Class 8 Biology Chapter 5 Endocrine System and Adolescence Notes

KSEEB Solutions for Class 8 Biology Chapter 5 Endocrine System And Adolescence Learning Objectives

Endocrine System Two types of glands-Exocrine and endocrine (basic concept and difference); Hormone (definition). Hormonal glands -(thyroid, adrenal, pancreas, pituitary): location and function of each. The following points to be studied in tabular form: name of gland, location in body, secretion, function Adolescence Physical and emotional changes in the body during adolescence. Importance of personal hygiene. Stress management (meaning of stress; ways to tackle stress: yoga, meditation, time management, sports, hobbies, rational thinking etc.)
A gland is a structure that secretes a specific substance (or substances) in the body. Though you have many glands throughout your body they fall into two types-endocrine glands and exocrine glands.

KSEEB Solutions for Class 8 Biology Chapter 5 Endocrine System and Adolescence Notes

Endocrine And Exocrine Glands

A gland which secretes its product into a duct (or tube) is called an exocrine gland. For example, the salivary gland secretes its product (saliva) into a duct called ‘salivary duct’, therefore, salivary gland is an exocrine gland. Sweat glands and sebaceous glands (or oil glands) are also exocrine glands which release their secretions through ducts. A gland which does not have a duct and secretes its product directly into the blood stream, is called an Pituitary gland Thyroid gland Thymus Adrenal gland Kidney Pancreas endocrine gland.
An endocrine gland makes (and secretcs) a chemical substance called ‘hormone’ Some of the examples of endocrine glands (or ductless glands) in our body are pituitary gland, thyroid gland and adrenal glands. Some of the glands in our body function both, as endocrine glands as well as exocrine glands.

Endocrine system and adolensence endocrine glands

For example, pancreas, testes and ovaries. Endocrine glands release their hormones directly into the blood stream of a person. These hormones reach the concerned body part (called target site) through the blood and act on it. Ovary (in females) Testes (In males)

Endocrine system and adolensence differences between exocrinne and endocrine glands

Hormones

Hormones are the chemical substances which co-ordinate the activities of living organisms and also their growth. Hormones are made and secreted by specialised tissues in the body called ‘endocrine glands’ The hormones are poured directly into the blood and carried throughout the body by the blood circulatory system. The hormones act on ‘specific tissues’ or ‘specific organs’ in the body called ‘target sites’.
A hormone is produced by an endocrine gland in one part of human body but causes a particular effect in another part of the body. Hormones are of many different types and perform different functions in the body. The hormones involved in the development and control of the reproductive organs and secondary sexual characteristics are called sex hormones. The two common sex hormones are testosterone and estrogen (Estrogen is also spelled as oestrogen).

Endocrine System

A group of endocrine glands which produces various hormones is called an endocrine system. The endocrine system in our body consists of a number of glands (or tissues) which make, store, and release hormones. There are a large number of endocrine glands in the human body. The endocrine glands present in the human body are: Pineal gland, Hypothalamus gland, Pituitary gland. Thyroid gland, Parathyroid glands, Thymus, Pancreas, Adrenal glands, Testes (only in males) and Ovaries (only in females).

Class 8 Biology KSEEB Endocrine System And Adolescence Notes

Thyroid Gland (or Thyroid)

Thyroid is a large endocrine gland in the neck. It is attached to the wind pipe in our body. Thyroid gland makes a hormone called Larynx thyroxine (which contains iodine).
Thyroid gland secretes its hormone (thyroxine) when it receives instructions from the pituitary gland through its hormones. Thyroxine hormone controls the rate of body’s metabolism. Thyroid gland needs a constant supply of iodine in order to produce thyroxine hormone. A deficiency of iodine in the diet can cause a deficiency of thyroxine hormone in the body. Pancreas acts as an endocrine gland as well as an exocrine gland.

