Concise Biology Class 10 ICSE Solutions for Chapter 12 - The Endocrine System

1. Fill in the blanks by selecting the appropriate alternative from those given in brackets-:

i) Regulation of activities inside the body are brought about by _______ & ______ systems. (Nervous/Digestive/Endocrine)

Ans: Regulation of activities inside the body are brought about by nervous & endocrine systems.

ii) Hormones are directly secreted into the _______ . (Organs/Lymph/Blood).

Ans: Hormones are directly secreted into the blood.

iii) Chemically some hormones are _______ , some steroids , some ______.(Proteins/Amines/Carbohydrates)

Ans:  Chemically some hormones are amines, some steroids, some proteins.

iv) Both _________ or deficiency of hormones lead to serious consequences.(excess/absence)

Ans: Both excess or deficiency of hormones lead to serious consequences.

v) Hormones produced in one species usually show ________ influence in other species.(similar/different)

Ans: Hormones produced in one species usually show similar influence in other species.

2. Give the characteristics of hormones pertaining to

i) Site of action

Ans: The site of action of hormones in most of the cases is far away from their source of secretion that is why here comes the role of blood that carry them to their target cells.

ii) Chemical nature

Ans: Biochemically hormones can be of different types such as-:protein as hormones-insulin, steroid as hormone- testosterone, etc.

iii) Manner of transportation

Ans: Being ductless in nature the secretions from the endocrine glands(hormones) directly pour into the blood where they carry towards their target cells.

Progress check page no. 156:-

1. Mention the three types of cells of islets of the Langerhans & name the hormones they secrete.

Ans: Three types of cells of islets of the Langerhans are-:

2. Mention the two principal ways in which insulin acts.

Ans: Principal ways in which insulin acts are-:

1. It promotes the utilization of sugar by the body cells.

2. Excess sugar is converted into glycogen & then stored in the liver & the muscles.

3. Name the following conditions:

i) Passage of much glucose in urine

Ans: The condition named as diabetes mellitus

Explanation: Due to the deficiency of insulin hormone excess of glucose became unable to get converted into glycogen hence, excess sugar is excreted in urine..

ii) Overdose of insulin makes the dibetic patient unconscious

Ans: The condition is named as insulin shock.

Excess secretion of insulin leads to lower levels of blood sugar that can cause unconsciousness in dibetic patients.

4. List any three symptoms of diabetes mellitus.

Ans: The symptoms of diabetes mellitus are-:

1. Weight loss.

2. Excess of hunger.

3. Excess of thrust.

4. Dry skin.

5. Name the two categories of hormones that are secreted by the adrenal cortex.

Ans: Hormones that are secreted by the adrenal cortex are-:

1. Mineralocorticoids-aldosterone.

2. Glucocorticoids- cortisol.

6. List any two effects of adrenaline.

Ans: Adrenaline is also known as the “fight-or-flight hormone”.The effects of it are-:

1. Increases heart rate.

2. Increases breathing rate.

3. Enlarged pupil size in the eyes.

Progress check page no.168:-

Fill in the blanks with correct alternatives-:

1. Thyroid is located close to ________. (Larynx , Kidney)

Ans: Thyroid is located close to the larynx.

2. Cretinism is caused due to ________ of thyroxine. (Under secretion/Oversecretion)

Ans: Cretinism is caused due to under secretion of thyroxine. 

3. Oversecretion of thyroxine causes ______  goitre. (Simple/Exophthalmic).

Ans: Oversecretion of thyroxine causes exophthalmic goitre.

4. The condition showing swelling in face & hands & slunginess due to hypothyroidism is called ________. (Cretinism/Myxoedema)

Ans: The condition showing swelling in the face & hands & slunginess due to hypothyroidism is called Myxoedema.

5. The hormone concerned with facing danger is _________. (Thyroxine/Cortisone/Adrenaline)

Ans: The hormone concerned with facing danger is adrenaline. 

6. Cortex & Medulla are the two regions of _________. (Thyroid/Adrenal)

Ans: Cortex & Medulla are the two regions of the adrenal.

