DEFINITION Hormones & Endocrine System

Hormones & Endocrine System
 DEFINITIONThe endocrine system consists of a group of organs (sometimes referred to as glands of internal secretion), whose main function is to produce and release hormones directly into the bloodstream.Hormones act as messengers to coordinate the activities of various organs.

Endocrine
The main organs of the endocrine system are:The hypothalamusPituitary glandThe thyroid glandParathyroid glandsThe islands of the pancreasAdrenal glandScrotalOvary.During pregnancy, the placenta also acts as an endocrine gland.
The hypothalamus releases a hormone that stimulates the pituitary; some of which trigger the release of pituitary hormones, and yet others suppress the release of pituitary hormones.
Pituitary gland is sometimes called the authorities because the pituitary gland coordinates many functions of other endocrine glands.Some pituitary hormones have direct effects, while others simply controlling the speed of release of hormones by other organs.Pituitary hormones control the release rate itself through a feedback mechanism, where the other endocrine hormone levels in the blood signals the pituitary to slow down or accelerate the release of hormones.
Not all of the endocrine glands are under the control of the pituitary; some of them respond, either directly or indirectly, to the concentration of substances in the blood:Insulin-producing cells of the pancreas respond to glucose and fatty acidsParathyroid cells respond to calcium and phosphateAdrenal medulla (part of the adrenal gland) responds to direct stimulation of the parasympathetic nervous system.
Many organs that release hormones or hormone-like substances, but usually not mentioned as part of the endocrine system.Some of these organs produce substances that act only at its disposal, while others do not release their products into the bloodstream.For example, the brain produces various hormones whose effects are primarily confined to the nervous system.
Endocrine System

HORMONES
Hormones are substances that are released into the bloodstream from a gland or organ, which affects the activity in the cells.Most of the hormone is a protein consisting of amino acid chains with different lengths. The rest is a steroid, which is a fatty substance which is a derivative of cholesterol.Hormones in very small amounts can trigger the body's response is very broad.
Hormone bound to receptors on the cell surface or inside the cell. The bond between the hormone and the receptor will accelerate, slow down or alter cell function. In the end, the hormone controlling the function of the organ as a whole:Hormones control the growth and development, reproduction and sexual characteristicsHormones affect the way the body uses and stores energy inHormones also control the volume of liquid and water and salt levels in the blood.
Some hormones affect only one or two organs, while other hormones that affect the entire body.For instance, TSH is produced by the pituitary gland and affects only the thyroid gland. While thyroid hormone produced by the thyroid gland, but these hormones affect cells throughout the body. Insulin is produced by pancreatic islet cells and affects the metabolism of sugar, protein and fat throughout the body.

ENDOCRINE CONTROL
If the abnormal function of the endocrine glands, the hormone levels in the blood may be high or low, disrupting body functions.To control the endocrine function, the release of each hormone should be regulated within the limits of the right.The body needs to feel from time to time if it takes more or less hormones.
Hypothalamus and pituitary gland releases hormones if they feel that other hormones that control them are too high or too low.And pituitary hormones into the bloodstream to stimulate the activity of the target gland. If the target gland hormone levels in the blood is sufficient, then the hypothalamus and pituitary gland to know that stimulation is not required anymore and they stopped releasing hormone.Feedback system can control all the glands that are under the control of the pituitary.
Certain hormones that are under the control of the pituitary has a function that has a specific schedule. For example, a woman's menstrual cycle involves increased secretion of LH and FSH by the pituitary gland of each month. Hormones estrogen and progesterone levels in the ovaries also had up and down each month.The exact mechanism of control by the hypothalamus and pituitary to bioritmik is still not understood. But it is clear that the organ responds to a kind of biological clock.
Other factors also stimulate the formation of hormones.Prolactin (hormone secreted by the pituitary gland) causes the milk glands in the breasts to produce milk. The baby's sucking on the nipple stimulates the pituitary to produce more prolactin. The baby's sucking also increase the release of oxytocin which causes milk ducts so that the wrinkle can be applied to the milk the baby's mouth.
Such gland and parathyroid glands pakreas island, not under the control of the pituitary. They have their own system to sense whether the body needs more or less hormones.For example, insulin levels increased immediately after a meal because the body has to process sugar from the diet. If insulin levels are too high, blood sugar levels will drop to very low.
Other hormone levels vary based on the less obvious reasons.Corticosteroid levels and the highest growth hormone found in the morning and lowest at dusk. The reason this happens is not fully understood.

MAJOR HORMONES
The function that produces hormonesAldosterone The adrenal glands help regulate salt and water balance by holding the salt & water supply and disposing of potassiumAntidiuretic hormone(Vasopressin) pituitary glandCauses the kidneys to retain waterTogether with aldosterone, helps control blood pressureCorticosteroids adrenal gland which has a broad effect on the entire body, especially as:Anti-inflammatoryMaintaining blood sugar levels, blood pressure and muscle strengthHelp control the balance of salt and waterControlling the formation of the pituitary gland corticotropin releasing hormone and the adrenal cortexRenal erythropoietin stimulates red blood cell formationControlling the development of the ovaries of estrogen sexual traits and female reproductive systemsPancreatic glucagon increase blood sugar levelsControlling the growth hormone the pituitary gland growth and developmentIncrease the formation of proteinInsulin PancreasLowering blood sugar levelsAffect the metabolism of glucose, protein and fat throughout the bodyLH (luteinizing hormone)FSH (follicle-stimulating hormone) pituitary glandControl of reproductive function (sperm and cementum formation, egg maturation, the menstrual cycleControl of male sexual characteristics and female (the spread of hair, muscle, skin thickness and texture, sound and perhaps even a personality trait)Oxytocin is the pituitary gland causes muscle contractions of the uterus and milk ducts in the breastControl of parathyroid gland parathyroid hormone of bone formationControlling the release of calcium and phosphateThe ovaries of progesterone prepare the uterine lining for the cultivation of which the fertilized egg cellPrepare the mammary glands to produce milkStarting Polaktin pituitary gland and maintain the formation of milk in the mammary glandRenal renin and angiotensin control of blood pressureThe thyroid gland thyroid hormone Set of growth, maturation and metabolic rateTSH(Thyroid-stimulating hormone) stimulates the pituitary gland formation and release of hormones by the thyroid gland