Endocrine System and Adolescence ICSE Class 8: Glands, Hormones, Changes at Adolescence and Managing Stress

What Endocrine System and Adolescence is about

Weightage: CISCE publishes no question paper, marking scheme or chapter weightage for Class VIII Biology: your school sets and marks the exam. Endocrine System and Adolescence sits in the Theme: Human Body - Endocrine, Circulatory and Nervous Systems theme of the CISCE Curriculum for Upper Primary Classes (VI-VIII).Source: CISCE Curriculum for Upper Primary Classes (VI-VIII), RDCD 2016

Key concepts

Exocrine and endocrine glands

A gland is an organ or group of cells that makes and releases (secretes) a useful substance.

	Exocrine glands	Endocrine glands
Ducts	have ducts (tubes)	ductless
Secretion goes	through the duct to a particular place	directly into the blood
Secretion	enzymes, sweat, saliva, tears, oil	hormones
Examples	salivary glands, sweat glands, tear glands, gastric glands	thyroid, adrenal, pituitary

Pancreas is both: it is a mixed (heterocrine) gland. Its exocrine part sends pancreatic juice (digestive enzymes) through a duct into the small intestine; its endocrine part, small groups of cells called the islets of Langerhans, releases insulin into the blood.

All endocrine glands together form the endocrine system.

Worked example

Why is the pancreas called a mixed gland?

Try it first, then show the solutionSolution

1. Its exocrine part secretes pancreatic juice through a duct into the duodenum.
2. Its endocrine part (islets of Langerhans) secretes insulin directly into the blood.

Answer: It works both as an exocrine and as an endocrine gland.

Hormones

A hormone is a chemical messenger secreted by an endocrine gland directly into the blood, which carries it to a target organ where it produces a particular effect.

Features of hormones:

• They act in very small amounts.
• They travel through the blood, so their effects are slower but often longer-lasting than nerve messages.
• Each hormone acts on particular target organs.
• Too much (hypersecretion) or too little (hyposecretion) of a hormone causes disorders.

Comparing the two control systems:

Nervous control	Hormonal control
electrical impulses along nerves	chemicals in the blood
very fast	slower
short-lived effect	usually longer-lasting effect

Worked example

Give two differences between a nerve message and a hormone.

Try it first, then show the solutionSolution

1. A nerve message is an electrical impulse along a nerve; a hormone is a chemical carried in blood.
2. A nerve message is very fast and short-lived; a hormone acts more slowly and its effect usually lasts longer.

Answer: Electrical vs chemical; fast and short vs slow and longer-lasting.

Thyroid and adrenal glands

Gland	Location	Secretion	Function
Thyroid	in the neck, in front of the windpipe (trachea), just below the voice box; shaped like a butterfly	thyroxine	controls metabolism (the rate at which the body uses food to release energy); needed for normal growth and development of body and brain
Adrenal (a pair)	on top of each kidney, like a cap	adrenaline	prepares the body for emergencies ('fight or flight'): faster heartbeat and breathing, more sugar in the blood, more blood to muscles

Thyroid and iodine: thyroxine contains iodine. If the diet lacks iodine, the thyroid enlarges, causing a swelling in the neck called goitre. Using iodised salt prevents it.

Adrenaline in action: when you are suddenly frightened (a dog barks behind you) or tense before a race, your heart pounds and you breathe fast. That is adrenaline getting your muscles ready to run or fight. It is called the emergency hormone.

Worked example

A person living in a hilly area far from the sea has a swollen neck. Name the gland, the condition and a simple way to prevent it.

Try it first, then show the solutionSolution

1. The thyroid gland in the neck is enlarged: goitre, due to lack of iodine for making thyroxine.
2. It can be prevented by using iodised salt.

Answer: Thyroid; goitre; iodised salt

Pancreas and pituitary

Gland	Location	Secretion	Function
Pancreas (islets of Langerhans)	in the abdomen, behind the stomach, in the loop of the duodenum	insulin (and glucagon)	insulin lowers blood sugar: it helps cells take in glucose and the liver store extra glucose as glycogen; glucagon raises blood sugar when it falls
Pituitary	at the base of the brain, a pea-sized gland	growth hormone, and hormones that control other glands	growth hormone controls the growth of bones and muscles; other pituitary hormones control the thyroid, adrenals, testes and ovaries

Diabetes: when the pancreas makes too little insulin, blood sugar stays high and sugar appears in the urine. This is diabetes mellitus. It is managed by diet, exercise and, when needed, insulin injections.

