The glands without ducts are called ductless glands. Endocrine glands are ductless, and they release chemical fluids called hormones that are responsible for intercellular communication. These hormones do not have any nutrient content and are produced in small quantities. Vertebrates have more endocrine glands. There are primary and secondary endocrine glands. Hypothalamus, pituitary, adrenal are some of the important endocrine glands. 

Exocrine glands release secretions into ducts. The secretions are called enzymes. These glands control sweat, enzyme formation, etc. And these are directly released into the blood.

The whole system of cells, tissues, and the endocrine glands together for the endocrine glands. They are the hypothalamus, pituitary, pineal, thyroid, etc. Some important are:

1. Hypothalamus: They are located in the front portion of the brain. They have neural cells from which control the pituitary glands and release Pituitary hormones. The hypothalamus releases two types of hormones, one of which stimulates the pituitary gland, called releasing hormones. An example of this is gonadotropin. The second one is inhibiting hormones which suppress the working of the pituitary gland. Somatostatin belongs to this category. Hypothalamic neurons activate the axons and release the necessary hormones through the nerve ends. 

2. Pituitary Gland: The pituitary gland located in the brain has two sections. The anterior pituitary secretes hormones like prolactin, growth hormone, adrenocorticotropic, and luteinising hormones. It also releases stimulating hormones for the thyroid and follicles. Whereas the posterior one releases stimulating hormones for melanocytes. The growth hormones released in excess would cause Acromegaly and Gigantism. And if it is not released in sufficient amounts, it causes dwarfism. 

The pituitary gland has three sections. These are the pars distalis, pars intermedia and pars nervosa. The pars distalis releases six tropic hormones. Pars intermedia secretes only a single hormone, and pars nervosa releases two hormones.

1. Pineal Gland:
   These particular glands in the right brain release melatonin, which controls the body’s circadian rhythm. They also affect the body cycle and defence mechanism. Pigmentation, sleep cycle, and temperature control are examples of some of its functions. 
2. Thyroid Gland:
   The thyroid gland is situated in the trachea, and it releases thyroxine and Triiodothyronine. The mineral iodine is responsible for the functions of the thyroid. Lack of iodine in the body causes hypothyroidism. And if it is taken excessively through food results in hyperthyroidism. Hypothyroidism causes enlargement of the thyroid called goitre.  Hyperthyroidism results in weight loss, metabolism called Graves’s disease. The hormones result in metabolic rate, growth of blood cells, controlling metabolism and protein. 
3. Parathyroid gland:
   There are four parathyroid glands situated beside the thyroid. Calcium ions help these glands to secrete parathyroid hormone. It balances the calcium ions in the body. This calcium helps in the strength of bones and teeth. 
4. Thymus:
   The thymus is a gland in the lungs. It secretes thymosins that help in immunity. Thymosins differentiate lymphocytes and support Cell-mediated immunity. The antibodies produced by the thymosins support humoral immunity. The thymus degenerates in old people, causing immunity issues.  
5. Adrenal Gland:
   The adrenal gland is a pair of glands in the kidney. Their deficiency causes Addison’s disease. Adrenaline and noradrenaline are emergency hormones that help in coping mechanisms. They are released from this gland. These are helpful for sweating, heart rate, alertness, etc. They generate glucocorticoids and mineralocorticoids, which helps in lipolysis, blood pressure regulation, and inflammatory responses. The mineralocorticoids are responsible for water and electrolyte regulation.  
6. Pancreas:
   The pancreas is both endocrine and exocrine. As the endocrine, Islets of Langerhans are composed of alpha and beta cells which release glucagon and insulin, respectively. Glucagon controls glucose levels, and insulin enhances glucose intake. Insulin deficiency causes Diabetes Mellitus. Glucagon is responsible for the stimulation of glycogenolysis. Gluconeogenesis results in hyperglycemia. Whereas insulin results in hypoglycemia. 
7. Testis:
   The testis is a male sexual organ that secretes androgens, testosterone. It is the primary sex organ in males. It is made up of seminiferous tubules and stromal or interstitial tissue. Leydig Cells produce androgens. These control the growth of muscles, sexual characteristics, hair growth, etc. These also affect carbohydrate and protein metabolism.
8. Ovary:
   Ovaries are glands in the female abdomen. It secretes steroid hormones like estrogen and progesterone. Estrogen produced by the ovarian follicles controls the growth of sex hormones and sexual developments. Progesterone is formed from the ovarian follicles ruptured after ovulation. Progesterone controls pregnancy and lactation.

Hormones are secreted from tissues of the heart, kidney, and gastrointestinal tract. The organs and the hormones released from them are given here in the table.

Organ	Part	Hormone	Function
Heart	Atrial wall	atrial natriuretic factor	Decreases Blood Pressure
Kidney	juxtaglomerular cells	erythropoietin	Formation of Red Blood Corpuscles
gastro-intestinal tract	Endocrine cells	Gastrin,	Hydrochloric acid and pepsinogen
gastro-intestinal tract	Endocrine cells	Secretin	secretion of water and bicarbonate ions
gastro-intestinal tract	Endocrine cells	Cholecystokinin	secretion of pancreatic enzymes from the pancreas and  bile juice from the gallbladder
gastro-intestinal tract	Endocrine cells	gastric inhibitory peptide	gastric secretion and motility
Non-endocrine cells		Growth hormones	Growth and respiration of tissues

Hormones are released from an organ for a specific target. These targets have hormone receptor proteins. These proteins can hold these hormones and form a hormone-receptor complex. Its formation is responsible for biochemical changes and controls physiological processes. The hormones stay in the complex and generate secondary agents like cyclic AMP CCa++, which regulates metabolism. These regulate genes and chromosomes, and this process as fundamental causes changes in the body.

Type of hormones	Examples
Peptide, Polypeptide, Protein hormones	Insulin, pituitary hormones, hypothalamic hormones, glucagon
Steroids	cortisol, estradiol, testosterone, and progesterone
Iodothyronines	thyroid hormones
Amino-acid derivatives	epinephrine

1. What are the essential concepts discussed in Chapter 22, Chemical Coordination and Integration?

Endocrine glands, hormones released from them, and their uses are the first important thing to be understood from the chapter. Hormones and hormone-receptor complex formation and coordination is the next important thing. The main glands like the adrenal, hypothalamus, pituitary, thyroid are related to various hormone secretions. The deficiency or excess of these hormones leads to various health-related issues. These should be noted and learned to score well in exams.

2. What are Endocrine Glands?

The glands responsible for growth, metabolism, and other special functions that release specialised chemicals called hormones are the endocrine glands. It is a system that is responsible for chemical coordination among cells and communication between the organs. Some examples are the thymus, pituitary gland, Adrenal gland, etc. 

3. Difference Between Endocrine Glands and Exocrine Glands.  

Endocrine glands are glands that release hormones into the blood. It doesn't encompass a duct. Hence it is called a ductless gland. Exocrine glands, on the other hand, have a duct to release secretions. Exocrine glands release secretions for lubrication, excretion, etc. Endocrine glands are hormones for specific purposes and target specific tissues.

4. Does this site contain chemical coordination and integration NCERT solutions? 

Yes, you can find answers to all the chemical control and coordination questions NCERT Chapter 12 in detail. This helps you attempt and practice more questions in the scope of this chapter. Practising exercises is the key to scoring well in competitive examinations. Step-to-step solutions are available here for you to be able to follow the contents very effectively.