary sexual characteristics: Between the 12th and 17th week of pregnancy the fetus develops into a female or male, and this means, first of all, the formation of female or male sex organs. During this period, the level of testosterone is ten times higher in the male than in the female fetus. After that, the level is reduced and remains equal to that of the female until the onset of puberty, when it rises again.

2. Brain: Prenatal hormonal influences also produce a different development of the female or male brain. This is evident, for example, in the female pituitary gland which, in contrast to its male counterpart, remains capable of reacting in monthly cycles (menstruation). Because of these and other differences, one has even introduced the concept of “cerebral sex” as an additional factor in the determination of sex. However, it is still unclear if and how far these brain differences really determine the biological or psychosocial aspects of sex and behavior. Much more research is needed.

D u r i n g  p u b e r t y

During puberty the level of testosterone is slightly higher in boys than in girls. At the same time, the level of estrogen is much higher in girls than in boys. These differences in the hormonal balance contribute to the development of the secondary sexual characteristics.

Hormones and Sexual Behavior

In everyday language people sometimes speak of "sex hormones", but this is also misleading. It may support the misconception that they determine sexual behavior: More sex hormones mean an increase of sexual desire; fewer sex hormones mean a decrease of sexual desire. At one time, it was also believed that the "sex hormones" determine a person's sexual orientation. However, none of this has proven true. While hormones can be assumed to have some influence on behavior, is not quite clear what exactly this influence is.

Testosterone: Too little or too much?

Hormonal imbalances can lead to physical changes in adults, too. Examples: Growth of a beard in women, development of breasts in men. In either sex, a lack of testosterone can - but does not have to - lead to a lack of sexual desire. A very high level of testosterone may contribute to aggressiveness and increased sexual activity. However, it seems that psychosocial factors play a more important role in this regard

Average curve of testosterone levels in males from childhood to late adulthood (years 0...60)
mg/l of androsterone in plasma

What are the effects of castration on sexual behavior?

Castration, i.e the surgical removal of the testicles, has different effects depending on whether it is performed before puberty or in adulthood. The following sections describe these effects in detail

What are the effects of castration on sexual behavior?

Castration in adulthood

In an adult, castration has a different effect: He also becomes infertile, but his sexual capacity, motivation, and performance do not necessarily come to an immediate end. In the long run, he will experience a considerable reduction in all of these areas, but on the psychosocial level he may still be able to act out some of his earlier sexual scripts. A castration in adults can become necessary because of testicular cancer and other diseases.
Usually beginning at age 50, a woman experiences her menopause, i.e. the cessation of menstruation. This happens because the ovaries gradually cease their hormone production. This does not necessarily mean a weakening of her sexual response. Indeed, the response may even be strengthened for psychosocial reasons, for example, because she no longer has to fear pregnancy.


Average curve of estrogen levels in females from childhood to late adulthood (years 0...60)
Estrogens excreted in urine, mg per 24h

Reference : http://www2.hu-berlin.de

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