Storage Secretion and Transport of Hormones, The hormones are stored, secretes and transported in the following way.
Hormones are proteins in nature. Peptides specifically contains 3 amino acids to 100 amino acids. When the number of amino acid exceeds from hundred it becomes polypeptids. As they are also proteineous in nature, so these (polypeptides and peptides) are produced by the rER (rough endoplamic reticulum) inside the endocrine cell.
In the synthesis of peptides,the first product formed is called preprohormone. The preprohormone is in inactive form. It is further broken down/ cleaved into prohormone. This reaction is catalyzed by the proteolyric enzymes.
This prohormone is transpirted to golgi apparatus, where the packaging occurs (it is further broken down into active prohormones, surrounded by membrane). The whole structure formed as a result of this packaging is called secretory vesicle. This secretory vesicles has active prohormone and can show its role when released. This will either be present in the trans-face of golgi body or may be attached with the plasma membrane.
By the process of endocytosis it can release its contents when some stimulus arise. The stimulus may be in the form of electrical impulse or tropical hormones or chemical impulse. This secretory vesicles will discharge its secretion by exocytosis into interstitial fluid directly or blood.
Control of hormone secretion rate:
The secretion of hormone is controlled by feedback mechanism. Whenever a hormone in the body is produced more than its normal level, the endocrine glands then control their level. For example; glucose and insulin.
Transport of hormones:
Water soluble hormones are dissolved in plasma and carried to their target cell and then discharged. Specifically polypeptides are included in this category of water soluble hormones.
For example; polypeptides, peptides and insulin.
The steriods and amines are bound to the plasma proteins and are transported in bound form.
For example; globulin and fibrinogen.
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