Reaching at the Age of Adolescence Chapter Summary Class 8
ADOLESCENCE – Adolescence is the transitional period between childhood and adulthood. It begins around the age of 10-11 and lasts until the age of 19. The period of adolescence is known as teenage. Besides the physical changes of puberty, adolescence is also a time of cognitive, social and emotional changes.
PRIMARY SEXUAL CHARACTERS – Primary sexual characteristics include the reproductive organs an individual is born with. Testes in male and ovaries in females.
PUBERTY – Puberty is the period of life during which a person attains reproductive maturity. During puberty, the person’s body undergoes changes – development of the reproductive organs and secondary sexual characteristics.
TEENAGE- The period of life between the ages 13 and 19 is known as the teenage years. It is also the period of adolescence – the transitional period between childhood and adulthood.
REPRODUCTIVE MATURITY/ SEXUAL MATURITY – Reproductive maturity is the ability of an organism to reproduce.
SEBACEOUS GLAND – It is a gland located in the dermis layer of the skin, which secretes an oily, waxy substance known as sebum.
DERMIS– The dermis is one of the layers of the skin.
SECONDARY SEXUAL CHARACTERS – Secondary sexual characteristics are those which emerge at puberty and help us differentiate a male and female by appearance. Change of body shape and height are some examples of secondary sexual characteristics.
ENDOCRINE GLANDS – Endocrine glands are known as ductless glands. They secrete hormones directly into the bloodstream. Eg: Adrenal glands, Thyroid, gonads
EXOCRINE GLANDS – Exocrine glands are glands with ducts that secrete substances/chemicals into a duct which reaches the target sites. Eg: Salivary glands, mammary glands
GAMETES – Gametes are also called sex cell/reproductive cells. They are distinct in males and females. The male gamete is called sperm whereas the female gamete is called ovum (Plural – Ova) or egg. Gametes are formed in the reproductive organs. During sexual reproduction, the male and female gametes fuse (fertilization) to form the zygote.
GROWTH HORMONE – Growth hormone is produced by the pituitary gland. It promotes the growth of individuals.
GIGANTISM – It is a growth hormone related disorder. It is the result of the excess secretion of growth hormone by the pituitary gland. In children it is known as gigantism wherein in adults this condition is called acromegaly.
DWARFISM – It is a growth hormone related disorder. It occurs due to insufficient secretion of growth hormone by the pituitary gland in children.
GOITRE – Goiter is a swelling of the thyroid gland that is visible in the neck region. Simple goitre is caused because of insufficient secretion of thyroxine which is a hormone produced by the thyroid gland.
HOARSE – When a person’s voice sounds rough and harsh, it is said that their voice is hoarse.
HORMONES – Hormones are chemicals that are secreted by the endocrine glands. They are also called chemical messengers. They are concerned with maintaining various body functions.
- Thyroxine hormone is secreted by the thyroid gland,this hormone maintains body metabolism.
- Insulin is secreted by the pancreas, this hormone maintains blood glucose levels.
INSULIN – Insulin is a hormone that is secreted by pancreas. It helps in maintaining the blood glucose level.
IODINE – Iodine is a mineral found in some foods. The body needs iodine to make thyroid hormone. This hormone controls the body’s metabolism and many other important functions.
MAMMARY GLAND – Mammary gland is an exocrine gland found in mammals. It is concerned with the production of milk after a young one is born in order to feed them.
MENARCHE – In girls, menstruation starts usually between the age of 10 to 15 when they attain puberty. The occurrence of menstruation for the first time is called menarche.
MENOPAUSE – The term menopause is used to describe the end of a woman’s menstrual cycle and the different changes a woman experiences. This marks the end of the reproductive phase of a female. Menopause happens after the age of 40 and may also vary from person to person.
MENSTRUAL CYCLE – Reproductive cycle involving a series of changes in the ovary and the uterus preparing for a possible pregnancy in a woman’s body every month is called the menstrual cycle.
MENSTRUATION – When the released ovum is not fertilized by a sperm, the egg, the inner lining of the uterus along with the blood vessels are shed periodically (once in 28 – 30 days). This is called menstruation and is a part of the menstrual cycle.
METAMORPHOSIS – The transformation of the larva into an adult through drastic changes is called metamorphosis. Frogs and insects are examples of organisms showing metamorphosis.
NUCLEUS – The nucleus is a double-membraned organelle that contains the genetic material.
OESTROGEN and PROGESTERONE – Oestrogen and progesterone are hormones produced by the ovaries. Progesterone plays an important role in the menstrual cycle and maintenance of pregnancy. Oestrogen is responsible for the development of secondary sexual characters and is also involved in maintaining the menstrual cycle and pregnancy.
OVARY – Ovaries act as the main female sex organs that produce the female gametes and various hormones. These organs are situated one on both sides of the lower abdomen.
OVUM ( EGG) – Ovum is the female reproductive cell (female gamete). Plural : Ova.
PIMPLE – Pimples are tiny bumps on skin caused due to the increased activity of the sweat and sebaceous gland.
ACNE – Acne is a skin condition in which the sebaceous glands get inflamed due to hormonal imbalance. This condition arises in most teenagers because of the hormonal changes in the body. It usually goes after the adolescence period.