Endocrine system and adolensencethyroid gland

Goitre: The main symptom of goitre disease is that the neck of the person suffering from goitre appears to be swollen. The person appears to have a big and bulging neck.
Iodised salt can provide all the iodine needed by thyroid gland to make sufficient thyroxine hormone for our body.

Endocrine system and adolensence a person suffering from goitre

Pituitary Gland

Pituitary gland is attached to the base of the brain. The pituitary gland secretes a number of hormones. One of the hormones secreted by pituitary gland is the growth hormone or human growth hormone. This hormone controls the growth of the human body. For example, growth hormone controls the development of bones and muscles. Proper amount of growth hormone is necessary for the normal growth of the body.
A person having the deficiency of growth hormone in childhood remains very short and becomes a dwarf. The deficiency of the growth hormone leads to dwarfism in children. On the other hand, a person having loo much growth hormone becomes very tall (or a giant). Overactivity of the growth hormone leads to gigantism in the young and acromegaly in the adults (gorilla¬like appearance). Pituitary gland is the most important endocrine gland in the body.
It is called ‘master gland’ because many of the hormones which it secretes control the functioning of other endocrine glands in the body. For example, pituitary gland secretes hormones that make other endocrine glands such as testes, ovaries, thyroid gland, and adrenal glands to secrete their hormones.

Endocrine system and adolensence location of pitutary glands in humans

Some of the major hormones produced by pituitary gland in the human body arc:

Growth hormone which regulates the growth and development of the body parts.
It produces the hormones which regulates the production of sperms in males and ova in females.
It also produces hormones which cause the muscles of the uterus to contract in case of child birth, thereby helping in birth process.

Adrenal Glands

There are two adrenal glands which are located oil the lop of two kidneys. The adrenal glands secrete adrenaline hormone.
The function of adrenaline hormone is to regulate heart rate, breathing rate, blood pressure and carbohydrate metabolism.

Endocrine system and adolensence kidneyPNG

Adrenaline hormone is secreted in small amounts all the time but in large amounts when a person is frightened or excited. When adrenaline is secreted in large amounts it prepares our body for action. It speeds up heart beat and breathing, raises blood pressure and allows more glucose (carbohydrate) to go into the blood to give us a lot of energy quickly to fight or flight (run away). Adrenal glands are often called glands of emergency’.

KSEEB Class 8 Biology Solutions For Endocrine System And Adolescence

Pancreas

Pancreas is just below the stomach in our body. Pancreas secretes the hormone called insulin.
The function of insulin hormone is to lower the blood sugar level (or blood glucose level). Deficiency of insulin hormone in the body causes a disease known as diabetes. Diabetes is characterised by higher level of sugar in the blood and even urine. The insulin hormone controls the metabolism of sugar. If, due to some reason, pancreas does not produce and secrete sufficient amount of insulin into blood, then the sugar level in the blood rises. The high sugar level in the blood can cause many harmful effects to the body of a person. The person having high sugar level in blood (or diabetes) is called a diabetic.
Diabetic persons are advised by doctors to take less sugar in their diet. Common diabetes can be controlled by controlling diet, reducing weight, doing regular physical exercise and taking medicines. The persons having severe diabetes are treated by giving injections of insulin. Pancreas also secrete glucagon which stimulates the breakdown of glycogen into glucose in the liver.

Endocrine system and adolensence pancreasPNG

Endocrine system and adolensence some endocrine glands

Adolescence

There is a period of life in human beings when a person is neither a child nor an adult. The transitional period of physical and mental development which occurs between childhood and adulthood is called adolescence. In most simple words, the period of life between childhood and adulthood is called adolescence. It occurs from an age of about 12 to 20 years. This period covers the teenage, (thirteen to nineteen) hence adolescents are also called teenagers.
Adolescence is the time when a lot of changes take place in the bodies of boys and girls which make their reproductive systems ‘mature’.
During adolescence, the body undergoes a lot of different kinds of physical and mental changes.
An adolescent experiences social, emotional, cognitive and physical changes. These changes indicate the start of puberty in adolescence. At puberty, sex hormones (or gametes) begin to be produced due to which the boys and girls become sexually mature. The period during which adolescent boys and girls reach sexual maturity’ and become capable of reproduction is called puberty.

