adolescence

CLASS 8 SCIENCE Chapter- ENDOCRINE SYSTEM AND ADOLESCENCE | NOTES

INTRO – ENDOCRINE SYSTEM AND ADOLESCENCE Adolescence is one of the most exciting phases of life. It usually begins around 10–12 years and continues till 18–19 years. During these years, you may notice many things happening at the same time. The endocrine system is a network of glands that produce hormones — special chemicals that act like tiny messengers. These hormones travel in your blood and tell different parts of your body when to grow, how to develop, and how to feel. Endocrine system = Glands + Hormones The Endocrine System is the body’s internal communication network, and adolescence is the time when this network becomes super active. HORMONES AND ENDOCRINE GLAND *What Are Glands Glands are special organs in our body that make and release various chemical substances.These chemicals help the body grow, stay healthy, digest food, control temperature, and even fight stress. There are two main types of glands: 1. Exocrine Glands – The Ones with Ducts 2. Endocrine Glands – The Ductless Ones *what are Hormones Hormones are chemical messengers made by endocrine glands. They travel through blood and control almost every activity in the body. *Major Endocrine Glands and Their Hormones 1) Pituitary Gland – “The Master Gland” 2) Thyroid Gland – Body’s Energy Manager 3) Adrenal Glands – “Emergency Responders” 4) Pancreas – Blood Sugar Controller 5) Reproductive Glands – Puberty Controllers     –Testes (in boys)      –Ovaries (in girls) PUBERTY Puberty marks the biological start of adolescence. It is the phase when the body becomes capable of reproduction and starts developing new characteristics. Girls usually begin puberty between 10–14 years Boys usually begin puberty between 11–15 years Hormones play the main role in triggering all changes of puberty. *The various changes which occur in boys during puberty: *The various changes which occur in girls during puberty: *Changes in Reproductive Organs As puberty begins, the reproductive organs finally mature and become fully functional. This happens due to hormonal changes controlled by the pituitary gland. – In Boys –In Girls *Menstrual Cycle (28-Day Cycle) If the egg is not fertilized, both the egg and the thick uterine lining are shed from the body. This flow of blood and tissue is called menstruation. The human menstrual cycle has four phases: Phase 1: Menstruation (Day 1–4) Phase 2: Follicular Phase (Day 5–12) Phase 3: Ovulation (Day 13–14) Phase 4: Luteal Phase (Day 15–28) #Menarche: First menstrual flow (usually at the start of adolescence). #Menopause: Menstrual cycle stops permanently (around age 45–50). *Determination of the Sex of the Baby Humans have 23 pairs (46 total) chromosomes. Out of these, 22 pairs are normal body chromosomes. The 23rd pair is called the sex chromosomes because they decide whether the baby will be a boy or girl. Girls have XX chromosomes, while boys have XY chromosomes. In humans, the mother’s egg always carries only one type of sex chromosome – X. However, the father’s sperms are of two types: some carry X, and some carry Y. This difference plays the main role in deciding the baby’s sex. X (egg) + X (sperm) = XX → Girl baby X (egg) + Y (sperm) = XY → Boy baby Therefore, the sex of the baby depends completely on which sperm reaches the egg first — the X-sperm or the Y-sperm. This means the father determines the sex of the baby, not the mother. *Emotional Changes at Puberty During adolescence, hormones affect not only the body but also the mind. Common emotional changes: NUTRITIONAL REQUIREMENTS DURING ADOLESCENCE Good food is not just fuel—it’s the building block of a strong and confident future. During adolescence, the body needs: *Essential Nutrients Needed by Adolescents PERSONAL HYGIENE DURING ADOLESCENCE During Adolescence, the body becomes more prone to sweat, oiliness, skin problems, and infections. That’s why maintaining personal hygiene is extremely important. Cleanliness during adolescence keeps the body healthy, boosts confidence, and prevents diseases. *Essential Personal Hygiene Habits During Adolescence PHYSICAL FITNESS DURING ADOLESCENCE Physical fitness means the ability of the body to perform daily activities without getting tired easily and with strength, stamina, and flexibility. It keeps both the body and mind strong during the rapid growth of adolescence. A physically fit adolescent can handle daily tasks effortlessly, think clearly, and stay confident. *How Adolescents Can Stay Physically Fit DRUG ABUSE AND AIDS *Drug Abuse Drug abuse means misusing harmful substances such as tobacco, alcohol, or other addictive drugs. These substances affect the brain, damage the body, and can create lifelong health problems. The harmful Effects of Drug Abuse are as follow: *AIDS AIDS stands for Acquired Immuno Deficiency Syndrome. It is caused by a virus called HIV (Human Immunodeficiency Virus). HIV attacks the body’s immune system, making it difficult to fight infections. A person with AIDS becomes weak and easily gets sick because the body’s defence system is damaged. HIV spreads through specific ways – Unprotected sexual contact, Sharing infected needles or syringes, Transfusion of infected blood. It is NOT spread through – Touching, hugging, or shaking hands, Sharing food or water, Mosquito bites, Sitting in the same classroom.

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