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Chapter 7

Endocrine System in Humans

Class 8 - Living Science Biology Ratna Sagar


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Question 1

Exocrine glands are ductless glands.

Answer

False

Correct statement — Endocrine glands are ductless glands.

Question 2

Hormones are secreted by endocrine glands directly into the nerves.

Answer

False

Correct statement — Hormones are secreted by endocrine glands directly into cell or in tissue spaces adjacent to them.

Question 3

Pituitary is the master gland.

Answer

True

Question 4

Insulin is released by the thyroid gland.

Answer

False

Correct statement — Insulin is released by the islets of Langerhans in the Pancreas.

Question 5

Thyroxine hormone regulates the speed of cellular metabolism.

Answer

True

Tick the most appropriate answer

Question 1

Endocrine glands release

  1. enzymes
  2. hormones
  3. digestive chemicals
  4. gas

Answer

hormones

Reason — Chemical substances secreted by endocrine glands in the blood directly is called hormone.

Question 2

Which of these is called the master gland?

  1. pituitary
  2. thyroid
  3. ovary
  4. adrenal

Answer

pituitary

Reason — Pituitary gland is called the master gland as it controls the functioning of all other endocrine glands.

Question 3

The hormone secreted by the pituitary gland that controls overall growth is

  1. growth hormone
  2. insulin
  3. adrenaline
  4. auxin

Answer

growth hormone

Reason — The pituitary gland secretes growth hormone that controls overall growth of the body

Question 4

The hormone thyroxine is released by the

  1. parathyroid gland
  2. pituitary gland
  3. thyroid gland
  4. ovary

Answer

thyroid gland

Reason — Thyroxine is released by the thyroid gland. It regulates the speed of cellular metabolism.

Question 5

Conversion of glucose into glycogen is controlled by

  1. thyroxine
  2. insulin
  3. adrenaline
  4. oestrogen

Answer

insulin

Reason — Insulin is the hormone secreted by islet of Langerhans. It regulates the amount of sugar in blood by Converting glucose into glycogen.

Question 6

Which of the following glands is both endocrine as well as exocrine?

  1. thyroid
  2. pituitary
  3. pancreas
  4. adrenal

Answer

pancreas

Reason — Pancreas acts as both endocrine as well as exocrine because its exocrine part — ducts of acini release pancreatic fluid (digestive juice) and endocrine part — islet of Langerhans secrete insulin hormone.

Question 7

Which of the following hormone regulates the amount of glucose in the blood?

  1. growth hormone
  2. insulin
  3. adrenaline
  4. auxin

Answer

insulin

Reason — Insulin converts extra glucose of blood into glycogen which is stored in liver.

Fill in the blanks

Question 1

The adrenal glands secrete ............... and noradrenaline hormones.

Answer

The adrenal glands secrete adrenaline and noradrenaline hormones.

Question 2

The endocrine component of pancreas consists of islets of ............... which secrete the insulin hormone.

Answer

The endocrine component of pancreas consists of islets of Langerhans which secrete the insulin hormone.

Question 3

............... helps the person cope with an emergency.

Answer

Adrenaline helps the person cope with an emergency.

Question 4

The ............... gland secretes growth hormone that regulates growth in the body.

Answer

The pituitary gland secretes growth hormone that regulates growth in the body.

Question 5

The ............... secrete the male sex hormone called testosterone.

Answer

The testes secrete the male sex hormone called testosterone.

Match the columns

Question 1

Sl.
No.
Column AColumn B
1.pancreasadrenaline
2.pituitary glandoestrogen
3.thyroid glandgrowth hormone
4.adrenal glandinsulin
5.testesthyroxine
6.ovarytestosterone

Answer

Sl.
No.
Column AColumn B
1.pancreasinsulin
2.pituitary glandgrowth hormone
3.thyroid glandthyroxine
4.adrenal glandadrenaline
5.testestestosterone
6.ovaryoestrogen

Write true or false. Correct the false statements.

Question 1

Pancreas is an exocrine gland.

Answer

False

Correct statement — Pancreas is endocrine as well as exocrine gland.

Question 2

Thyroid gland secretes adrenaline and noradrenaline to help a person cope with emergency situations

Answer

False

Correct statement — Adrenal gland secretes adrenaline and noradrenaline to help a person cope with emergency situations.

Question 3

Under-secretion of thyroxine leads to hypothyroidism.

Answer

True

Question 4

The period of transition from childhood to adulthood is known as adolescence.

Answer

True

Question 5

The mental tension or worry caused by problems is called stress.

Answer

True

Differentiate between

Question 1

Endocrine and exocrine glands

Answer

Sl.
No.
Endocrine glandsExocrine glands
1.Endocrine glands are specialized glands which release their secretions directly into cells or the surrounding tissue.Exocrine glands are glands which release their secretions through ducts to the target organ.
2.Endocrine glands are ductless glands.Exocrine glands are glands with ducts.
3.Endocrine glands secrete hormones.Exocrine glands secrete enzymes.
4.Response time is slower since the secretion has to be carried through blood.Response time is fast since the secretion is carried through ducts.
5.They control long term activities of the target organ.They control short term activity.
6.Examples are: Pituitary gland and thyroid glandExamples are: Salivary glands and sweat glands

Question 2

Thyroxine and insulin

Answer

Sl.
No.
ThyroxineInsulin
1.It is secreted by thyroid gland.It is secreted by islet of Langerhans.
2.It regulates the rate of cellular metabolism and body temperature.It regulates the amount of of glucose in the blood and conversion of glucose into glycogen.
3.Irregular secretion leads to hyperthyroidism or hypothyroidism.Irregular secretion leads to diabetes.