Endocrine System And Adolescence Class 8 KSEEB Questions And Answers

Physical Changes During Adolescence

The human body undergoes many changes during adolescence. During this phase, teenagers (both boys as well as girls) experience a lot of changes in their body shape, size, voice, etc. Some of them may grow suddenly as puberty’ approaches whereas some of them show slow changes and developments. Hormonal secretions from endocrine glands play an important role in the physical growth of adolescents.
The most conspicuous change is the sudden increase in the height of boys and girls. Pituitary gland produces growth hormone that leads to the growth of arms and legs and makes a person look tall. A rise in the growth hormone produces a sudden increase in height and weight of both the sexes. Initially, girls grow faster than boys but by about 18 years of age, both reach their maximum height. Ail the parts of the body do not grow’ at the same rate. Sometimes the arms and legs, or hands and feet of adolescent boys and girls look oversized and out of proportion with the body.
But soon the other parts catch up with them in growth. This results in a more proportionate body. The rate of growth in height varies in different individuals. Some of them may grow suddenly at puberty’ and then slow’ down, while others may grow slowly and attain their maximum height.
The given table indicates the average rate of growth in height of boys and girls between the ages of 12 to 14 years.

Endocrine system and adolensence average height growth in boys and girls

If w’e know the present height of a person (boy or girl) and the percentage of his (or her) full height at present age, we can calculate the full height of the person which he (or she) will eventually reach. This can be done by using the formula:

Change in Body Shape and Appearance

When puberty sets in, a time of rapid changes in body shape and appearance starts in boys and girls which make the boys and girls look different from one another. Actually, testes in boys and ovaries in girls make different hormones which make the bodies of boys and girls to develop in different ways.
So, the changes in body shape occurring in adolescent boys and girls at puberty are different. In boys, generally the muscles of the body grow more prominently than in the girls. Their shoulders generally broaden more, whereas, in girls, the region below the waist becomes wider.

Change in Voice

At puberty, the voice box (or larynx) begins to grow in boys as well as in girls. You must have noticed that the voice of an eight-year old child is different than your voice of a fourteen year old child. This is because, at puberty, the voice box or the larynx in males starts growing.
The bulge (or projection) at the front of throat or neck in grown up boys is called Adam’s Apple. Unlike boys, in girls, the larynx does not grow that large in size and hence it is hardly visible in the throat. Usually, the voice in girls develops to be high pitched, whereas boys develop a deep or hoarse voice.

Development of Sex Organs and Secondary Sexual Characters

The onset of puberty brings about complete growth and development of sex organs in boys and girls due to which their reproductive systems start functioning at this stage. In boys, the testes, penis and scrotum grow in size rapidly. Boys also develop facial, pubic and body hair. In girls, breasts start developing as the mammary glands or milk-producing glands also grow and develop. They also experience change internally as the uterus, vagina, and other parts of the reproductive system start to grow.
During this period, the girls start their first menstrual period called menarche. This marks the beginning of reproductive phase in females which make girl capable of bearing a baby.
In boys, there is higher production of male sex hormone also called testosterone. Whereas, in girls there is an increase in the production of the female sex hormone known as oestrogen. These hormones also help to develop characteristics also called secondary sexual characters.