Master gland: the pituitary is called the master gland because its hormones control the working of several other endocrine glands.

Growth hormone disorders: too much in childhood causes gigantism (very tall); too little causes dwarfism (very short, though well proportioned).

Worked example

Why is the pituitary called the master gland? Name one disorder caused by too little of its growth hormone in childhood.

Try it first, then show the solutionSolution

1. Its hormones control the activities of other endocrine glands such as the thyroid, adrenals and sex glands.
2. Too little growth hormone in childhood causes dwarfism.

Answer: It controls other glands; dwarfism.

Adolescence: physical changes

Adolescence is the period of life between childhood and adulthood, roughly from 11 to 19 years (the 'teens'). Puberty is the stage at the start of adolescence when the body becomes capable of reproduction.

The changes are triggered by hormones: the pituitary signals the testes to make testosterone in boys and the ovaries to make oestrogen in girls.

Changes in both boys and girls:

• A growth spurt: a sudden increase in height and weight.
• Hair grows in the armpits and pubic region.
• Sweat and oil glands become more active, which can cause body odour and pimples (acne).

Changes in boys:

• The voice box (larynx) grows, forming the Adam's apple, and the voice deepens (it may 'crack' for a while).
• Hair grows on the face (moustache, beard) and chest.
• Shoulders broaden and muscles develop.
• The testes start producing sperms.

Changes in girls:

• Breasts develop and hips widen.
• Menstruation (periods) begins; the ovaries start releasing eggs.
• The voice becomes slightly higher and clearer.

These changes start at different ages in different people; girls often begin a year or two earlier than boys. All of this is normal.

Worked example

List two changes common to boys and girls at adolescence and one change specific to each.

Try it first, then show the solutionSolution

1. Common: growth spurt; hair in armpits and pubic region (or more active sweat and oil glands).
2. Boys: voice deepens (Adam's apple). Girls: breasts develop (or menstruation begins).

Answer: As above

Emotional changes, hygiene and stress

Emotional changes in adolescence:

• Mood swings: happy one moment, upset the next.
• A wish for independence and to make one's own decisions; sometimes conflict with parents.
• Being self-conscious about one's looks and body.
• Strong influence of friends (peer pressure).
• Curiosity, new interests and attraction towards others.

Personal hygiene matters more now because sweat and oil glands are more active:

• Bathe daily and wear clean clothes and undergarments, dried in the sun.
• Wash your face to keep pores clear; do not squeeze pimples.
• Use deodorant if needed; keep hair and nails clean.
• Girls should change sanitary pads regularly during periods and wash properly.
• Brush teeth twice a day; eat a balanced diet with protein, iron and calcium for the growth spurt; drink water and sleep 8 to 9 hours.

Stress is a feeling of mental or emotional pressure or tension when we face a difficult or demanding situation, such as exams, peer pressure or arguments. A little stress can push us to work; too much harms sleep, appetite, health and studies.

Ways to tackle stress:

• Yoga and meditation: calm the mind and slow breathing.
• Time management: plan study with breaks so work does not pile up.
• Sports and exercise: release tension and improve mood.
• Hobbies: music, art, reading, gardening.
• Rational thinking: look at the problem calmly and break it into small steps.
• Talk to parents, teachers or friends you trust; sleep well.

Avoid harmful ways of 'coping', such as tobacco, alcohol or drugs.

Worked example

A Class 8 student feels nervous, cannot sleep and skips meals before exams. Suggest three ways to manage this stress.

Try it first, then show the solutionSolution

1. Make a study timetable with short breaks (time management).
2. Do some exercise or yoga daily, and a few minutes of slow breathing or meditation before bed.
3. Talk to a parent or teacher, and eat and sleep on time.

Answer: Time management; yoga, meditation or sport; talking to a trusted adult (any three valid).

Endocrine System and Adolescence in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Adolescence: Changes, Personal Hygiene and Stress Management
• Exocrine and Endocrine Glands, Hormones and the Four Hormonal Glands

Endocrine System and Adolescence: key facts

Hormone route

$\text{endocrine gland}\to \text{blood}\to \text{target organ}$

No duct; tiny amounts.

Thyroid

$\text{thyroid (neck)}\to \text{thyroxine}\to \text{metabolism, growth}$

Needs iodine; lack causes goitre.

