The Endocrine System

The Endocrine System

The controlled process of ductless glands which secrete chemical information generally called as hormones which circulate within the body through the bloodstream to affect distant cells within specific organs is commonly known as the endocrine system. The types products secreted by endocrine gland is immediately into the blood or interstitial fluid, without the storage of the chemical. The produced hormones serve as "messengers," and these type of hormones are carried by the bloodstream to several cells in the body, which construe that messages and follow on them.

It looks like a farfetched information that the distant location in the body is caused by the entry of a small chemical into the blood stream. Every day of our lives this process occurs in our bodies . The quantity of being able to maintain homeostasis and respond to stimuli is hugely due to the hormones secreted by glands within the body. We are not able to grow, maintain a constant temperature, produce offspring, or perform the basic actions and functions that are essential for life without the absence of hormones.

The Electrochemical connection from the hypothalamus of the brain to all the organs which control the body metabolism, growth and development, and reproduction is provided by the endocrine system.

Major types of hormones secreted in the endocrine system are as follows:

(1) Steroidal and

(2) Nonsteroidal, or protein based hormones.

Through negative feedback of hormones is regulated by the endocrine system, except in very rare cases like childbirth. The production of the hormone is decreased by the increase in hormones activity. The particular quantity to control factors also, altogether keeping constant levels of hormones is provided by the immune system and other factors.

Types of Glands

Those types of the gland which release their cellular secretions through a duct that empties to the outside or into the lumen of an organ is commonly known as Endocrine glands. This type of gland consists sweat glands, salivary and pancreatic glands, and mammary glands. Which are not considered a part of the endocrine system

The glands which have no duct are generally called Endocrine Glands and this type of glands release their secretions directly into the intercellular fluid or into the blood. The endocrine system makes up the collection of endocrine glands.

The main types of endocrine glands are the pituitary such as anterior and posterior lobes, thyroid, parathyroids, adrenal (cortex and medulla), pancreas and gonads.

The pituitary gland is connected to the hypothalamus of the lower forebrain.

Two lateral masses, attached by a cross bridge, which are connected to the trachea. The larynx is slightly inferior.

Four masses of tissue are contained by parathyroids, among them, two embedded posteriorly in each lateral mass of the thyroid gland.

One adrenal gland is situated on top of each kidney. The cortex is the outer layer of the adrenal gland. The medulla is the inner core.

The pancreas is along the lower curvature of the stomach, close to where it meets the first region of the small intestine, the duodenum.

The gonads are found in the pelvic cavity.

Hormones and Types

The type of chemical signal which is generally known as hormones. Which are a means of communication between the cells.

The hormones secreted by the endocrine system are instrumental in maintaining homeostasis and controlling the reproduction and the development. The chemical messenger is generally known as hormones which are secreted by a cell that effects special disorder in the cellular activity of target cells. Differently the substances produced by the gland like saliva, milk, stomach acid and digestive enzymes is the endocrine gland. The endocrine glands are not able to produce substances into tubes. The endocrine glands produce straightly their hormones into the surrounding extracellular space. The hormones then move out into nearby capillaries and are transported throughout the body in the blood.

There is the same process of the mechanism of working of the endocrine and nervous systems. The endocrine and nervous systems influence other cells with the help of chemicals like hormones and neurotransmitters. Still, they carry through their goals in another and different manner. Neurotransmitters act within milliseconds on adjacent muscle, gland, or other nervous cells, and their effect is short-lived. Hormones take longer to produce their intended effect, may affect any cell, nearby or distant, and produce effects that last as long as they remain in the blood, several hours should be taken by them.

1. Amino acid-derived: The amino acids are modified by hormones.
2. Polypeptide and proteins: Hormones which are chains of amino acids of less than or more than about 100 amino acids, respectively. Some protein hormones are actually glycoproteins, containing glucose or other carbohydrate groups.
3. Steroids: The lipids which are synthesized from cholesterol. Four interlocking carbohydrate rings is characterized by steroids.
4. Eicosanoids: They are the lipids which are synthesized from the fatty acid chains of phospholipids which are found in the plasma membrane.

The interstitial fluids are diffused by hormones circulating in the blood which surrounds the cell. Specific receptors having cells for a hormone respond with an action which is suitable for the cell. The reason of the specificity of hormone and target cell, the effects produced by a single hormone and different kinds of target cells may vary among them.

One of two methods is used to activate hormones of target cells, depending upon the chemical nature of the hormone.

• Steroid hormones and hormones of the thyroid gland which are the lipid-soluble hormones which diffuse the target cells through the cell membranes. The lipid-soluble hormone receptor is bound by the protein that, in turn, activates a DNA segment which turns on specific genes. The transcription of the genes is the result of the production of the protein and which regulate specific physiological cell activity is a subsequent translation of mRNA act as enzymes.
• Polypeptide, protein, and most amino acid hormones are water soluble hormones which bind to a receptor protein on the plasma membrane of the cell. The receptor protein, in turn, excites the production of one of the following second messengers:

When the receptor protein activates another membrane-bound protein then the Cyclic AMP is produced and is generally called a G protein. The adenylate cyclase is activated by the G protein, the enzyme that catalyzes the production of cAMP from ATP. The enzyme is triggered out by Cyclic AMP which generates specific cellular changes.

The membrane phospholipids produce Inositol triphosphate. IP3, in turn, triggers the release of CA2+ from the endoplasmic reticulum, which then activates enzymes that generate cellular changes.

References

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