Endocrine Glands

August 11, 2025

The endocrine system is a vital network of glands that release hormones directly into the bloodstream. Unlike the exocrine system, which uses ducts to transport secretions, endocrine glands send chemical messengers—hormones—throughout the body to regulate functions like growth, metabolism, and reproduction, ensuring internal balance (homeostasis).

Major Endocrine Glands and Their Roles

Pituitary Gland – Often called the “master gland,” it sits at the brain’s base and controls other endocrine glands.

Thyroid Gland – Located in the neck, it produces thyroxine, which manages metabolism. Too much (hyperthyroidism) or too little (hypothyroidism) can cause health issues, including goiter.

Adrenal Glands – These sit atop the kidneys and produce adrenaline (epinephrine), the “fight or flight” hormone. It boosts heart rate, blood pressure, and energy during stress.

Pancreas – This organ has dual roles. Its endocrine part (Islets of Langerhans) releases insulin (lowers blood sugar) and glucagon (raises blood sugar). Insulin deficiency leads to diabetes.

Gonads – The reproductive glands: testes (males) produce testosterone for male traits, while ovaries (females) release estrogen and progesterone, regulating the menstrual cycle and female characteristics.

Hormone Regulation: The Feedback System

Hormone levels are tightly controlled by feedback loops. If levels rise too high, the gland slows production; if they drop too low, secretion increases. This balance prevents disorders and keeps bodily functions running smoothly.

By adjusting hormone release as needed, the endocrine system ensures stability and health.

A. MULTIPLE CHOICE TYPE:

1) A gland having endocrine as well as exocrine function is

(a) pituitary

(b) thyroid

(d) adrenal

Ans: (c) pancreas

2) Exophthalmic goitre is caused due to the over activity of

(a) thymus

(b) thyroid

(d) adrenal cortex.

Ans: (b) thyroid

3) The secretion of ADH (anti-diuretic hormone) is inhibited by

(a) emotion and stress

(b) nicotine

(d) morphine

Ans: (c) alcohol

B. VERY SHORT ANSWER TYPE:

1) Name the following:

(a) The three hormones produced by pancreas

(b) The hormone produced by adrenal medulla

(c) The condition caused by the over secretion of insulin

(d) The hormone secreted by β (beta) cells of the islets of Langerhans

(e) The hormone which increases blood pressure

(f) The hormone causing more urine formation

(g) The hormone which stimulates the entire sympathetic nervous system.

Ans: (a) Insulin, glucagon, somatostatin

(b) Adrenaline

(d) Insulin

(e) Adrenaline

(f) Anti-diuretic hormone (Vasopressin)

(g) Adrenaline

2) What would a child suffer from, if there was hyposecretion from his thyroid?

Ans: A child with hyposecretion (or an underactive thyroid) from their thyroid gland would suffer from a condition called cretinism.This condition is marked by severely stunted physical growth and mental development.

The thyroid gland produces thyroxine, a hormone crucial for regulating the body’s metabolic rate and for the proper growth and maturation of the body and brain, particularly during a child’s developmental years. Without sufficient thyroxine, a child’s development is severely impaired, leading to:

Dwarfism or stunted growth.
Mental and intellectual disabilities.
Delayed bone formation and puberty.
Other physical symptoms like a thick tongue and dry, coarse skin.

Early detection and treatment with thyroid hormone replacement therapy can prevent these long-term effects.

3 )Choose the odd one out from each series

(a) The glands – thyroid, adrenal, pituitary, prostate …………………………………………

(b) The conditions – cretinism, myxoedema, goiter, scurvy ………………………………………….

(c) The hormones – insulin, glucagon, cretinism, thyroxine ………………………………………….

(d) The hormonal sources – adrenal cortex, adrenal medulla, cortisone, pituitary. ……………………………………………..

Ans: (a) Prostate

(b) Scurvy

(d) Cortisone

4) Identify the odd one in each of the following and mention what the rest are:

(a) Larynx; glucagon; testosterone; prolactin……………………………………..

(b) Adrenaline; penicillin; insulin; thyroxin…………………………………

(c) Stomach ; ileum; liver; adrenaline…………………………………..

(d) TSH; GH; ADH; Insulin…………………………………….

(e) Iodine, cretinism, goiter, myxedema………………………………….