ADAM’S APPLE – Adam’s apple develops during puberty and is prominent in males. It is visible as a protrusion in the throat due to the enlargement of the voice box.
VOICE BOX/LARYNX – Voice box, also called a larynx, is an organ situated in the neck region above the windpipe/trachea. It contains vocal cords which manipulate the pitch and volume of the voice.
ADDICTION – The term addiction is defined as a disorder characterized by uncontrollable drug seeking and use of it, despite its adverse consequences.
ADRENALINE – It is a hormone secreted by the adrenal glands. This hormone helps our body respond to stress by bringing about certain changes in the body like increasing the heart rate, raising blood glucose levels, etc. It is also called the ‘fight or flight’ hormone.
HIV – Human Immunodeficiency Virus (HIV) causes AIDS.
AIDS – Acquired immunodeficiency syndrome (AIDS) is a disease caused by the Human Immunodeficiency Virus (HIV). It is a chronic condition where the immune system of the person is severely damaged. It spreads through infected needles, sexual contact with the infected person, it is known to spread from infected mother to baby during pregnancy. AIDS does not spread through touch. There are many medications to manage the symptoms but currently, there is no cure for AIDS.
- The thread-like structure present inside the nucleus is called chromatin. Chromatin condenses to form the X-shaped structure called chromosomes ( looks like an ‘X’ ) during cell division. (Cell division is a biological process by which one cell divides into two or more cells).
- In human beings there are 46 (23 pairs) chromosomes. Each chromosome is made of proteins called histone and DNA (DNA-Deoxyribonucleic acid).
DIABETES – Diabetes is a disease in which the glucose levels in the blood will be high over a prolonged period of time. Insulin secreted by pancreas helps in reducing the blood sugar level. This disease occurs either when insulin is not produced in enough amounts or if the produced insulin is not utilised by the body effectively.
DNA – DNA (Deoxyribonucleic acid)is the genetic material in most organisms including human beings. DNA is present inside the nucleus which has information to make proteins in our body.
DRUGS – Drugs are chemical substances that are used as medication or in the preparation of medication. This term also refers to the substances that cause addiction.
SEX CHROMOSOME ( ALLOSOME) – In humans, a normal cell contains 23 pairs (46) of chromosomes. Out of these, one pair is sex chromosomes, which helps in the determination of the biological sex of an individual. They are named X and Y chromosomes. Male will have one ‘X’ and one ‘Y’ chromosome while a female will have 2 ‘X’ chromosomes.
SPERM – Sperm is the male reproductive cell (male gamete) produced by testes.
TESTES – It is the male reproductive organ which produces the male gametes (sperms). It occurs in pairs in humans. It also produces the male sex hormone – testosterone.
TESTOSTERONE – Testosterone is a sex hormone that is secreted by the testes. It is involved in the development of male reproductive organs and secondary sexual characteristics .
THYROXINE – Thyroxine is a hormone secreted by the thyroid gland. It maintains the balance of all metabolic activities. The deficiency of this hormone can cause swelling of the thyroid gland, leading to goiter.
Reproduction – Reproduction is the process of producing individuals of the same kind. It is important for the continuation of life on earth.
Growth – It refers to the increase in height or size of the body or body parts.
Childhood – It is the period in an individual’s life span when all the body parts are at their developing stage.
Growth spurt – Growth spurt is referred to as the sudden increase in growth of the body. It lasts for 2-3 years and is most active during the adolescence period.
Sweat gland – It is a gland located in the dermis layer of the skin, which secretes sweat.
Gonadotropin releasing hormone – GnRH – The Gonadotropin releasing hormone is produced by hypothalamus. It regulates the secretion of luteinizing hormone and follicle stimulating hormone from the pituitary gland.
Pituitary gland – The pituitary gland is an endocrine gland situated in the brain and is called a master endocrine gland. It produces hormones that instruct other glands to secrete their hormones, this is why it is also called ‘master gland’. It also secretes growth hormone which controls the overall growth of a person.
Luteinizing hormone and Follicle stimulating hormone – Luteinizing hormone (LH) and Follicle stimulating hormone (FSH) are collectively known as gonadotropins, which are secreted by the pituitary gland. LH and FSH control the sexual and reproductive characteristics in males and females.
Adrenal gland – The adrenal glands are endocrine glands that are situated right above the kidneys. Adrenal glands produce hormones like adrenaline.
Thyroid gland – Thyroid gland is a butterfly-shaped endocrine gland situated in the throat. It secretes a hormone called thyroxin. This hormone is important as it maintains the balance of all metabolic activities. The deficiency of this hormone can cause swelling of the thyroid gland, leading to goiter.
Gonads – Gonads are organs that produce gametes. In males, testes produce sperms (male gametes) and in females, the ovaries produce eggs (female gametes). They are also responsible for producing sex hormones (Eg: Estrogen and Teststerone).
Gendercide – Gendercide is the killing of individuals of a specific gender. This inhuman act is practiced in many parts of the world against female infants and this should be abolished.
Ovulation – Ovulation is the process of release of a mature egg from one of the ovaries, which happens every month.