Chemical Coordination And Integration Class 11 Notes Biology Chapter 22 - CBSE

Chapter : 22

What Are Chemical Coordination And Integration ?

Endocrine, Exocrine Glands And Hormones

Endocrine glands pour their secretion directly into blood. These glands lack ducts, so these glands are called ductless glands whereas the gland with duct is called exocrine gland which secretes enzyme etc. Substances secreted by endocrine glands are known as hormones.

Classification Of Hormones

  • Peptide, polypeptide, protein hormones: E.g. insulin, glucagon, pituitary hormones, hypothalamic
    hormones etc.
  • Steroids: E.g. cortisol, testosterone , estradiol and progesterone.
  • Iodothyronines (thyroid hormones).
  • Amino-acid derivatives: E.g. Adrenaline, nor-adrenaline.

Human Endocrine System

The endocrine glands and hormone producing tissues/cells are located in different parts of the body. The major glands that form human endocrine system are the hypothalamus, pituitary gland, pineal, thyroid, parathyroid, thymus, adrenal gland, pancreas, testes and ovaries.

Summary of Some Major Endocrine Glands

Gland Location Secretion Function Hypo-secretion Under secretion Hyper- secretion over secretion
1. Thyroid On the either side of the root of trachea. They are joined by a narrow Isthmus. 1. Thyroxin It regulates the basal metabolism i.e., the rate of cellular oxidation resulting in heat production. Simple goitre enlargement of thyroid cretinism. Dwarfism and mental retardation, myxedema swelling on face and hands, sluggishness. Exophthalmic goitre, protruding eyes, increased metabolism shortness of breathe, restlessness.
2. Calcitonin Regulates calcium and phosphate levels in the blood. Tetany
2. Adrenal gland Situated on upper part of each kidney.
(i) Adrenal medulla (Central Medulla) Adrenaline or (Epinephrine) or (Emergency hormone) Heart beats faster. It constricts blood vessels
(i) It constricts the arterioles of digestive system.
(ii) Constricts the arterioles of the skin.
Prolonged fight or flight symptoms which wears down the individual.
(ii) Adrenal cortex Cortisone Regulates metabolism and helps body to adjust the stress. Prepuberty males develop female secondary sex characteristics and vice-versa. In adults, results in acute change in secondary sex characteristics in young ones causes, adrenal virilism.
Pancreas (i) Duct gland Slightly below the stomach Pancreatic juice (Exocrine gland) Poured in the duodenum for digestion.
(ii) Ductless gland Islet of Langerhans (Endocrine gland) (i) Insulin (from Beta cells) Diabetes (Diabetes mellitus) Insulin shock
(ii) Glucagon (alpha cells) Raises blood sugar level
(iii) Somatotrophin (delta cells) Inhibits secretion of insulin and glucagon.
(i) Testis (Male) In the scrotum Testosterone and androsterone Development of primary and secondary sex characteristics in males influences sexual instincts and reflexes.
(ii) Ovary (female) In the pelvic cavity (i) Oestrogens Development of primary and secondary sex characteristics in females.
(ii) Progesterone Prepares the uterus for the implantation, retention and growth of the foetus.
(iii) Relaxin Helps to dilate the cervix towards the end of pregnancy to enable child birth.

Hormones Of Pituitary Gland

Gland Location Secretion Function Hypo-secretion Hyper-secretion
1. Pituitary gland (master gland) Attached to the hypothalamus of the brain.
(i) Anterior lobe 1. Human Growth Hormones (HGH) Stimulates general body growth. In childhood dwarfism In childhood Gigantisms in adult Acromegaly.
2. Trophic hormones Stimulate certain other endocrine glands.
(i) Thyroid stimulating hormone (TSH) Control the activities of thyroid gland.
(ii) Adrenocorticotrophic hormones (ACTH) Stimulate adrenal cortex. Insulin shock.
(iii) Gonadotrophic hormones Stimulate testes and ovaries to produce gametes.
(iv) Luteinizing hormone (LH) Stimulate the formation of corpus luteum to produce female hormone progesterone, and testes to produce male hormone.
3. Prolactin Promotes lactation (milk formation and secretion).
(ii) Posterior lobe 1. Vasopressin Increases reabsorption of water from kidney tubules. Diabetes insipidus (Water diabetes)
2. Oxytocin Stimulates the muscles of the uterus to contract during labour.

Hormones are the chemical messengers as they function at a site far away from its place of origin.

Islet Of Langerhans

It is the group of polyhedral cells in the pancreas having endocrine functions. Epinephrine is called emergency hormone.

Hormone Full name
STH Somatotropic Hormone
ACTH Adrenocortico Tropic Hormone
ADH Antidiuretic Hormone
GTH Gonadotrophic Hormone
FSH Follicle Stimulating Hormone
LH Luteinizing Hormone

Pituitary Gland

It is also known as master gland or Hypophysis.


It is the process of removal of testis or ovary from the animals.

Endocrine Gland

Gland that secretes hormones into the blood stream in order to regulate life processes is known as endocrine gland. In humans, the main endocrine glands are the pituitary, thyroid, adrenal, pancreas and gonads.

Hormonal Disorders

  • Dwarfism: Growth hormone deficiency (GHD), also known as dwarfism or pituitary dwarfism, is a condition caused by insufficient amounts of growth hormone in the body.
  • Acromegaly: It is a rare condition where the body produces too much growth hormone, causing body tissues and bones to grow more quickly.
  • Cretinism: Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-mutism, etc.
  • Simple/Colloid Goiter: If there is deficiency of iodine in food then thyroid try to absorb more and more iodine from blood and increases its size it is called simple goiter. It is due to hypothyroidism.
  • Exopthalmic Goiter: It is a form of hyperthyroidism, characterised by enlargement of the thyroid gland,
    protrusion of the eyeballs, increased basal metabolic rate, and weight loss also called Graves' disease.
  • Diabetes: It is caused by the hyposecretion of insulin hormone by pancreas.
  • Addison's Disease: It is characterised by hypoglycemia, acute weakness, increased susceptibility to stress and fatigue. It is also characterised by the hyperpigmentation/bronzing of skin.