Emotional Changes during Adolescence

Adolescence continues up to the age of 18 or 19 years. During adolescence, a boy (or girl) reaches mental, intellectual and emotional maturity.
At this stage, adolescent boys and girls spend considerable time thinking about many things occurring in their minds. During adolescence, mental maturity makes the boys and girls more independent than before. They want to take hold of their life and decision-making capacity. They often develop mistrust for adults or family members and tend to make wrong decisions. Most adolescents start developing a distance from their parents and find opinions of their friends more convincing. They start getting influenced by the lifestyle their peer have, what they wear etc.
The changes which occur in the body of boys and girls during adolescence may cause emotional swings. These emotional swings show intense feelings such as joy, anger, boredom, worries or sadness winch are not based on reasoning or knowledge. The adolescents also become self¬conscious (unduly aware of ones actions leading
to nervousness). Sometimes, the adolescents feel insecure (not confident) while trying to adjust to the changes in body and mind. There is, however, no reason to feel insecure. The changes which take place in body and mind during adolescence are a natural part of the growing up process.

Personal Hygiene For Adolescents

Keeping our body clean is called personal hygiene. The maintenance of personal hygiene (or cleanliness) is necessary for adolescents for preventing diseases and keeping good health. The adolescents can maintain personal hygiene by adopting the following practices:
Adolescent should take bath regularly (at least once every day). Though having bath is good for everyone, it is more necessary for adolescents (or teenagers) because the increased activity of sweat glands and oil glands sometimes makes the body smelly. Bathing removes the sweat, oil and dirt, etc., and cleans the body.
Adolescent girls should take special care of cleanliness of the body during the time of menstrual flow (or periods). The girls should keep a track of their menstrual cycle and be prepared for the onset of menstruation. If personal hygiene (or cleanliness of body) is not maintained by adolescent boys and girls, there arc chances of catching bacterial infections. These infections can make a person ill and spoil good health.

Explanation Of Endocrine System In KSEEB Class 8 Biology

Stress Management

Adolescence is a period of much activity in the body and mind of young boys and girls. Sometimes an adolescent boy or girl undergoes emotional swings such as feeling confused, insecure, bored, worried, stressed out, tense or angry, etc. But there is nothing to feel stressed about.
They need to understand that all these changes are part of their growth and development.
Many limes, due to peer pressure or misguidance, adolescents are lured to do drugs. Drugs are chemical substances which when taken into the body change the functions of the body, influence the mind and sometimes even change the behaviour of the person. Drugs destroy mental and emotional development and makes the user addictive. Therefore, always stay away from these chemical substances and report about any person who approaches you with the idea of drugs.
Mostly, adolescents feel stressed during examination or to balance studies and recreational activities. Time management should be adopted to deal with such type of stress or pressure. Priorities should be set according to the need of the hour. There has to be balance in life—personal and studies, hobbies and social life, etc.
All the adolescent boys and girls should do physical exercise such as brisk walking, jogging or running, swimming, cycling, dancing, and playing outdoor games regularly. Yoga and meditation is another way of dealing with any kind of stress. It boosts the confidence and maintains physical and mental health. Physical exercise such as yoga, dance, and any kind of sports play a significant role in dealing with any kind of stress.

Summary

Glands are structures made up of cells and release some substances.
Hormones regulate the growth and development of the body.
The exocrine glands directly send the secretions to the organs through specified ducts. Endocrine glands are ductless and they send their secretion (called hormones) in the blood vessels through v/hich they reach the organs.
Some of the important endocrine glands are thyroid, adrenal, pancreas and pituitary gland.
The age between 13 to 19 is known as teenage. Adolescence age begins from about 12 years to 20 years.
During adolescence, boys and girls experience lot of changes in their body shape, size, voice, etc.
Puberty marks the onset of reproductive phase and development of sexual characteristics in both males and females. All these characteristics are also called secondary sexual characters.
Since there are a lot of physical changes taking olace during adolescence, it becomes extremely important to maintain personal hygiene.
Adolescents needs to continuously talk to their parents or teachers about how they feel and share any problem that they may be facing.

Part A – Our PASTS – III (History)

Part B – Resources and Development (Geography)

Part C: Social and Political Life -III (Civics)