Puberty

Puberty 

Definition

Puberty is the period of human development during which physical growth and sexual maturation occurs.

Description

Beginning as early as age eight in girls-and two years later, on average, in boys—the hypothalamus (part of the brain) signals hormonal change that stimulates the pituitary. In turn, the pituitary releases its own hormones called gonadotrophins that stimulate the gonads and adrenals. From these glands come a flood of sex hormones—androgens and testosterone in the male, estrogens and progestins in the female-that regulate the growth and function of the sex organs. It is interesting to note that the gonadotrophins are the same for males and females, but the sex hormones they induce are different.

In the United States, the first sign of puberty occurs on average at age 11 in girls, with menstruation and fertility following about two years later. Boys lag behind by about two years. Puberty may not begin until age 16 in boys and continue in a desultory fashion on past age 20. In contrast to puberty, adolescence is more of a social/cultural term referring to the interval between childhood and adulthood.

Diagnosis

Puberty has been divided into five Sexual Maturity Rating (SMR) stages by two doctors, W. Marshall and J. M. Tanner. These ratings are often referred to as Tanner Stages 1-5. Staging is based on pubic hair growth, on male genital development, and female breast development. Staging helps determine whether development is normal for a given age. Both sexes also grow axillary (arm pit) hair and pimples. Males develop muscle mass, a deeper voice, and facial hair. Females redistribute body fat. Along with the maturing of the sex organs, there is a pronounced growth spurt averaging 3-4 in (8-10 cm) and culminating in full adult stature. Puberty can be precocious (early) or delayed. It all depends upon the sex hormones.

Puberty falling outside the age limits considered normal for any given population should prompt a search for the cause. As health and nutrition have improved over the past few generations, there has been a gradual decrease in the average age for the normal onset of puberty.

Delayed or precocious puberty requires measurement of the several hormones involved to determine which are lacking or which are in excess. There are blood tests for each one. If a tumor is suspected, imaging of the suspect organ needs to be done with x rays, computed tomography scans (CT scans), or magnetic resonance imaging (MRI).

Treatment

Puberty is a period of great stress, both physically and emotionally. The psychological changes and challenges of puberty are made infinitely greater if its timing is off.

In precocious puberty, the offending gland or tumor may require surgical attention, although there are several drugs now that counteract hormone effects. If delayed, puberty can be stimulated with the correct hormones. Treatment should not be delayed because necessary bone growth is also affected.

Prognosis

Properly administered hormones can restore the normal growth pattern.

Resources

Books

Fauci, Anthony S., et al., editors. Harrison's Principles of Internal Medicine. New York: McGraw-Hill, 1997.

Key terms

Adrenals — Glands on top of the kidneys that produce four different types of hormones.

Computed tomography scan (CT) — A method of creating images of internal organs using x rays.

Embryo — The life in the womb during the first two months.

Gonads — Glands that make sex hormones and reproductive cells-testes in the male, ovaries in the female.

Hormone — A chemical produced in one place that has an effect somewhere else in the body.

Hypothalamus — Part of the brain located deep in the center of the skull and just above the pituitary.

Magnetic resonance imaging (MRI) — A method of creating images of internal organs. Magnetic resonance imaging (MRI) uses magnet fields and radio-frequency signals.

Pituitary — The "master gland" of the body, controlling many of the others by releasing stimulating hormones.

Syndrome — A collection of abnormalities that occur often enough to suggest they have a common cause.

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puberty /pu·ber·ty/ (pu´ber-te) the period during which the secondary sex characters begin to develop and the capability of sexual reproduction is attained.pu´beralpu´bertal

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central precocious puberty  precocious puberty due to premature hypothalamic-pituitary-gonadal maturation; it is always isosexual and involves not only development of secondary sex characters but also development of the gonads. Increases in height and weight and osseous maturation are accelerated, and early closing of the epiphyses leads to short stature.

precocious puberty  the onset of puberty at an earlier age than normal, defined as before age 8 in girls and 9 in boys; it is usually hormonal, but occasionally occurs in otherwise normal children.

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pu·ber·ty (pybr-t)

n.

The stage of adolescence in which an individual becomes physiologically capable of sexual reproduction.

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puberty,

n the period of development in which the body becomes physically capable of reproduction, distinguished by the maturity of the gonads and appearance of secondary sexual characteristics.

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puberty (pū´burtē),

n the age at which the reproductive system becomes functional, with concurrent development of secondary sex characteristics. Marked by increased estrogenic activity in the female and rise of androgenic activity in the male.

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puberty

the time at which reproduction by an individual animal becomes possible for the first time; a term used infrequently in veterinary medicine but there is no other word which can substitute for it.

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delayed puberty

varies widely between species and between breeds; negatively influenced by undernutrition and obesity.