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Cell biology, a core discipline within Biology Topics, investigates the structure and function of cells.
What is the age limit for Puberty? What are the Changes involved in Puberty?
We will now discuss puberty in detail.
Although a baby is born with a full set of reproductive organs (male or female organs), these organs do not function during the first 10 or 12 years of life. Under the influence of hormones produced in the body, the reproductive organs become active at the time known as puberty. In other words, the reproductive systems of humans (boys and girls) start functioning at the time called puberty.
At puberty, sex hormones (or gametes) begin to be produced due to which the boys and girls become sexually mature. The period during which adolescent boys and girls reach sexual maturity and become capable of reproduction is called puberty. In other words, after attaining puberty, an adolescent (boy or girl) becomes capable of having a baby. Puberty is a period of several years in which rapid physical growth (or rapid body growth) occurs leading to sexual maturity.
In fact, puberty is the time when a child’s body starts changing into an adult’s body. Puberty tends to start earlier in girls (females) than in boys (males). Generally, girls attain puberty at a lower age of 10 to 13 years while boys reach puberty at a comparatively higher age of 12 to 14 years. At puberty, many changes occur in the bodies of boys and girls. In both, boys as well as girls, there is a rapid increase in the rate of growth (height, etc.) during puberty.
Puberty is marked by the development of secondary sexual characteristics in boys and girls (such as growth of facial hair and deeper voice in boys; and development of breasts and start of menstruation in girls). The most significant sign of puberty in girls is the beginning of menstruation (or monthly periods).
The various changes which occur in boys during puberty are as follows :
- Hair grow on the face of boys (in the form of moustache and beard), and on chest.
- Voice deepens in boys. It becomes low pitched voice.
- Testes start to make sperms.
- Testes and penis become larger.
- Chest and shoulders of boys broaden (become wider).
- Body becomes muscular (due to development of muscles).
- Hair grow in armpits and in pubic regions (genital area) between the thighs.
- Rapid increase in height occurs.
- Feelings and sexual drives associated with adulthood begin to develop.
The various changes which occur in girls during puberty are as follows :
- Breasts develop and enlarge in girls.
- Ovaries start to release eggs (or ova).
- Menstruation (monthly periods) begin.
- Ovaries, oviducts, uterus and vagina enlarge.
- Hips of girls broaden (become wider). Extra fat is deposited on hips and thighs.
- Hair grow in armpits and in pubic regions (genital area) between the thighs (This change is the same as in boys).
- Rapid increase in height occurs (This change is the same as in boys).
- Feelings and sexual drives associated with adulthood begin to develop (This change is also the same as in boys).
All the changes which occur in boys and girls at puberty are brought about by various hormones. When a boy or girl reaches puberty, he (or she) becomes an adolescent. Adolescence continues until the age of about 18 (or 19) years when the growth stops and the person becomes an adult. We will now describe the changes taking place during puberty in detail.
Changes At Puberty
Puberty marks the beginning of the reproductive period when one becomes capable of reproduction. We will now discuss some of the changes which take place in adolescent boys and girls at puberty, in detail.
1. Increase in Height
The most conspicuous change (clearly visible change) during puberty is the sudden increase in the height of boys and girls. At the time of puberty, the long bones (the bones of arms and legs) elongate or lengthen and make a person tall. Thus, children gain a lot of height during puberty. Initially, girls grow faster than boys but by about 18 years of age, both boys and girls reach their maximum height. Generally, the maximum height of girls is slightly less than that of boys.
The rate of growth in height varies in different persons. Some boys and girls may grow suddenly at puberty and then slow down, while others may grow gradually. All the parts of the body do not grow at the same rate. Sometimes the arms and legs, or hands and feet of adolescent boys and girls look oversized and out of proportion with the body. But soon the other parts catch up with them in growth. This results in a more proportionate body. The average rate of growth in height of boys and girls with age is given in the following table.
Age | Percentage of full height in boys | Percentage of full height in girls |
8 years | 72% | 77% |
9 years | 75% | 81% |
10 years | 78% | 84% |
11 years | 81% | 88% |
12 years | 84% | 91% |
13 years | 88% | 95% |
14 years | 92% | 98% |
15 years | 95% | 99% |
16 years | 98% | 99.5% |
17 years | 99% | 100% |
18 years | 100% | 100% |
The figures given in second and third column of the above table tell us the percentage of full height which a person (boy or girl) has reached at the age given in the first column. For example, at the age of 10 years, a boy reaches only 78 percent of his full height whereas a girl reaches 84 percent of her full height. Please note that the figures on the rate of growth in height given in the above table are only indicative. There may be variations from person to person.