7. One of the effects of increased secretion of adrenaline is _______. (Dry mouth/ Slowing of heartbeat/Arterioles of the digestive system dilate)  

Ans: One of the effects of increased secretion of adrenaline is dry mouth.

Progress check page no.159:-

1. Mention the following statements are true (T) or false (F). If false, rewrite the correct words (not words) striking out the single wrong one.

i) Pituitary is the size of lemon.

Ans: This statement is false.

Pituitary is the size of a pea.

ii) Pituitary has three lobes anterior , posterior & intermediate.

Ans: This statement is false.

Pituitary has two lobes anterior & posterior. Intermediate lobe is found in lower animals.

iii) Oversecretion of growth hormone in adults causes gigantism.

Ans: This statement is false.

Oversecretion of growth hormone in adults causes acromegaly.

iv) Vasopressin secreted by the anterior lobe controls the reabsorption of water from kidney tubules  

Ans: This statement is false.

Vasopressin secreted by the posterior lobe controls the reabsorption of water from kidney tubules 

2. Write the full form of -: 

i) TSH

Ans: i) TSH stands for thyroid-stimulating hormone

ii) LH 

Ans: ii) LH stands for luteinizing hormone

iii) ACTH

Ans: iii) ACTH stand for adrenocorticotropic hormone

iv) ADH 

Ans:  iv) ADH stands for antidiuretic hormone

3. What causes the following?

i) Acromegaly

Ans: Acromegaly is due to over secretion of growth hormone in adults. The person with this has certain characteristic features such as extra growth of bones of jaws, hands, and feet.

ii) Diabetes insipidus

Ans: Diabetes insipidus is caused by the hyposecretion of antidiuretic hormone. The person with this disorder urinates more frequently.

A. Multiple Choice Type

(Select the most appropriate option in each case)
1. A gland having endocrine as well as exocrine function is

(a) Pituitary

(b) Thyroid

(c) Pancreas

(d) adrenal

Ans: (c) pancreas

2. Exophthalmic goiter is caused due by the overactivity of

(a) thymus

(b) thyroid

(c) parathyroid

(d) adrenal cortex

Ans: (b) thyroid

3. The deficiency of ADH causes:

(a) diabetes mellitus

(b) diabetes insipidus

(c) dwarfism

(d) acromegaly

Ans: (b) diabetes insipidus

B. Very Short Answer Type

1. Name the following:

(a) The hormone produced by adrenal medulla.

Ans: Adrenaline

(b) The condition caused by the over secretion of insulin.

Ans: Hypoglycemia

(c) The hormone secreted by beta cells of the islets of Langerhans.

Ans: Insulin

(d) The interconnection between the two lobes of the thyroid gland (technical term).

Ans: Isthmus

(e) The hormone whose under secretion causes more urine formation.

Ans: Antidiuretic hormone (Vasopressin)

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

Ans: Adrenaline

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

Ans: If a child's thyroid gland is hypersecreting, he or she will be diagnosed with cretinism. Dwarfism, mental impairment, and other indications of cretinism might be seen.

3. Choose the odd one out from each series:

(a) The glands - thyroid, adrenal, pituitary, prostate

Ans: Prostate

(b) The conditions - cretinism, myxoedema, goiter, scurvy

Ans: Scurvy

(c) The hormones- insulin, glucagon, cretinism, thyroxine

Ans: Cretinism

(d) The hormonal sources - adrenal cortex, adrenal medulla, cortisone, pituitary

Ans: Cortisone 

4. Match the items of column I with those of column II.

Ans: 

5. Match the conditions in column A with the cause in column B.

Ans:

6. Identify the odd one in each of the following and mention what the rest are:

(a) Larynx; glucagon; testosterone; prolactin

Ans: Larynx

Larynx is the soundbox whereas the other three i.e. testosterone; glucagon; and prolactin are hormones.

(b) Adrenaline; penicillin; insulin; thyroxin

Ans: Penicillin

Penicillin is an antibiotic whereas insulin; adrenaline; thyroxine are hormones.

(c) Stomach; ileum; liver; adrenaline

Ans: Adrenaline

Adrenaline is a hormone whereas the ileum; stomach, and liver are the organs of the digestive system.