Answer the following in short

Question 1

What are endocrine glands?

Answer

The ductless glands that release their secretion (hormone) directly into cells or in tissue spaces adjacent to them are called endocrine glands.

Question 2

What are hormones?

Answer

Hormones are chemical messengers secreted by endocrine glands that help to control and coordinate various metabolic activities in the body.

Question 3

Write the function of the pituitary gland in our body.

Answer

The pituitary gland is also known as master gland. Its functions are:

  1. It controls the functioning of all other endocrine glands.
  2. It secretes growth hormones which control the overall development or growth of the body, muscles and bones.
  3. It increases rate of protein synthesis.

Question 4

What is the function of the islets of Langerhans?

Answer

The islets of Langerhans secrete insulin which regulates the amount of glucose in the blood and conversion of glucose into glycogen.

Question 5

Name the hormones secreted by the ovaries.

Answer

Female sex hormones called oestrogen and progesterone are secreted by the ovaries.

Answer the following in detail

Question 1

Describe the characteristic features of hormones.

Answer

Hormones are chemical messengers secreted by endocrine gland that help to control and coordinate various metabolic activities in the body. They are released directly into the bloodstream. The characteristics of hormones are as follows:

  1. Hormones are produced in small quantities.
  2. They act very fast, but slower than the nerve impulses.
  3. They act on cells or organs located away from their sources.
  4. They are destroyed soon after their action and thus not stored in the body.
  5. They coordinate long-term process, such as sexual development and growth.

Question 2

What happens when the thyroid gland secretes less thyroxine?

Answer

When thyroid gland secretes less thyroxine, it leads to a condition known as hypothyroidism. It can be cause due to deficiency of Iodine. Hypothyroidism makes a person sleepy and sluggish, leading to weight gain. It leads to the swelling of the thyroid gland, a condition called goitre.

Question 3

How is the level of glucose regulated by the pancreas?

Answer

The endocrine component of the Pancreas called the islets of Langerhans secretes insulin hormone. Insulin regulates amount of glucose in the blood. Extra glucose in the body is converted into glycogen by insulin and stored in the liver.

Question 4

State the various physical changes that occur during adolescence.

Answer

The various physical changes that occur during adolescence are:

  1. Sexual maturation — In males testes start producing testosterone and sperms. In females, the ovaries start releasing eggs and produce the female hormones, oestrogen and progesterone. Sex organs develop fully and secondary sexual characteristics like enlargement of external genital organs in males and enlargement of breasts in females also start.
  2. Increase in height — There is a spurt in growth hormone leading to sudden increase in height due to the elongation of the bones of the legs and arms. Age by which full height is attained is 14 to 15 years for girls and 18 to 19 years for boys.
  3. Change in body appearance — In males, the shoulders become broad and the chest becomes wide.The muscles also grow and develop more than in girls. In females, there is widening of the pelvic region and broadening of the hips. The breasts also develop and enlarge in size. Also in both males and females, hair starts growing in the armpit and pubic area. In males, facial hair (as beard and mustache) grows.
  4. Change in voice — There is growth in the voice box or larynx. It grows more in males than in females. As a result, males develop deep voice whereas females develop a high-pitched voice.

Question 5

State any two methods to counter and manage stress.

Answer

Two methods to counter and manage stress are:

  1. Meditation — In meditation, mind is allowed to rest by taking deep breaths and having positive thoughts without thinking much about the mistakes or weaknesses.
  2. Yoga — Regular yoga helps to overcome stress. So, we should devote some time to it every day.

Complete the table

Question 1

Given below is an incomplete table showing names of the endocrine gland, hormones secreted by them and the key function of the hormone. Complete the table by filling in the blanks numbered 1 to 8

GlandHormone secretedFunction
1Growth hormone2
thyroid3regulates rate of metabolism
4adrenaline5
6insulin7
8oestrogenreproductive growth and development

Answer

GlandHormone secretedFunction
pituitary gland (1)Growth hormoneregulates growth of body (2)
thyroidthyroxine (3)regulates rate of metabolism
adrenal gland (4)adrenalinehelps to cope with emergency situation (5)
islet of langerhans (6)insulinregulates amount of glucose in blood (7)
ovary (8)oestrogenreproductive growth and development

Label the glands

Question 1

In the figure given alongside, label the glands marked a-e and name the hormones secreted by them.

In the figure given alongside, label the glands marked a-e and name the hormones secreted by them. Endocrine System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 8.

Answer

The labelled glands and the hormones secreted by them are as follows:

a — Pituitary gland (growth hormone)

b — Thyroid gland (thyroxine, calcitonin)

c — Adrenal gland (adrenaline, noradrenaline)

d — Ovaries (oestrogen, progesterone)

e — Testes (testosterone)

Think and Answer

Question 1

Under the universal salt iodization programme in India, the sale of non-iodized salt for human consumption is banned. Why is it so important to eat iodized salt?

Answer

Iodine is very important mineral for human beings. Deficiency of Iodine in the diet leads to low thyroxine hormone in the blood. Under-secretion of thyroxine leads to hypothyroidism. It makes the person sleepy and sluggish, leading to weight gain. It leads to the swelling of thyroid gland, a condition called goitre.
Iodine is not available in ample amount in our diet. In order to ensure proper Iodine intake and avoid hypothyroidism and goitre we must eat only iodized salt. Thus, sale of non-iodized salt for human consumption is banned in India.

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