The endocrine system is a group of interacting glands and tissues that pro- duce and secrete chemicals to initiate and maintain body functions.

Hormones are chemical signals released by endocrine cells, which travel in the bloodstream to all parts of the body.

Hormones are made and secreted mainly by organs called endocrine glands.

The hormone can travel by the circulatory system to all parts of the body, but only some types of cells, called target cells, have receptors for that specific hormone.

Specialized neurons called neurosecretory cells perform functions in both endocrine and the nervous system.

3.The final relay molecule activates a protein that carries out the cell’s response, which may occur in the cytoplasm or in the nucleus .

4.The binding to DNA stimulates gene regulation, turning genes either on or off.

Endocrine disruptors are substances that interfere with the endocrine system’s normal functions.

Such chemicals can potentially enter animal cells, altering the normal ratio of sex hormones.

Melatonin - participates in regulation of biological rhythms.

Multiple hormones from the hypothalamus directly control the pituitary gland.

Thyroid hormone - stimulates and maintains metabolic processes.

Many hormones affect the activity of other endocrine glands and cells of the body.

Oxytocin - stimulates contraction of uterus and mammary gland cells.

Antidiuretic hormone (ADH) - promotes retention of water by kidneys.

Androgens - support sperm formation; promote development and maintenance of male secondary sex characteristics.

Estrogens - stimulate uterine lining growth. They promote development and maintenance of female secondary sex characteristics.

Epinephrine and norepinephrine - raise blood glucose level. They also increase metabolic activities. And lastly, they constrict certain blood vessels.

Mineralocorticoids - increase blood volume and blood pressure.

The pineal gland, a pea-sized mass of tissue near the center of the brain, synthesizes and secretes melatonin, a hormone that links environmental light conditions with biological rhythms, particularly the sleep- wake circadian rhythms.

The hypothalamus is the main control center of the endocrine system.

The pea-sized pituitary gland consists of two distinct parts: a posterior lobe and an anterior lobe.

The posterior pituitary is composed of nervous tissue and is actually an extension of the hypothalamus.

the anterior pituitary is an endocrine gland that both synthesizes and secretes hormones.

A releasing hormone stimulates the anterior pituitary to secrete more specific hormones and an inhibiting hormone induces the anterior pituitary to stop secreting more specific hormones.

Thyroid-stimulating hormone (TSH) regulates hormone production by the thyroid gland.

Prolactin (PRL) directly stimulates the mammary glands to produce milk. It has diverse effects in other vertebrates, such as the promotion of reproductive-related behaviors in birds and amphibians and the regulation of water balance in fish

The hypothalamus secretes a releasing hormone known as TSH-releasing hormone.

Thyroid hormone performs several important homeostatic functions and stimulates metabolism in virtually all the tissues of the body.

Insufficient iodine in the diet can cause goiter, an enlargement of the thyroid.

The gonads, or sex glands, secrete sex hormones in addition to producing gametes.

In human, estrogens maintain the female reproductive system and promote the development of female features including breasts and wider hips.

In all mammals, progesterone is primarily involved in preparing and maintaining the uterus to support an embryo.

Mostly, androgens stimulate the development and maintenance of the male reproductive system

It secretes digestive enzymes into the small intestine.

They are said to be antagonistic hormones because the effects of one oppose the effects of the other.

Diabetes mellitus is a serious hormonal disorder caused by the body’s inability to produce or use insulin, thereby decreasing the absorption of glucose from the blood.

Hyperglycemia is an elevated level of blood glucose.

Hypoglycemia is when blood glucose level drop below normal.

Adrenocorticotropic hormone (ACTH) stimulates cells of the adrenal cortex to synthesize and secrete a family of steroid hormones called the corticosteroids.

Mineralocorticoids act mainly on salt and water balance.

Glucocorticoids function mainly in mobilizing cellular fuel. It promote the synthesis of glucose from noncarbohydrates such as proteins.

Oxytocin plays a part in mammalian social behaviors.