Ans:

a) Larynx: Larynx is the odd one out. Glucagon, testosterone, and prolactin are all hormones. The larynx, on the other hand, is the voice box, a part of the respiratory system.

(b) Penicillin : Penicillin is the odd one out. Adrenaline, insulin, and thyroxin are all hormones produced by the body. Penicillin is an antibiotic drug, not a naturally occurring hormone.

(d) Insulin: Insulin is the odd one out. TSH (Thyroid-stimulating hormone), GH (Growth hormone), and ADH (Antidiuretic hormone) are all hormones produced by the pituitary gland. Insulin is produced by the pancreas.

(e) Iodine: Iodine is the odd one out. Cretinism, goiter, and myxedema are all conditions related to thyroid gland dysfunction. Iodine is a mineral that is essential for the production of thyroid hormones, but it is not a condition itself.

5) Match the items of column I with those of column II

column I	column II
1. (beta) cells of islets of Langerhans	(a) condition due to undersecretion of thyroxine in adults
2. Thyroid	(b) Glucocorticoids
3. Cretinism	(c) Exophthalmic goitre
4. Addison’s disease	(d) Increases heart beat
5. Hypothyroidism	(e) Thyroxine
6. Myxoedema	(f) Adrenal cortex
7. Adrenaline	(g) Insulin
8. Cortisone	(h) Under secretion of thyroxine in a child

Ans:

column I	column II
1. (beta) cells of islets of Langerhans	(g) Insulin
2. Thyroid	(c) Exophthalmic goitre
3. Cretinism	(h) Under secretion of thyroxine in a child
4. Addison’s disease	(b) Glucocorticoids
5. Hypothyroidism	(e) Thyroxine
6. Myxoedema	(a) condition due to undersecretion of thyroxine in adults
7. Adrenaline	(d) Increases heart beat
8. Cortisone	(f) Adrenal cortex

6) match the conditions in column A with the cause in column B.

column A	column B.
(a) Dwarfism and mental retardation	i. shortage of glucose in blood
(b) Diabetes mellitus	ii. Over secretion of growth hormone
(c) Excess of glucose in blood	iii. Insulin shock
(d) Gigantism	iv. Over secretion of thyroxine
(e) Enlargement of breasts in adult males	v. Hypothyroidism
(f) Exophthalmic goitre	vi. Over secretion of cortical hormones

Ans:

column A	column B.
(a) Dwarfism and mental retardation	v. Hypothyroidism
(b) Diabetes mellitus	i. shortage of glucose in blood
(c) Excess of glucose in blood	iii. Insulin shock
(d) Gigantism	ii. Over secretion of growth hormone
(e) Enlargement of breasts in adult males	vi. Over secretion of cortical hormones
(f) Exophthalmic goitre	iv. Over secretion of thyroxine

C. SHORT ANSWER TYPE:

1) Mention which of the statements are true (T) and which are false (F). Give reason in support of your answer.

(a) Adrenaline is often described as emergency hormone

(b) There are two kinds of diabetes (mild and severe) related to two different hormones.

(c) Simple goiter can be prevented by using iodised salt in food.

(d) Pituitary is popularly called the master gland

(e) Hormones ‘obey’ the commands like ‘enough, slow down or ‘two little, speed up’. (f) Gigantism and dwarfism in humans basically depend on the quality and quantity of the food eaten during early growing age.

Ans: (a) Adrenaline is often described as an emergency hormone.

True. Adrenaline is released during stressful situations, preparing the body for a “fight or flight” response by increasing heart rate, blood pressure, and blood glucose.

(b) There are two kinds of diabetes (mild and severe) related to two different hormones.

False. The two main types of diabetes, Type 1 and Type 2, are both related to the hormone insulin. Type 1 involves a lack of insulin production, while Type 2 involves the body’s improper use of insulin.

True. Simple goiter is often caused by an iodine deficiency. Since iodine is crucial for producing thyroid hormones, using iodized salt ensures an adequate supply, thus preventing the condition.

(d) Pituitary is popularly called the master gland.

True. The pituitary gland is often called the “master gland” because it produces hormones that influence several other important glands in the body. These include the thyroid, adrenal glands, and reproductive organs (testes and ovaries). By controlling these glands, the pituitary gland helps regulate essential functions such as growth, metabolism, and reproduction. Its ability to maintain balance in the body makes it a key player in overall health.