(d) TSH; GH; ADH; insulin

Ans: Insulin

Insulin is secreted by the pancreas whereas TSH, GH, ADH are the hormones which are secreted by the pituitary gland.

(e) Iodine; cretinism; goiter; myxoedema

Ans: Iodine

Iodine is necessary for the production of thyroxine hormone. Whereas goitre, cretinism, myxoedema are the deficiencies that occur because of the deficiency of thyroxine.

7. Given below are a group of terms. In each group, the first pair indicates the relationship between the two terms. Suggest the suitable word(s) for the fourth place.

(a) Beta cells: Insulin:: Alpha cells: ………………….

Ans: Glucagon

(b) Children: Cretinism:: Adults: ………………….

Ans: Myxoedema

(c) Undersecretion: Dwarfism:: Oversecretion: ………………….

Ans: Gigantism

(d) Diabetes mellitus : Insulin :: Diabetes insipidus : ………………….

Ans: Antidiuretic hormone (ADH)

C. Short AnswerType

1. Mention the name of diseases based on the clues/ symptoms given below:

(a) Urine is loaded with sugar.

Ans: Hyperglycemia

(b) Swelling in the neck.

Ans: Simple goitre

(c) Dwarfism and mental retardation in children.

Ans: Cretinism

(d) Eyes are protruded.

Ans: Exophthalmic goitre

(e) Excessive growth of bones in the face, hands and feet.

Ans: Acromegaly in adults and gigantism in children

2. Write the exact location of each of the following glands:

(a) Thyroid

Ans: It is located directly below the larynx in the front section of the neck. 

(b) Adrenal

Ans: On the top of each kidney, it appears like a cap.

(c) Pancreas

Ans: The pancreas is positioned in the upper left abdomen behind the stomach. 

(d) Pituitary

Ans: It is located below the hypothalamus at the base of the midbrain. 

3. Name the following:

(a) Three hormones secreted from islets of Langerhans of the pancreas.

Ans: Three hormones secreted from islets of Langerhans of the pancreas are:-

1. Insulin

2. Somatostatin

3. Glucagon

(b) Two types of cortical hormones.

Ans: Two types of cortical hormones are:-

1. Glucocorticoids

2. Mineralocorticoids

(c) Six hormones secreted from anterior pituitary.

Ans: Six hormones secreted from anterior pituitary

1. Growth hormone (somatostatin)

2. Adreno-corticotropic hormone (ACTH)

3. Prolactin

4. Follicle-stimulating hormone (FSH)

5. Thyroid-stimulating hormone (TSH)

6. Luteinizing hormone (LH)

(d) Two hormones secreted from the posterior pituitary.

Ans: Two hormones secreted from the posterior pituitary are:

1. Vasopressin

2. Oxytocin

(e) The emergency hormone.

Ans: Adrenaline 

4. Write the main function of each of the following hormones.

Ans:

5. Name the hormones responsible for the given functions.

Ans: 

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

Ans: Adrenaline is a hormone that helps the body for any type of emergency. The hormone adrenaline causes the heart to beat quicker. Simultaneously, it causes the arterioles of the digestive system to contract, limiting the blood supply to the digestive system and making the mouth dry.

7. 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.

Ans: 

8. Complete the following table by filling in the blanks numbered 1 to 7.

Ans: 

9. Complete the following table by filling in the blank spaces numbered 1 to 8.

Ans: 

D. Descriptive Type

1. Define the following terms:

(a) Endocrine system

Ans: The endocrine system is made up of multiple endocrine glands/glandular cells that work together to bring about chemical coordination in the body.

(b) Hormones

Ans: Hormones are secretions produced by certain cells or glands in the body that are conveyed throughout the body by the bloodstream but only affect one or more specific body regions (target organ or cells).

(c) Myxoedema

Ans: Myxoedema is a disorder that affects individuals with hypothyroidism and causes sluggishness and swelling of the face and hands.

2. Distinguish between the following pairs:

(a) Exocrine and endocrine glands (manner of secretion)

Ans:

(b) Enzymes and hormones (chemical composition and mode of action)

Ans: 

(c) Nervous control and hormonal control (transmission and effect)

Ans: 

(d) Diabetes mellitus and diabetes insipidus (cause and symptoms)

Ans: 

(e) Addison's disease and Cushing's syndrome (cause and sugar level)

Ans: 

3. Give reason:

(a) Adrenaline is often described as the emergency hormone.

