INCREASE IN HEIGHT

INCREASE IN HEIGHT

The most conspicuous change during puberty is the sudden increase in height. At this time the long bones, that is, the bones of the arms and the legs elongate and make a person tall.

Activity 10.1:

*   The following chart gives the average rate of growth in height of boys and girls with age. The figures in columns 2 and 3, give the percentage of the height a person has reached at the age given in column 1.

*   For example, by the age 11, a boy has reached 81% of his probable full height, while a girl has reached 88% of her full height. These figures are only representative and there may be individual variations.

*   Use the Table for your friends and work out how tall they are likely to be. Find out who is likely to be the tallest and who might be the shortest in your class.

Calculation for full height (cm) =\(\frac{present \,height(cm)}{\%\,of\, height \,at\,this\,age(given\, in\, chart)}\times100\)

Example:

A boy is 9 years old and 120 cm tall. At the end of the growth period, he is likely to be

\((\frac{120}{75}\times100)cm=160\,cm\,tall\)

Activity 10.2:

*   Use the data given in Activity 10.1 to draw a graph.

*   Take age on the X-axis and percent growth in height on the Y-axis.

*   Highlight the point representing your age on the graph.

*   Find out the percentage of height you have already reached.

*   Calculate the height you might eventually reach.

*   Tally your graph with the one given here (Fig. 10.1).

Figure 10.1: Graph showing percentage of height with age

Initially, girls grow faster than boys but by about 18 years of age, both reach their maximum height. The rate of growth in height varies in different individuals. Some may grow suddenly at puberty and then slow down, while others may grow gradually.

All parts of the body do not grow at the same rate. Sometimes the arms and legs or hands and feet of adolescents look oversized and out of proportion with the body. But soon the other parts catch up and result in a proportionate body.

You must have noticed that the height of an individual is more or less similar to that of some family member. This is because height depends on the genes inherited from parents. It is, however, very important to eat the right kind of food during these growing years. This helps the bones, muscles and other parts of the body get adequate nourishment for growth. You will find the nutritional needs of adolescents discussed later in the lesson.

Source: This topic is taken from NCERT TEXTBOOK

CHANGE IN BODY SHAPE AND VOICE

CHANGE IN BODY SHAPE AND VOICE

Change in body shape

Have you noticed that boys in your class have broader shoulders and wider chests than boys in junior classes? This is because they have entered the age of puberty when shoulders generally broaden as a result of growth. In girls, the region below the waist becomes wider.

In boys, the muscles of the body grow more prominently than in the girls. Thus, changes occurring in adolescent boys and girls are different.

Voice change

Did you notice that sometimes the voice of some of the boys in your class cracks? At puberty, the voice box or the larynx begins to grow. Boys develop larger voice boxes. The growing voice box in boys can be seen as a protruding part of the throat called Adam’s apple (Fig. 10.2). In girls, the larynx is hardly visible from the outside because of its small size. Generally, girls have a high pitched voice, whereas boys have a deep voice. In adolescent boys, sometimes, the muscles of the growing voice box go out of control and the voice becomes hoarse. This state may remain for a few days or weeks after which the voice becomes normal.

Figure 10.2: Adam’s apple in a grown up boy

Source: This topic is taken from NCERT TEXTBOOK

INCREASED ACTIVITY OF SWEAT AND SEBACEOUS GLANDS

INCREASED ACTIVITY OF SWEAT AND SEBACEOUS GLANDS

During puberty the secretion of sweat glands and sebaceous glands (oil glands) increases. Many young people get acne and pimples on the face at this time because of the increased activity of these glands in the skin.

A few glands such as sweat glands, oil glands and salivary glands release their secretions through ducts. Endocrine glands release hormones directly into the bloodstream. So, they are also termed ductless glands.

Source: This topic is taken from NCERT TEXTBOOK

DEVELOPMENT OF SEX ORGANS

DEVELOPMENT OF SEX ORGANS

Look up Fig. 9.1 and 9.3 which show sex organs of humans. At puberty, male sex organs like the testes and penis develop completely. The testes also begin to produce sperms. In girls, the ovaries enlarge and eggs begin to mature. Also ovaries start releasing mature eggs.

Figure 9.1: Male reproductive organs in humans

Figure 9.3: Female reproductive organs in humans

Source: This topic is taken from NCERT TEXTBOOK

REACHING MENTAL, INTELLECTUAL AND EMOTIONAL MATURITY

REACHING MENTAL, INTELLECTUAL AND EMOTIONAL MATURITY

Adolescence is also a period of change in a person’s way of thinking. Adolescents are more independent than before and are also self-conscious. Intellectual development takes place and they tend to spend considerable time thinking. In fact, it is often the time in one’s life when the brain has the greatest capacity for learning. Sometimes, however, an adolescent may feel insecure while trying to adjust to the changes in the body and mind. But as adolescent learners, you should know that there is no reason to feel insecure. These changes are a natural part of growing up.

Source: This topic is taken from NCERT TEXTBOOK