Adolescence is the period of transition from being a child to an adult which typically begins at the age of 11-12 and lasts upto 18-19. Adolescents are also called teenagers.
The process of physical, mental and emotional changes by which a child’s body becomes an adult is called puberty. This stage marks the onset of the ability to reproduce in boys and girls.
In males, the voice box protrudes from the throat and is also called the Adam’s apple.
Some of the mental changes that take place during puberty are:
• Children become over- sensitive or self-conscious
• Children become more independent than before
• Having difficulty in adjusting to changes in the body
• Conflicting thoughts as they gradually become capable of more mature thought processes
• Mood swings
• Sexual feelings
Adam’s apple is the voice box which becomes large in size and is seen as a protruding part of the throat among boys.
A sudden increase in height is typical during puberty. Elongation of bones of legs and arms causes increase in height.
Changes taking place in adolescents are:
• Boys and girls become capable of reproduction.
• Sudden increase in height due to elongation of bones of legs and arms.
• Significant change in voice, especially among boys
• Change in body shape such as broad shoulders in boys and narrow waist in girls
• Growth of facial hair in boys
• Formation of acne and pimples
The features that help us to visually distinguish males from females are called secondary sexual characteristics. Secondary sexual characteristics in males are growth of facial hair and in case of females, development of breasts.
Adolescent girls become capable of reproduction at the onset of menstruation. In girls, though the egg cells or ova are already present in their ovaries at birth, the maturation of the egg cells/ova starts with the onset of puberty. One ovum matures and is released by one of the ovaries, once every 28 to 30 days. During this period, the wall of the uterus also becomes thick, richly supplied with blood vessels, in order to receive the egg after fertilisation. In case the egg is fertilised, the resulting zygote attaches to the lining of the uterus, where it further develops, resulting in pregnancy. If, during this period, the sperm cell does not fuse with the female egg, the egg travels to the uterus which then sheds off its inner of soft tissues and blood vessels. This causes bleeding in women which is called menstruation.
The appearance of acne and pimples during puberty is due to the increased activity of sweat and sebaceous glands, which is also a common secondary sexual characteristic. The hair follicles on our skin are connected, below the surface, to sebaceous glands. These glands secrete an oily substance called sebum that lubricates the skin and hair. The sebaceous glands along with the sweat glands become more active during puberty. Unfortunately, this oily substance sometimes clogs the surface of the skin, gluing dead skin cells to the skin surface. This prevents more oil from flowing to the surface, encouraging the growth of bacteria and producing the inflammation and redness characteristics of pimples.
Some teenagers have disproportionate sized body parts during adolescence because all body parts do not grow at the same pace. Adolescents need not to worry about these disproportionate body parts since during the course of time, the body will become balanced.
Adolescence begins around the age of 11 and lasts up to 18 or 19 years. Since this period includes the teens which lie in the age group of 13 to 18 years, adolescence is also called teenage.
Iron is necessary for the body for the formation of red blood cells. Jiggery, meat, gooseberry and green leafy vegetables are some iron-rich foods that help the body create more blood cells.
Mammary glands are present from birth but become capable of secreting milk only when the female becomes sexually mature. These glands secrete milk after the woman becomes a mother.
The change from larva to adult stage is called the metamorphosis stage and in case of frogs, thyroxine is the hormone that is responsible for this.
(a) Diabetes Decreased or no secretion of insulin from pancreas or the inability of cells in responding to the insulin levels. This leads to high blood sugar levels in the body causing ill effects on health.
(b) Goitre Decreased or no secretion of thyroxine from thyroid gland. Insufficiency of thyroxine causes the thyroid glands to enlarge and reduces the rate of metabolism in cells.
(a) Sources of Iron leafy vegetables, jaggery
(b) Proteins Pulses, meat
(c) Carbohydrates Cereals, milk
A healthy or nutritious diet for adolescents provides enough calories and nutrients for growth and good health. That is why it is necessary to eat the right kind of food.
