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You are reading an older version of this FlexBook® textbook: Human Biology Your Changing Body Teacher's Guide Go to the latest version.

4.1: Planning

Difficulty Level: At Grade Created by: CK-12

Key Ideas

• Sexual maturation involves two kinds of change-primary and secondary. Primary change affects reproductive organs. Secondary change affects characteristics that set girls apart from boys and the physically mature from the immature.
• Menarche is the key transitional step to woman-hood. However, it does not mark the beginning of puberty. Typically it is one of the later events, usually about two years after the beginning of breast development and after the peak of the growth spurt (avg. age = 12.8, normal range, 9-18). Menopause marks the end of a woman's reproductive years.
• Nocturnal emissions (wet dreams) or ejaculation with masturbation signal semen production.
• Heredity and environment, which includes both physical and social environment, determine not only our schedule of development, but also our lifelong health. Nutrition and health care have the greatest impact on our reproductive health.

Overview

This section deals with the maturation of the reproductive system during puberty. Students use graphs to see the average age and the normal range of development for boys and girls. The graphs show height spurt, the appearance of pubic hair, the development of breasts and menarche in girls, and the growth of the testes and the penis in boys. Through discussion groups students share their concerns over the changes they are facing. They try to learn what the changes during puberty are like for the opposite sex. Students also distinguish between those factors influencing development during puberty over which they have control, and those factors over which they have no control. Groups make suggestions for how to maximize healthy development.

Objectives

Students:

$\checkmark$ distinguish between primary and secondary sexual characteristics.

$\checkmark$ identify the normal time range for change in girls and boys during puberty.

$\checkmark$ read a graph.

$\checkmark$ construct a chart using data from the graph.

$\checkmark$ express their own concerns over the changes of puberty.

$\checkmark$ listen to the concerns of others.

$\checkmark$ identify factors in the physical and social environment that influence puberty.

Vocabulary

axillary hair, ejaculation, environment, genitals, larynx, masturbation, menarche, menopause, menstruation, nocturnal emissions, ovaries, penis, physical environment, pubic hair, scrotum, secondary sexual characteristics, semen, sperm, social environment, testes

Student Materials

Activity 3-1: Changes in Girls during Puberty

• Activity Report

Activity 3-2: Changes in Boys during Puberty

• Activity Report

Activity 3-3: Knowing about Each Other

• Activity Report

Activity 3-4: Factors Influencing Puberty

• Activity Report

Teacher Materials

Activity 3-1: Changes in Girls during Puberty

• Activity Report Answer Key

Activity 3-2: Changes in Boys during Puberty

• Activity Report Answer Key

Activity 3-3: Knowing about Each Other

• Activity Report Answer Key

Activity 3-4: Factors Influencing Puberty

• Activity Report Answer Key

See Activities 3-1, 3-2, 3-3, and 3-4 in the student edition.

Activity 3-1: Changes in Girls during Puberty

• Make a transparency of the graph if you think it would be useful for your class. (Optional)

Activity 3-2: Changes in Boys during Puberty

• Make a transparency of the graph if you think it would be useful for your class. (Optional)

Activity 3-3: Knowing about Each Other

• None required

Activity 3-4: Factors Influencing Puberty

• Decide on group size.

Interdisciplinary Connections

Language Arts Students determine word origin. Discussion groups help students develop communication skills, and can lead to essay or journal writing.

Background Information

Higher levels of gonadal hormones that are produced by the testes (testosterone) and ovaries (estrogens) bring about the changes of puberty. The increased production of gonadal hormones are due to higher levels of gonadotrophins (FSH and LH) produced by the anterior pituitary, which is under the influences of gonadotropin releasing hormone (GnRH) released from the hypothalamus. What determines the timing of puberty is not entirely clear. It may be linked to the accumulation of a critical amount of fat in the body.

Boys, unlike girls, do not have a discrete event like menarche to mark sexual maturation. This is why studies such as the timing of puberty are more easily done with girls.

Girls now often receive information and advice, usually from their mothers, in anticipation of menarche. Boys often are told nothing about nocturnal emissions. Because of its sexual connotations, this important experience often is not addressed, causing puzzlement or distress to boys. Without launching into a full-scale discussion of sexuality, some of these issues can be discussed.

When a child enters puberty is purely a function of the levels of gonadal hormones in the body (discussed in the next section). The body's tissues will respond to the effect of hormones at any age. This explains cases of precocious puberty whereby a girl may develop breasts or a boy pubic hair at age 4. The most dramatic example is the youngest mother on record who gave birth to a normal child (through cesarean section) at the age of 5 years and 10 months.

These cases of precocious puberty are often due to some illness or abnormality, such as a brain tumor that triggers the chain of hormone production. But precocious puberty can also occur without apparent cause.

The same is true for delayed puberty. If a child, for whatever reason, fails to go through the normal stages of puberty on schedule, hormonal treatment can bring about these changes later, in adulthood. In other words, the ability of the body's tissues to respond to hormones is not lost with time.

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Date Created:

Feb 23, 2012

Sep 04, 2014
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