By using the data given in the above table, we can draw a graph to show the variation in the ‘percentage of full height’ in boys and girls with age’. We take ‘age’ on x-axis and ‘percentage of full height’ on y-axis, and plot the various readings given in the above table on the graph paper. The graph thus obtained is shown in Figure. We can see from the graph shown in Figure 1 that initially the height of girls increases at a faster rate
than that of boys but by about 18 years of age, both boys and girls reach their maximum height. By using the graph shown in Figure, we can find out the percentage of full height of a boy or girl at any age, say 12.5 years. We can also calculate the full height which a boy or girl might eventually reach. This will become more clear from the following discussion.
If we know the present height of a person (boy or girl) and the percentage of his (or her) full height at present age, we can calculate the full height of the person which he (or she) will eventually reach. This can be done by using the formula :
Full height of a person \(=\frac{\text { Present height of person }}{\text { Percentage of full height at present age }}\) × 100
We can use the unit of centimetre or metre for height. The calculation of full height of a person (boy or girl) will become clear from the following example.
Example Problem.
A ten year old boy is 125 cm tall. If the present height of the boy is 78% of his full height, calculate the full height which the boy will eventually reach at the end of growth period.
Solution:
Here, Present height of boy = 125 cm
Percentage of full height =78
So, Full height of boy \(=\frac{\text { Present height of boy }}{\text { Percentage of full height }}\) × 100
= \(\frac{125}{78}\) × 100
= 160.25 cm
Thus, the full height of boy will be 160.25 centimetres.
Please note that the height of a person depends on the genes inherited from the parents. For example, if both the parents (or one of the parents) are very tall, the son or daughter is likely to be very tall. The height of a person is more or less similar to that of some family member.
2. Change in Body Shape and Appearance
When a child is small, sometimes it becomes difficult to tell from appearance whether it is a boy or a girl. This is because small boys and girls have the same body shape (see Figure 2). So, it is usually the type of clothes worn by a small child which help us in telling whether it is a boy or a girl (and not its body shape). When puberty sets in, a time of rapid changes in body shape and appearance starts in boys and
girls which make the boys and girls look different from one another (see Figure). Actually, testes in boys and ovaries in girls make different hormones which make the bodies of boys and girls to develop in different ways. So, the changes in body shape occurring in adolescent boys and girls at puberty are different. Some of the changes in body shape and appearance in boys and girls brought about by the onset of puberty are as follows :
- Boys develop broader shoulders and wider chests than girls (see Figure).
- Girls develop broader hips than boys. Due to this, the region below the waist becomes wider in girls (see Figure).
- Boys develop more muscle than girls. So, the body of boys looks more muscular than that of girls.
- Girls develop breasts. This also changes the body shape of grown up girls and makes them look different from boys.
- Boys develop Adam’s Apple (a bulge in front of throat) which makes them look different from girls.
- Boys develop facial hair (moustache and beard) but the girls do not have facial hair. So, growth of facial hair makes boys look different from girls.
3. Change in Voice
When we are talking, our voice (or sound) is produced by the voice box. The voice box is in our throat. Voice box is also called larynx. At puberty, the voice box (or larynx) begins to grow in boys as well as in girls. The growth of voice box in boys is much more than the growth of voice box in girls. Due to this, the voice box in boys becomes much bigger than the voice box in girls. This means that the grown up boys have a bigger voice box in their throat whereas grown up girls have a smaller voice box in their throats.
The bigger voice box in boys gives deeper voice (or low pitched voice) to the boys. Thus, the voice of boys changes at puberty and becomes deeper because their voice boxes enlarge too much and become bigger in size. The bigger (or larger) voice box in a grown up boy can be seen as a bulge (or projection) in front of the throat (or neck). The bulge (or projection) at the front of throat or neck in grown up boys is called
Adam’s Apple (see Figure). Adam’s Apple is formed in grown up boys because of their bigger voice box in the throat. It is called an Adam’s Apple after the story of Adam (the first man created by God) and Eve (the first woman created by God) described in Bible in which Adam ate a piece of forbidden fruit (apple) in the Garden of Eden which got stuck in his throat. An Adam’s Apple sometimes looks like a small rounded apple just under the skin in front of the throat. Thus, Adam’s Apple is a feature of throat (or neck) of grown up boys. It is a bulge (or bump) in the throat or neck.