A girl should not become pregnant during teenage years because early motherhood can cause health problems in both the mother and the child. Problems such as high blood pressure or delivery of an immature or poorly developed baby are a few of the possible complications.
The following health measures should be taken to maintain good reproductive health:
• A balanced diet
• Adequate physical exercise
• Good personal hygiene
There are 23 pairs of chromosomes in the cells of humans. Of these 2 chromosomes, X and Y, determine the sex of the resultant zygote.
The sex of an unborn baby is determined by the type of sperm that fuses with the egg cell, whether Y-containing sperm or X-containing sperm.
The individual with XY chromosomes will be a male.
(a) Hormone The chemicals secreted by the endocrine or ductless glands directly into blood stream are called hormones. They act as messengers that control and coordinate various parts and actions of the body.
(b) Endocrine glands- Ductless glands that secrete chemicals called hormones directly into the bloodstream are called endocrine glands.
(c) Testosterone: This is the male sex hormone released by the testes at the onset of puberty. It is responsible for the production of sperms and male secondary sexual characteristics e.g. growth of facial hair, cracking of voice, chest development etc.
(d) Estrogen: This is the female sex hormone produced by ovaries, which is responsible for maturation of ovum and secondary sexual characteristics in females e.g. onset of menstrual cycle, development of the mammary glands etc.
(e) Ductless Glands: Ductless glands are basically the organs which do not have ducts like vessels or tubes to transport fluid throughout the body. They secrete the hormones directly into the blood stream, which in turn carries them to different parts of the body.
The role of hormones in initiating reproductive function is as follows:
• Hormones from pituitary glands stimulate the testes and ovaries to release sex hormones, testosterone and estrogen respectively.
• These sex hormones reach the target sites via blood.
• These sex hormones then produce physical, mental and emotional changes in the body signalling puberty.
In females, the reproductive phase of life begins at puberty, with the onset of menstruation and continues till they reach the age of 45-50 years, i.e. menopause. The eggs/ovum, already present in the ovaries of the girls begins to mature with the onset of puberty. One mature ovum is released by one of the ovaries every month. During this period, the walls of the uterus become thick due to increased blood supply, so as to receive the fertilized egg. In case fertilization occurs, the zygote attaches to the lining of the uterus, where it develops further, resulting in pregnancy. In case fertilization does not occur, the uterine lining is shed off along with the blood vessels resulting in menstrual flow or bleeding.
The hormones secreted from testes and ovaries are called sex hormones. The male hormone or testosterone is released by the testes, and the female hormone or estrogen is released by the ovaries, with the onset of puberty.
Function of Testosterone-male sex hormone:
The male hormone is responsible for the production of sperms and secondary sexual characteristics in boys e.g. growth of facial hair, i.e. moustache and beard, hair on chest and armpits, cracking of voice etc.
Function of Estrogen-female sex hormone:
The female hormone or estrogen is responsible for the maturation of egg, onset of menstruation and secondary sexual characteristics in girls, such as development of breasts and milk secreting glands or mammary glands inside the breasts, widening of hips, hair growth in armpits and pubic region etc.
(a) Secondary Sexual Characters: Though the testes and ovaries are the main reproductive organs i.e., the primary sex-organs that produce the gametes, i.e. sperms and ova, other bodily changes appear in adolescent boys and girls that help to distinguish between them. These changes that appear at puberty, which help to differentiate between boys and girls are called secondary sexual characteristics. In girls, the breasts begin to develop at puberty and boys begin to grow hair on the face and chest. Some changes appear in both of them, such as hair growth in the armpits and the pubic region.
(b) Sex determination in an unborn baby: All human beings have 23 pairs of chromosomes named X and Y. A female has two X chromosomes, while male has one X and one Y chromosome. When a sperm containing X chromosome fertilizes the egg, the zygote would have two X chromosomes and develops into a female child whereas when the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child. So, the sex of a baby is determined by the chromosomes of the male.