Ans: Adrenaline is known as the "emergency hormone" since it prepares the body to deal with any emergency circumstance, whether it's a fight or a flight response. More adrenaline is released, which causes the heart to beat faster, breathing to become faster, and the production of more glucose into the bloodstream to meet the energy need.

(b) Pituitary is popularly called the master gland.

Ans: Pituitary is popularly called as the master gland because it regulates the functions of all other endocrine glands.

(c) People living in the low Himalayan hilly regions often suffer from goitre.

Ans: Iodine deficiency in the soil, and thus in the food grown there, causes goitre in people who live in the low Himalayan hills regions. Goitre is caused by a lack of thyroxine, which is caused by a lack of iodine.

(d) Simple goitre can be prevented by using iodised salt in food.

Ans: Iodine, an active ingredient in the formation of thyroxine, is found in iodised salt. To avoid simple goitre, it is suggested that one should use iodized salt in your food.

4. Do you agree with the statement- "All hormones are chemical signals"? yes/no. Justify your answer.

Ans: Hormones are amines, peptides, or steroids in their chemical form. They play a role in controlling the body's metabolism. They have the ability to cause certain chemical changes in the body during the metabolic process. Hormones are referred to as 'chemical messengers.'

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.

Ans: The cells of the pancreas that produce:

1. Glucagon: Alpha cells of the islets of Langerhans

2. Insulin: Beta cells of the islets of Langerhans

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

Ans: The main function of:

1. Glucagon- It stimulates the breakdown of glycogen into glucose in the liver, which boosts blood glucose levels.

2. Insulin- It is a hormone that keeps blood glucose (sugar) levels stable.

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

Ans: A gland that does not pour its secretions into a channel is called an endocrine gland, whereas a gland that does pour its secretions into a duct is called an exocrine gland. The pancreas is classified as an endocrine gland since it generates hormones like glucagon, insulin, and somatostatin straight into the blood rather than through a duct. It is an exocrine gland since it secretes pancreatic secretions for digestion through a duct. As a result, the pancreas is classified as an exo-endocrine gland.

d. Why is insulin not given orally but is injected into the body?

Ans: Insulin cannot be taken orally because digestive juices destroy insulin, rendering it useless in the body.

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

Ans: Islets of Langerhans

f. Where in the body is the pancreas located?

Ans: The pancreas is placed behind the stomach in the abdomen.

2. Given below 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?

Ans: This portion is located in the neck region above the sternum.

(b) Name the structures numbered 1-3.

Ans: 1- Larynx, 2 - Thyroid gland, 3 - Trachea

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

Ans: One main function of:

Larynx- The larynx is the voice box that houses the vocal chords. It aids in the production of sound.

Thyroid Gland- Thyroxine and calcitonin, two important hormones, are produced by the thyroid gland.

Trachea- The windpipe, or trachea, aids in the passage of air to and from the respiratory system during breathing.

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

Ans: The thyroid gland is the second structure. Because it is an endocrine gland, it is ductless and secretes directly into the bloodstream. As a result, there is no duct.

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

(a) Name the parts numbered 1 to 4.

Ans:  1- Pituitary gland, 2 - thyroid gland, 3 - pancreas, 4 - adrenal glands

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

Ans: The glands depicted in the diagram above are all endocrine glands. They produce vital hormones and secrete them directly into the bloodstream.

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

Ans: Iodine is essential for the normal working of thyroid gland.

4. Given below are two diagrams (one is correct, the other one is somewhat 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?

Ans: A has the error.

(b) What is the error?

Ans: The hormones released by the endocrine gland are represented in image A to be travelling in just one direction, that is, towards the target organ. However, hormones injected into the bloodstream may have one or multiple target sites at any given time. The blood carries the arrows to all regions of the body, but their influence is only felt in one or more of them.

F. Think and Connect

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

Ans: 

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

Ans:

Conclusion

The main objective of these solutions is to provide the student with solutions that have been prepared by subject experts after proper analyzing and understanding the subject and the previous year papers.