Because it coordinates so many critical processes, the pituitary gland ensures that different systems work together smoothly. If it doesn’t function properly, it can lead to various hormonal imbalances, affecting everything from energy levels to fertility. This small but powerful gland plays a central role in keeping the body’s functions in check.

(e) Hormones ‘obey’ the commands like ‘enough, slow down’ or ‘too little, speed up’.

True. This describes the negative feedback mechanism, which regulates hormone levels. High levels of a hormone signal the producing gland to slow down, and low levels signal it to speed up production, maintaining balance.

(f) Gigantism and dwarfism in humans basically depend on the quality and quantity of the food eaten during early growing age.

False. Gigantism and dwarfism are primarily caused by the overproduction or underproduction of Growth Hormone (GH) from the pituitary gland. They are hormonal disorders, not direct results of diet.

2) How do endocrine glands differ from other glands?

Ans: Endocrine glands differ from other glands primarily in how they release their secretions. Endocrine glands are ductless, meaning they secrete hormones directly into the bloodstream. These hormones then travel to their target organs throughout the body.They release their secretions—such as sweat, saliva, tears, or digestive enzymes—through these ducts onto an epithelial surface, either inside or outside the body.A gland like the pancreas is considered a mixed gland because it has both endocrine and exocrine functions. It secretes hormones like insulin and glucagon directly into the bloodstream (endocrine function) and also releases digestive enzymes into the small intestine through a duct (exocrine function).

3) Mention any two differences between a hormone and an enzyme.

Ans: Hormones and enzymes are both crucial biological molecules, but they function differently.Hormones are chemical messengers made by endocrine glands and released into the bloodstream. They travel to specific target organs to regulate bodily functions like growth and metabolism. Hormones are generally used up or broken down after their work is done.Enzymes, on the other hand, are biological catalysts secreted by exocrine glands. Their job is to speed up biochemical reactions without being consumed in the process. This means a single enzyme molecule can be reused multiple times to perform the same function.

4) Do you agree with the statement – “ All hormones are chemical signals”? Yes / No . Justify your answer.

Ans: Hormones are chemical messengers secreted by endocrine glands that travel through the bloodstream. They function by binding to specific receptors on target cells to initiate a biological response, which in turn regulates various bodily functions. This mechanism ensures that hormones act on the correct cells to maintain overall physiological balance.

5) Why is iodine, as a nutrient, important to our body?

Ans: Iodine is a vital mineral that your body needs to produce thyroid hormones, such as thyroxine. These hormones are essential for regulating metabolism, which impacts your energy levels, heart rate, and body temperature.

A deficiency in iodine can lead to hypothyroidism, a condition characterized by low thyroid hormone production. Symptoms include fatigue, weight gain, and an enlarged thyroid gland called a goiter. A severe lack of it during these times can cause permanent damage, including intellectual disability.

6) If you stand to make your maiden speech before a large audience your mouth dries up and your heart rate increases. What brings about these changes?

Ans: When you are about to give a maiden speech, the stress of the situation triggers a “fight-or-flight” response in your body. This is primarily controlled by the adrenal glands, which release the hormone adrenaline (epinephrine) into the bloodstream.

This surge of adrenaline causes several physiological changes to prepare your body for a perceived threat:

Increased Heart Rate: Adrenaline signals the heart to beat faster, pumping more oxygenated blood to your muscles and brain.
Dry Mouth: The hormone redirects blood flow away from non-essential functions like digestion and saliva production, causing your mouth to feel dry.

These changes are a natural response to stress, designed to give you a boost of energy and focus.

7) If one adrenal gland is removed, the other one gets enlarged to some extent. How do you explain this change?

Ans: When one adrenal gland is removed, the remaining one becomes larger through a process called compensatory hypertrophy. This happens because the body needs to keep its hormone levels, especially cortisol, stable.

Here’s how it works:

The removal of one gland causes a drop in hormone levels.
The brain’s hypothalamus and pituitary gland detect this change and release more adrenocorticotropic hormone (ACTH).
The extra ACTH stimulates the remaining adrenal gland to increase in both cell size and number, making it larger. This allows the gland to produce more hormones and restore the body’s balance.

8) Name the two kinds of diabetes? Mention their symptoms and the causes.

