Endocrine System in Humans

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.

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.

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.

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.

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.

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

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

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.

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

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

False

Correct statement — Endocrine glands are ductless glands.

False

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

True

False

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

True

The adrenal glands secrete adrenaline and noradrenaline hormones.

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

Adrenaline helps the person cope with an emergency.

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

The testes secrete the male sex hormone called testosterone.

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)

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.

hormones

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

pituitary

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

growth hormone

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

thyroid gland

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

insulin

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

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.

insulin

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

False

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

False

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

True

True

True