HORMONES- THE ENDOCRINE SYSTEN
1. The endocrine system consists of a number of endocrine glands which secrete chemicals known as hormones.
2. Endocrine system helps in coordinating the activities of our body in addition to nervous system.
3. The hormones produced by endocrine glands act as messengers between the nervous system and the organs of our body.
Features of hormones
1. They are secreted by ductless glands called endocrine glands.
2. They are poured directly into the blood.
3. They are secreted in small amounts by the endocrine glands
4. The hormones have their effect at the site different from the sites where they are made.
5. They act on specific tissues or organs called target tissues or organs.
6. They are known as chemical messengers as they modify and regulate the activity of the target tissues or organs.
The endocrine glands present in the human body areas follows:
Endocrine gland Location
1 Pineal Forebrain
2. Hypothalamus Forebrain
3. Pituitary Forebrain
4. Thyroid wind pipe
5. Parathyroid embedded in the
i. Thyroid gland
6. Adrenal Above kidney
7. Pancreas Below the stomach
8. Testis Male sex organ
9. Ovary Female Sex Organ
1. It is present in the brain.
2. It produces ’releasing hormones’ and ’inhibitory hormones’.
3. The function of hypothalamus is to regulate the secretion of hormones from pituitary gland i.e. hypothalamus controls the pituitary gland.
1. It is also present in the brain.
2. It produces number of hormones. One of the hormones secreted by pituitary gland is growth hormone.
3. The growth hormone controls the growth of the human body. The growth hormone controls the development of bones and muscle.
4. If there is deficiency of this hormone in childhood, it leads to dwarfism. On the other hand, if is secreted in large amount then the person becomes giant.
1. It is attached to the wind pipe our body.
2. It produces a hormone called thyroxin. Iodine is necessary for the thyroid gland to make thyroxin hormone.
3. Thyroxin regulates carbohydrate, protein and fat metabolism of the body.
4. The deficiency of iodine in the diet of a person produces less thyroxin hormone and causes a disease known as goiter. One of the symptoms in this disease is a swollen neck.
1. The pancreas is present just below the stomach in the body. Pancreas secrets the hormone called insulin.
2. Insulin regulates the level of sugar in the blood. If it is secreted in less amount the sugar level in the blood rises, person suffers from diabetes. Diabetes causes many harmful effects.
1. Testes are the male sex organs. They also function as endocrine gland. Testis produces male sex hormone called testosterone.
2. Testosterone controls the development of male sex hormone and the changes which occur during puberty at the age of 13 to 14 years like deeper voice, moustache, beard, and more body hair.
Ovaries are the male sex organs. They also function as endocrine gland. Ovary makes two hormones called estrogen and progesterone.
ESTROGEN: It controls the development of female sex organs, and the changes which occur during puberty at the age of 10 to 12years like feminine voice, mammary glands etc.
PROGESTERONE: It is a pregnancy hormone. It also causes ovulation (release of ovum).
1. It is an emergency hormone or hormones of Fight or Flight. The adrenal gland secrets a hormone called adrenalin.
2. It prepares the body to face emergency conditions of physical stress like danger, anger, excitement; etc.
3. It is secreted in small amounts all the time but in large amounts when a person is frightened. When we are faced with a dangerous situation this hormone….
1. The target organ is heart so heart beat increases, resulting in supply of more oxygen in our muscles.
2. The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in theses organs.
3. Increase blood flow to our skeletal muscles.
4. Increase in the breathing rate.
5. Allows more supply of glucose into the blood to give us a lot of energy quickly to fight or flight from the frightening situation.