Ans:

Feature	Type 1 Diabetes	Type 2 Diabetes
Cause	An autoimmune disease where the body’s immune system destroys insulin-producing cells in the pancreas. This results in little to no insulin being produced.	The body either doesn’t make enough insulin or can’t use it properly (insulin resistance).
Symptoms	Frequent urination, increased thirst, unexplained weight loss, blurred vision, and extreme hunger.	Increased thirst, frequent urination, fatigue, blurred vision, and sores that heal slowly.
Triggers	A combination of genetic and environmental factors	A combination of lifestyle factors (sedentary lifestyle, poor diet, obesity) and genetics.

9) People living in the low Himalayan hilly regions often suffer from goiter. What could be the possible reason for it?

Ans: People in low Himalayan hilly regions often suffer from goiter because their diet is deficient in iodine.

Here’s why:

Iodine-Poor Soil: Mountainous areas are often far from the sea, and the soil in these regions has very low levels of iodine. This means that the crops and vegetables grown there also lack this essential mineral.
Hormone Production: The thyroid gland requires iodine to produce the hormone thyroxine, which regulates metabolism.
Compensatory Enlargement: When there isn’t enough iodine, the thyroid gland struggles to produce thyroxine. In an attempt to compensate, it enlarges, leading to the characteristic swelling in the neck known as goiter

10) Given below is a table designed to give the names of the glands, the hormones produced, their chief functions, the effects of over secretion and under secretion in respect of thyroid, pituitary and pancreas. Fill up the blanks 1-13

Sl. No.	Source Gland cells	Hormone produced	Chief function	Effect of over secretion	Effect of under secretion
1.	_________	thyroxine	_________	_________	_________
2.	Beta cells of Islets of Langerhans	_________	Promotes glucose utilization by the body cells	_________	_________
3.	_________	Growth hormone	_________	_________	Dwarfism
4.	_________	Vasopressin	Increases reabsorption of water from kidney tubule	_________	_________

Ans:

Sl. No.	Source Gland cells	Hormone produced	Chief function	Effect of over secretion	Effect of under secretion
1.	Thyroid	thyroxine	Regulates basal metabolism	Exophthalmic goiter	Simple goiter, cretinism in children and myxoedema in adults
2.	Beta cells of Islets of Langerhans	Insulin	Promotes glucose utilization by the body cells	Hypoglycemia	Diabetes mellitus
3.	Anterior pituitary	Growth hormone	Promotes growth of the whole body	Gigantism	Dwarfism
4.	Posterior pituitary	Vasopressin	Increases reabsorption of water from kidney tubule	More concentrated and less amount of urine	Diabetes insipidus

11) Complete the following table by filling in the blanks numbers 1 to 7?

Gland	Hormone secreted	Effect on body
_________	_________	Regulates basal metabolism
Pancreas (“beta” cells)	_________	Controls blood sugar level
_________	_________	Increases heart beat
_________	Thyroid stimulating hormone	_________

Ans:

Gland	Hormone secreted	Effect on body
Thyroid	Thyroxine	Regulates basal metabolism
Pancreas (“beta” cells)	Insulin	Controls blood sugar level
Adrenal gland	Adrenaline	Increases heart beat
Anterior pituitary	Thyroid stimulating hormone	Stimulates thyroxine secretion

12) Complete the following table by filling in the blank spaces numbered 1 to 8:

Gland	Secretions	Effect on body
_________	oestrogen	_________
Alpha cells of islets of Langerhans	_________	_________
_________	_________	Protruding eyes
_________	_________	Gigantism

Ans:

Gland	Secretions	Effect on body
Ovary	oestrogen	development of secondary sexual characteristics
Alpha cells of islets of Langerhans	Glucagon	Raises blood sugar level
Thyroid	Hypersecretion of thyroxine	Protruding eyes
Anterior pituitary	Hypersecretion of Growth hormone	Gigantism

D. LONG ANSWER TYPE:

1) Compare the hormonal response with the nervous response with respect to their speed, transmission and the general nature of changes brought about.

