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Development of secondary sexual characters is influenced by the hormones secreted in the body during puberty and in the adolescence stage. Hormones are defined as the chemical substances secreted from the endocrine glands present in our body.
Male hormone:Testosterone is a male hormone released by the testes during puberty.
Female hormone:Estrogen is a female hormone responsible for development of breasts and activation of mammary glands to lactate after pregnancy.
Both male and female hormones are regulated by a gland called pituitary gland present in the brain. Hormones secreted by the pituitary gland activate the secretion of testosterone in male testes and estrogen in females. These hormones are released into blood stream and are transported to the target site, thus stimulating changes during puberty. Thus hormones play a main role in initiating the reproductive phase in humans.
Menstrual cycle in females:
The reproductive phase in females starts from the onset of puberty (12 years of age) and lasts up to 45-50 years of age. After the onset of puberty, the ovaries start to produce mature eggs and release them once in 28 to 30 days. This phenomenon of releasing mature eggs once in every month is known as menstrual cycle. The first menstrual cycle on the onset of puberty is called as menarche. Menstrual cycle should occur once in every month, failure of which results in problems in fertility. Initially the menstrual cycle is irregular due to increased production of hormones, but it soon becomes regular. In a normal menstrual cycle period, the wall of uterus holding the egg becomes thick. If the egg is fertilized with sperm during this period, the ovary does not fall and results in development of an embryo. This results in pregnancy. At the age of 45-50, the menstrual flow is arrested resulting in end of reproductive phase. This is known as menopause. As a woman reaches menopause period, there are lot of hormonal changes in her body resulting in fluctuations of emotions, intellectual thinking and health.
Determination of sex:
Thread-like structures called chromosomes are present in nucleus of each and every cell. All humans have 21 pairs of chromosomes in each cell. Additionally, there are 2 pairs of specialized chromosomes namely, X chromosome and Y chromosome. These chromosomes are otherwise called as sex chromosomes. A female has 2 X chromosomes, whereas a male has one X and one Y chromosome. The male and female gametes have only one set of these chromosomes and hence are haploid in nature. That is, a mature egg has one X chromosome and a sperm has one X and one Y chromosome. Once the egg is fertilized with a sperm, a zygote is developed. If the zygote has 2 X chromosomes (one from male gamete and another from female gamete) then the embryo will develop into female and if the zygote has one X and one Y chromosome, then the embryo will develop into a male. Hence, this indicates that Y chromosome from the father is responsible for the determination of sex of the child.
Adolescence and health:
As adolescence period is all about growing up, it is essential to maintain a strict balanced diet which is rich in nutrition. Nutrients not only enhance growth and development of the body but also play a role in regulating the fluctuating hormones of our body during puberty. A high quantity of water intake is a must to regulate the hormones secreted from other glands of our body.