Menstrual cycles occur over about 1 month 28 to 32 days. At first, the menstrual periods may be irregular. A girl may go 2 months between periods, or may have two periods in 1 month. Over time, periods become more regular. Keeping track of when the period occurs and how long it lasts can help predict when the next menstrual period will occur.
After menstruation starts, the ovaries begin to produce and release eggs, which have been stored in the ovaries since birth. About every month after menstruation starts, an ovary releases an egg, called an ovum. The egg travels down a Fallopian tube, which connects the ovary to the womb. When the egg reaches the womb, the lining of the womb becomes thick with blood and fluid. This happens so that if the egg is fertilized, it can grow and develop in the lining to produce a baby.
It is important to remember that fertility comes before emotional maturity, and pregnancy can occur before an adolescent is prepared for parenthood.
If the egg does not meet with sperm from a male and is not fertilized, it dissolves. The thickened lining falls off and forms menstrual blood flow, which passes out of the body through the vagina. In between the menstrual periods, there may be a clear or whitish vaginal discharge. This is normal. During or just before each period, the girl may feel moody or emotional, and her body may feel puffy or swollen bloated. Premenstrual syndrome PMS may begin to develop, especially as the girl gets older.
In girls, puberty is usually finished by age Any increases in height after this age are uncommon. Although a girl has reached full physical maturity at this time, her educational and emotional maturity continue to grow. The first sign of puberty in boys is enlargement of both testicles. Afterward, boys will normally experience:. The testes constantly produce sperm.
Some sperm can be stored in a structure called the epididymis. Sometimes the stored sperm are released as part of the normal process to make room for new sperm. This can occur automatically during sleep nocturnal emissions or following masturbation or sexual intercourse.
Nocturnal emissions are a normal part of puberty. Adolescence is the time between the beginning of sexual maturation puberty and adulthood. For unknown reasons, the hypothalamus starts releasing pulses of gonadotropin-releasing hormone GnRH.
This hormone travels directly to the anterior pituitary gland and stimulates it to secrete hormones that target the gonads testes and ovaries. FSH stimulates the testes to produce sperm and follicles in the ovaries to mature and secrete estrogen.
LH stimulates the testes to secrete testosterone and the ovaries to secrete estrogen. Testosterone and estrogen, in turn, stimulate the development of primary and secondary sex characteristics and contribute to the spurt in physical growth.
In the United States, puberty in the biological male sex generally begins between the ages of 11 and 12 years and is usually over by the age of During puberty, the testes and scrotum start to increase in size first, followed by the penis.
At the same time that the penis is growing, the seminal vesicles, prostate, and bulbourethral glands are also growing and developing. Secondary sex characteristics, such as pubic hair, also develop. Additional physical changes that occur in boys during puberty include the appearance of facial and body hair and deepening of the voice as the vocal cords increase in size. The stages show the sequence in which the changes occur. Stage I represents the pre-pubertal stage at about age 11, and stage V represents the adult stage after the completion of puberty at about ages 16 to 18 years.
The first ejaculation generally occurs by the age of 13 years. Even this early in puberty, the semen may contain some sperm. Although full fertility may not be gained for another year or two, boys are generally fertile before they have completed their adolescent growth and achieved an adult appearance. Puberty in the biological female sexes typically begins a couple of years earlier than puberty in the biological males. In the United States, females begin puberty between the ages of nine and ten.
Visible, external changes begin first, including the growth and development of the breasts and pubic hair. About two years after breast development begins, the internal reproductive organs — including the uterus and vagina — start to grow and develop.
One of the most significant changes in females during puberty is menarche, which is the first menstrual period. It marks the beginning of menstruation. In the United States, menarche occurs at an average age of However, there is considerable variation in this age, with menarche at any age between eight and 16 considered normal.
The period of rapid growth in body size that occurs during puberty is called the adolescent growth spurt AGS. Both height and weight increase at a rate that is faster than at any time since early childhood. There are also significant changes in body composition and body proportions.
The adolescent growth spurt is controlled by hormones, including growth, thyroid, and sex hormones. The average boy and girl do not differ significantly from each other in growth rate before the AGS begins.
However, by the time they have attained their final adult height, the average female is about 13 cm 5. One reason is that the AGS occurs earlier in girls than in boys, so girls experience a shorter period of childhood growth, making them shorter, on average, when they begin the AGS in height.
Another reason is that the peak height velocity maximum rate of growth in height is lower for the average girl than it is for the average boy.
In boys, the AGS in height usually starts at about the age of 11 years. The peak height velocity in boys occurs at about age Growth in height in boys ceases by about age 18 or a bit later when the ends of the long bones finally ossify at the epiphyses, so additional growth in height is no longer possible. In girls, the AGS in height usually starts by the age of roughly 9. The peak height velocity in girls occurs at about age Growth in height in girls is completed by about 16 years if not earlier when the closure of the epiphyses prevents any additional growth in height.
The accelerated rate of growth during the AGS happens at different times for various parts of the body, but it occurs in the same predictable sequence for both sexes. Generally, the extremities — including the head, hands, and feet — experience rapid growth first, followed by the arms and legs, and then by the trunk and shoulders.
This non-uniform growth may make the adolescent body seem awkward and disproportionate until growth is completed. Growth in weight shows a similar spurt during adolescence as growth in height. Growth in weight occurs partly because of the growth in height, but growth in muscle, bone, and for girls especially body fat also contributes to the growth in weight. In boys, the AGS in weight lags behind the AGS in height by about three months, whereas in girls the lag time is about six months.
During the adolescent growth spurt, greater growth in muscles and bones occurs in males than females, and especially in the upper body. In males, the shoulders and chest broaden relative to the hips, whereas the reverse occurs in females: the pelvis and hips widen relative to the shoulders and chest. Male muscles may continue to grow and gain in strength for a year or more after growth in height is finished.
Females also experience a major increase in body fat during adolescence, especially in the breasts and hips. All of these sex differences in growth during puberty account for the sexual dimorphism in adult human body composition and shape.
Please note that the terms males and females refer to only biological sexes. A biological female may identify as a male and a biological male may identify as a female. Most children at this age fully understand their gender identity see Chapter Some start transitioning before puberty and never go through biological puberty. F'x F'x Also, it's worth noting that puberty as in sexual maturation can happen during childhood precocious puberty or at the end of adolescence late puberty.
F'x: I guess the definitions are sometimes a bit loose , even in scientific contexts. As you said, adolescence is more a "psychological" matter and puberty is more "physical". In the majority of cases, the periods largely overlap, so there is normally no issue. You missed an adjective: pubic. Other words with the same root also include pubes and pubis. Show 1 more comment.
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