Adrenal

$\text{adrenal (on kidneys)}\to \text{adrenaline}\to \text{fight or flight}$

Emergency hormone.

Pancreas

$\text{islets of Langerhans}\to \text{insulin}\to \text{lowers blood sugar}$

Too little: diabetes.

Pituitary

$\text{pituitary (base of brain)}\to \text{growth hormone}+\text{controls other glands}$

Master gland.

Endocrine System and Adolescence: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

How the school exam asks Endocrine System and Adolescence

The question patterns to expect, and the method that works for each.

Tricks to remember Endocrine System and Adolescence

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Ex = Exit through a tube; Endo = into the blood within

  Exocrine glands have an exit duct; endocrine glands send hormones within, into the blood.

  Use it when: Exocrine versus endocrine.

• Please Take A Pill (head to abdomen)

  Pituitary (head), Thyroid (neck), Adrenal (on kidneys), Pancreas (abdomen, behind the stomach): 'Please Take A Pill'.

  Use it when: Locations of the four glands from head down.

• Thyroxine = throttle

  Thyroxine sets the speed of the body's engine (metabolism).

  Use it when: Function of the thyroid.

• Adrenaline = alarm

  The alarm hormone: heart races, breath quickens, ready to run.

  Use it when: Function of the adrenal glands.

• Insulin lets sugar IN

  Insulin lets glucose into cells and storage, lowering blood sugar.

  Use it when: Function of insulin.

Endocrine System and Adolescence: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section B style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 6-mark question split into 2 + 2 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Endocrine System and Adolescence

The slips examiners see most often, and what to write instead.

• ✗Mistake: Saying hormones travel through ducts

  Endocrine glands are ductless; hormones go directly into the blood.

  ✓Do this: Endocrine = ductless = into blood.

  Usually costs: 1 mark.

• ✗Mistake: Placing the adrenal glands on the brain or the pancreas in the neck

  Adrenals sit on top of the kidneys; the pancreas is in the abdomen behind the stomach.

  ✓Do this: Learn the head-to-abdomen order: pituitary, thyroid, adrenals, pancreas.

  Usually costs: 1 mark per location.

• ✗Mistake: Saying insulin raises blood sugar

  Insulin lowers blood sugar; glucagon raises it.

  Wrong working

  Diabetes is caused by too much insulin

  Right working

  Diabetes is caused by too little insulin

  ✓Do this: Insulin lets sugar IN to cells.

  Usually costs: 1 mark.

• ✗Mistake: Writing that adolescence happens at the same age for everyone

  It begins at different ages; girls often start earlier than boys.

  ✓Do this: Say 'roughly 11 to 19 years' and 'varies from person to person'.

  Usually costs: 1 mark.

• ✗Mistake: Listing only 'study more' for stress management

  Stress management is about relaxing and organising, not adding pressure.

  ✓Do this: Name specific methods: yoga, meditation, time management, sports, hobbies, rational thinking.

  Usually costs: 1-2 marks.

Practice questions on Endocrine System and Adolescence

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQExam level

   Adrenal glands are located:
   (a) in the neck
   (b) at the base of the brain
   (c) on top of the kidneys
   (d) behind the stomach

   Hint

   Ad-renal: renal means kidney.

   Answer

   (c)

2. Q2 · 1 mark · Very short answerExam level

   Name the hormone whose deficiency causes diabetes.

   Hint

   From the pancreas.

   Answer

   Insulin.

3. Q3 · 2 marks · Short answerExam level

   State two functions of thyroxine.

   Hint

   Metabolism and growth.

   Answer

   It controls the rate of metabolism (release of energy from food) and is needed for normal growth and development of the body and brain.

4. Q4 · 2 marks · Short answerExam level

   Give two physical changes seen only in boys and two only in girls during adolescence.

   Hint

   Voice, beard; breasts, periods.

   Answer

   Boys: voice deepens (Adam's apple); facial hair grows (or broad shoulders). Girls: breasts develop; menstruation begins (or hips widen).

5. Q5 · 1 mark · Assertion-reasonHarder exam level

   Assertion (A): The pancreas is called a mixed gland.
   Reason (R): The pancreas secretes digestive juice through a duct and insulin directly into the blood.
   (a) (A) is true and (R) is false.
   (b) (A) is false and (R) is true.
   (c) Both (A) and (R) are true, and (R) is the correct explanation for (A).
   (d) Both (A) and (R) are true, but (R) is not the correct explanation for (A).