A rough and harsh voice is called ‘hoarse’ voice. Hoarse voice is called ‘phati awaaz’ in Hindi. In adolescent boys, sometimes the muscles of the growing voice box go out of control due to which Figure. Adam’s Apple in a grown up boy. their voice becomes hoarse. This state of hoarseness of voice may remain for a few days or few weeks after which the voice becomes normal. During this time, the vocal cords of the voice box (or larynx) get adjusted to the new, bigger size of the voice box.
In girls, the voice box (or larynx) is comparatively small in size due to which it is hardly visible from outside. So, girls do not develop Adam’s Apple at puberty. The smaller voice box in girls gives shrill voice (high pitched voice) to the girls.
Before we go further, we should know the meaning of the terms such as pimples, acne, sebaceous glands and sweat glands. Pimples are small red spots on the face of a person. Acne is a skin condition marked by the eruption of numerous red pimples on the face. Sebaceous glands are the small glands in the skin which secrete an ‘oil’ (called sebum) through skin pores to lubricate and protect the surface of skin. ‘Sebaceous glands’ are commonly known as ‘oil glands’. Sweat glands are the tiny glands in the skin which secrete ‘sweat’ (pasina).
4. Development of Pimples and Acne on the Face
Many young boys and girls get pimples and acne on the face during puberty. The pimples and acne are formed due to the increased activity of sebaceous glands and sweat glands present in the skin. This happens as follows: The level of hormones in boys and girls rises too much at puberty. These hormones stimulate the sebacious glands and sweat glands present in the skin. The increased activity of sebaceous glands (oil glands) causes them to secrete more ‘oil’ and the increased activity of sweat glands makes them secrete more sweat. The excess oil and sweat get collected in the tiny pores of the skin.
The accumulation of oil, sweat and dead skin cells blocks the tiny pores in the skin of the face. Bacteria grow in the mixture of oil, sweat and dead skin cells in the ‘blocked skin pores’ causing the swelling and redness of skin which leads to the formation of pimples (see Figure). Thus, pimples are caused by the clogged and infected skin pores. When outbreaks of too many pimples occur often, it is considered acne. Pimples and acne occur most commonly during adolescence. In most boys and girls, pimples and acne diminish over time and tend to disappear by the time one reaches the age of 18 or 19 years. In some, they continue into adulthood
5. Development of Sex Organs
The onset of puberty brings about complete growth and development of sex organs in boys and girls due to which their reproductive systems start functioning at this stage. For example:
(i) At puberty the male sex organs like testes and penis enlarge and develop completely The testes begin to produce male sex cells called ‘sperms’ at puberty. This makes the male (boy’s) reproductive system functional at puberty
(ii) At puberty, the female sex organs like ovaries, oviducts and uterus enlarge and develop completely. The eggs (or ova) begin to mature at this stage. The ovaries start releasing mature eggs (or ova) at puberty. This makes the female (girl’s) reproductive system functional at puberty.
6. Reaching Mental, Intellectual and Emotional Maturity
When a person reaches puberty, he (or she) becomes an adolescent. Adolescence continues up to the age of 18 or 19 years. During adolescence, a boy (or girl) reaches mental, intellectual and emotional maturity (Mental is called rnaansik, intellectual is called baudhik and emotional is called bhavatamak in Hindi).
(i) Adolescence is a period which brings maturity in a person’s way of thinking. At this stage, adolescent boys and girls spend considerable time thinking about many things occurring in their minds. During adolescence, mental maturity makes the boys and girls more independent than before.
(ii) Adolescence is a period which also brings intellectual maturity Due to intellectual development, the boys and girls get into the habit of reasoning, and understanding things objectively. In fact, adolescence is the time in one’s life when the brain has the greatest capacity for learning.
(iii) The changes which occur in the body of boys and girls during adolescence may cause emotional swings. These emotional swings show intense feelings such as joy, anger, boredom, worries or sadness which are not based on reasoning or knowledge. The adolescents also become self-conscious (unduly aware of one’s actions leading to nervousness). Sometimes, the adolescents feel insecure (not confident) while trying to adjust to the changes in body and mind. There is, however, no reason to feel insecure. The changes which take place in body and mind during adolescence are a natural part of the growing up process. Every human being has to pass through this stage. Our parents have passed through this stage, now we are passing through this stage, and one day our children will also pass through this stage in life.