Ans:

Hormonal Response	Nervous Response
Hormonal response is slow	Nervous response is immediate.
Hormones are chemical messengers transmitted through blood stream.	Nerve impulses are transmitted in the form of electro-chemical responses through nerve fibres.
This response brings about a specific chemical changes.Therefore it regulates the metabolism	This response does not bring any chemical change during metabolism

2) Mention three important differences between the action of hormones and that of nerves in the regulatory mechanism of our body.

Ans:

Action of Hormones	Action of Nerves
The effect of hormones is wide spread in the body. They can show their effect on more than one target site at a time.	The nerve response affects only particular glands.
The effect of hormones can be short-lived or long lasting	The effect of nervous response is always short-lived.
Cannot be modified by the previous learning experiences.	Can be modified by the previous learning experiences.

E. STRUCTURED / APPLICATION/ SKILL TYPE:

1) Study the diagram given below and then answer the questions that follow:

(a) Name the cells of the pancreas that produce (1) glucagon (2) Insulin

(b) state the main function of (1) glucagon and (2) insulin

(c) Why is the pancreas referred to as an exo-endocrine gland?

(d) why is insulin not given orally but in injected into the body:

(e) What is the technical term for the cells of the pancreas that produce endocrine hormones?

(f) where in the body is the pancreas located?

Ans: (a) Cells of the Pancreas

Glucagon is produced by the alpha (α) cells of the pancreas.
Insulin is produced by the beta (β) cells of the pancreas.

(b) Main Functions

Glucagon’s main function is to increase blood sugar levels when they get too low.
Insulin’s main function is to decrease blood sugar levels when they get too high. It helps body cells absorb glucose from the blood and promotes the storage of excess glucose as glycogen in the liver and muscles.

The pancreas is a mixed gland because it has both exocrine and endocrine functions. * Its exocrine function involves producing digestive enzymes that are secreted into the small intestine through ducts.

Its endocrine function involves producing hormones like insulin and glucagon, which are secreted directly into the bloodstream without ducts.

(d) Insulin Administration

When ingested, the stomach’s strong acids and digestive enzymes would break it down, making it ineffective.

(e) Endocrine Cells of the Pancreas

The clusters of cells in the pancreas that produce these hormones are called the Islets of Langerhans. These islets contain the alpha and beta cells.

(f) Location of the Pancreas

The pancreas is located in the upper abdomen, behind the stomach, and nestled within the curve of the duodenum (the first part of the small intestine).

2) Given alongside is a portion from the human body showing some important structure in the ventral (front) view.

(a) Where is this portion located in the body?

(b) Name the structure numbered 1 – 3

(c) state one main function of each of the structures named above.

(d) Is there any duct to carry the secretions from the structure numbered 2? If so, give its name.

Ans: a) Location

The structures shown are located in the neck, superior to the sternum (breastbone).

(b) Identification

Larynx
Thyroid gland
Trachea

(c) FunctionsThe thyroid gland secretes thyroxine to control metabolism and calcitonin to balance calcium levels. The trachea (windpipe) transports air from the larynx to the lungs. These neck structures play vital roles in breathing and hormone regulation.

(d) Why Structure 2 Has No Duct

Structure 2 is the thyroid gland, which is an endocrine gland. Endocrine glands are ductless, meaning they secrete their hormones directly into the bloodstream rather than through ducts.

3) Given alongside is an outline diagram of the human body showing the position of certain organs.

(a) Name the parts numbered 1 to 4

(b) what is common to all these parts in regard to the nature of their functions?

(c) Name the nutrient element which is essential for the normal working of part 2.

Ans: a)

1)is in the neck region. It’s the location of the thyroid gland.

2)is in the chest cavity, specifically the center. This is the heart.

3) is in the abdominal cavity. This is the pancreas.

4) is in the lower abdomen, on the side. This is the adrenal gland.

(b) All these parts are endocrine glands. Their common function is to produce and secrete hormones directly into the bloodstream to regulate various bodily processes.

4) Given below are two diagrams (one is correct the other is some what incorrect) showing the transport of a hormone from its source gland/ cell to the target organ/ cell.

(a) which one has the error A or B? ……………

(b) what is the error? …………………

Ans: a) Diagram A has the error.

(b) The error in Diagram A is that the hormone is shown traveling outside the bloodstream, directly to the target cell. In reality, endocrine hormones are always secreted directly into the bloodstream and are transported by the blood to reach their target cells, as correctly shown in Diagram B.

Endocrine Glands

Ans:

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