   Hint

   Exo + endo.

   Answer

   (c)

6. Q6 · 2 marks · Short answerHarder exam level

   What happens if the pituitary secretes too much growth hormone in childhood? Too little?

   Hint

   Giants and dwarfs.

   Answer

   Too much causes gigantism (abnormally tall); too little causes dwarfism (abnormally short but well proportioned).

7. Q7 · 2 marks · Short answerHarder exam level

   List four effects of adrenaline on the body.

   Hint

   Heart, lungs, sugar, muscles.

   Answer

   Faster heartbeat; faster breathing; more glucose in the blood; more blood sent to muscles (also pupils widen).

8. Q8 · 3 marks · Short answerHarder exam level

   Why is personal hygiene especially important during adolescence? Give three hygiene practices.

   Hint

   Sweat and oil glands.

   Answer

   Sweat and oil glands become more active, causing body odour and pimples, and infections can follow. Practices: bathe daily and wear clean, sun-dried clothes; wash the face gently and do not squeeze pimples; girls change sanitary pads regularly (also brush teeth twice a day).

9. Q9 · 2 marks · Short answerHarder exam level

   Distinguish between nervous control and hormonal control (two points).

   Hint

   Electrical vs chemical.

   Answer

   Nervous control uses electrical impulses along nerves and is very fast but short-lived; hormonal control uses chemicals carried by blood and is slower but usually longer-lasting.

10. Q10 · 3 marks · Short answerHarder exam level

    Explain how rational thinking and time management help reduce stress, with an example of each.

    Hint

    Look calmly; plan.

    Answer

    Rational thinking: looking at a problem calmly and realistically, e.g. 'one bad test does not decide my whole year; I will revise the topics I got wrong.' Time management: planning tasks with breaks so work does not pile up, e.g. a study timetable starting two weeks before exams.

11. Q11 · 2 marks · Short answerHarder exam level

    A student's height went from 142 cm to 150 cm in one year and to 156 cm the next. Find the growth in each year and the average yearly growth. Name the stage and the gland mainly responsible.

    Hint

    Subtract, then average.

    Answer

    8 cm in the first year and 6 cm in the second; average (8 + 6) ÷ 2 = 7 cm per year. This is the adolescent growth spurt, controlled mainly by growth hormone from the pituitary.

12. Q12 · 3 marks · Short answerHOTS / competency

    An athlete feels her heart race and her breathing quicken just before a race, though she is standing still. Explain this in terms of hormones, and why it is useful.

    Hint

    Adrenaline before action.

    Answer

    Excitement makes the adrenal glands release adrenaline into the blood. It speeds the heartbeat and breathing, raises blood sugar and sends more blood to muscles even before she moves. This prepares her muscles to release energy quickly once the race starts.

13. Q13 · 3 marks · Short answerHOTS / competency

    A doctor finds high blood sugar in one patient and a swollen neck in another, both from the same hilly village with a sugary diet. Suggest the gland involved in each, the hormone, and one lifestyle advice for each.

    Hint

    Pancreas; thyroid.

    Answer

    High sugar: pancreas, too little insulin (diabetes); advise less sugar, regular exercise and medical treatment. Swollen neck: thyroid, too little thyroxine due to lack of iodine (goitre); advise using iodised salt.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.Define a hormone.Show answer

   A chemical messenger secreted by an endocrine gland into the blood, acting on a target organ.

2. 2.Give an example of an exocrine gland.Show answer

   Salivary gland (or sweat, tear gland).

3. 3.Location of the thyroid?Show answer

   In the neck, in front of the windpipe.

4. 4.Hormone of the adrenal gland?Show answer

   Adrenaline.

5. 5.Which hormone lowers blood sugar?Show answer

   Insulin.

6. 6.Where is the pituitary?Show answer

   At the base of the brain.

7. 7.Age range of adolescence?Show answer

   Roughly 11 to 19 years.

8. 8.Name two ways to tackle stress.Show answer

   Yoga and meditation (also time management, sports, hobbies).

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you give three differences between exocrine and endocrine glands?
• ☐Can you fill the four-gland table from memory?
• ☐Can you explain why the pancreas is a mixed gland?
• ☐Can you list physical changes in boys and girls?
• ☐Can you name four emotional changes?
• ☐Can you suggest four ways to manage stress?

Endocrine System and Adolescence: frequently asked questions