Chapter 10: Reaching the Age of Adolescence PDF

# Chapter 10: Reaching the Age of Adolescence ## Adolescence and Puberty ### Adolescence: - The period between childhood and adulthood is called adolescence. - During this period, the body undergoes changes leading to reproductive maturity. - Adolescence begins around the age of 10 or 11 years and...

# Chapter 10: Reaching the Age of Adolescence ## Adolescence and Puberty ### Adolescence: - The period between childhood and adulthood is called adolescence. - During this period, the body undergoes changes leading to reproductive maturity. - Adolescence begins around the age of 10 or 11 years and lasts up to 18 or 19 years of age. - This period covers the teen's age of 13 to 18 years. Adolescents are also called teenagers. - *Note:* Adolescence in girls may begin a year or two earlier than in boys. It may vary from person to person. ### Puberty: - The period during adolescent boys and girls reach sexual maturity and become capable of reproduction is called puberty. - Girls attain puberty at the age of 10 to 13 years and boys at the age of 12 to 14 years. ## Changes at Puberty 1. **Increase in height:** - The most conspicuous change during puberty is the sudden increase in the height of boys and girls. - During puberty, the long bones (bones of legs and arms) elongate and make a person tall. - During puberty, the girls grow faster than boys but by the age of 18 years, both girls and boys reach their maximum height. 2. **Change in body shape and appearance:** - **Changes in boys:** - Boys develop broader shoulders, wider chest, and Adam's apple (protruding part of the throat). - Boys also develop facial hair, mustache, and beard. - **Changes in girls:** - Girls develop broader hips, the region below the waist becomes wider in girls. - Girls also develop breasts. 3. **Change in voice:** - During puberty, boys develop a larger voice box (larynx). This can be seen in boys as a protruding part of the throat called Adam's apple. - The larynx is small in girls so it is not clearly visible. - *Note:* Boys have deep voices and girls have a very high-pitched voice. 4. **Development of pimples and acne on the face:** - The secretion of sweat glands and oil glands (sebaceous glands) increases during puberty. - Due to this, pimples and acne are formed on the face during this time. 5. **Development of sex organs:** - During puberty, the male sex organs like the testis and penis develop completely. - During this time, the penis starts producing sperms. - In girls, the ovaries enlarge and start releasing mature eggs. 6. **Reaching mental, emotional, and intellectual maturity:** - During adolescence, boys and girls become more mature, independent. - Adolescence is the time in boys' and girls' life when the brain has the greatest capacity for learning. ### The average growth rate in height of boys/girls with age: $Full \ height \ of \ a \ person = \frac{Present \ height \ of \ person}{Percentage \ of \ full \ height \ at \ present \ age} \times 100$ ## Secondary Sexual Characters - The sexual characteristics which are present at birth are called **primary sexual characters**. - It includes internal and external sex organs which are present in babies (girls and boys) at the time of their birth. - During puberty, the reproductive organs start producing sperms and ova in boys and girls. - Breast development occurs in girls and facial hair, moustaches and beards begin to grow in boys. - All these features help to distinguish the male from female is called **secondary sexual characters**. ### Secondary characters in males are: - Hair growth on the face, chest and underarms. - Shoulder and chest broaden. - Adam's apple develops in the front throat in boys. ### Secondary characters in females are: - Development of breast. - Hips broaden and become curved. - Hair grows under the arms. ## Role of Hormones in Initiating Reproductive Function ### Hormones: - All the changes which occur during puberty in boys and girls are controlled by hormones. - Hormones are chemical substances that are made and secreted by specialized tissues in the body called **endocrine glands**. - The endocrine gland secretes hormones directly into the blood and it is carried by the bloodstream to a particular body part called the **target site**. ### Sex Hormones: - Sex hormones are involved in the development and control of the reproductive organs and secondary sexual characteristics. - The production of sex hormone is under the control of another hormone secreted by the pituitary gland. - There are two types of sex hormones: - **Testosterone** (male hormone) - **Estrogen** (female hormone). #### (a) Testosterone: - Testes make a male sex hormone called testosterone at the time of puberty. - This causes changes in boys during puberty. #### (b) Estrogen: - During puberty in girls, the ovaries begin to produce the female sex hormone called estrogen. - Estrogen hormone produces female secondary sexual characteristics (development of breast, broaden hips, growth of hair under the arms, etc.). *Tip:* Milk secreting gland or mammary glands develop inside the breasts of the female is under the control of the pituitary gland. ## Reproductive phase of life in humans - The capacity to produce female gamete (ovum) in a woman starts at puberty (10-12 years) and lasts till the age of 45 to 50 years of age. - But in males, the capacity of producing male gametes (sperms) usually lasts throughout life. Due to this, the reproductive phase of life in men is much longer than in women. ## Menstruation: - With the onset of puberty, the egg begin to mature in the ovaries of a woman. - One mature ovum is released by one of the ovaries of the women once in about 28-30 days. - During this period the inner lining of the uterus grows and becomes thick to receive the fertilized egg. - In case the fertilization of eggs by a sperm occurs, the fertilized egg divides to form an embryo. - This embryo then gets embedded in the thick uterus. This results in pregnancy. - If the fertilization does not occur, the egg released by the ovary dies within a few days and the thick lining of the uterus along with blood vessels breaks down. - This causes bleeding in women every month which is called menstruation - **Menarche:** The first occurrence of menstruation at puberty is called menarche. - **Menopause:** At the age of 45-50 years the menstruation stops completely in women and it is termed menopause. ## How is the Sex of the Baby Determined? - All human beings have 23 pairs (46) of chromosomes in the nuclei of their normal body cell. - Out of these 1 pair (2) of chromosomes are called sex chromosomes. - There are two types of sex chromosomes: X and Y chromosome. - The gametes (sperm and ova) contain only 23 single chromosomes. Hence, they have only one sex chromosome (either X or Y). - In females, all the gametes (eggs) contain X chromosomes. - On the other hand, in males, half of the gametes (sperms) have X chromosomes and half of the gametes have Y chromosomes. - The baby developed from XX combination of sex chromosomes is a girl and the baby developed from XY combination of sex chromosomes is a boy. - Thus, the sex chromosomes of the father determine the sex of the baby. ## Hormones other than Sex Hormones - A gland is a structure that secretes a specific substance in the body. - There are two types of glands in our body: #### (a) Exocrine gland: - The gland which secretes its product into a duct (tube) is called the exocrine gland. Eg: Salivary gland, sweat gland, and oil gland. #### (b) Endocrine gland: - The gland which secretes its product directly into the bloodstream is called the endocrine gland. They do not have ducts so they are also called ductless glands. - Some example of the endocrine gland is the pituitary gland, thyroid gland, pancreas, and adrenal gland. ## Thyroid gland: - The thyroid is a large endocrine gland in the neck. - The thyroid gland produces a hormone called thyroxin. - Thyroxin hormone controls the rate of body metabolism. - The thyroid gland requires iodine in order to produce the thyroxin hormone. - The deficiency of iodine in the diet causes a disease known as goiter. ## Adrenal gland: - An adrenal gland is an endocrine gland. - It produces a hormone called adrenaline. - Adrenaline helps our body to adjust the stress, anger, fear, shock, surprise, anger, or excitement. ## Pancreas: - The pancreas is an endocrine gland that secretes the hormones called insulin. - The function of insulin is to lower the blood sugar level. - The deficiency of insulin hormone causes a disease called diabetes. - The person suffering from diabetes is characterized by a large quantity of sugar in the blood and the person is advised to take insulin injection to control sugar level in the blood.