Tag: mechanism of hormone action

Steroid hormones are a group of hormones, that belong to the class of chemical compounds known as steroids; they are secreted by three steroid glands, the adrenal cortex, testes and ovaries, during pregnancy by the placenta. All steroid hormones are derived from cholesterol. They are transported through the bloodstream to the cells of various target organs, where they carry out the regulation of a wide range of physiological functions.

Though hormones are released into the blood stream and hence can reach all cells, yet they affect only those cells which have hormone specific receptors. Thus, binding of hormone to receptor is crucial irrespective of presence of receptors inside the cell or on its surface. Thus, options A and D are incorrect as the absence of receptors renders the cell unaffected by hormonal action. Option B is incorrect as hormone-receptor binding is an essential step in hormonal action. Thus, in absence of receptors, the target organ will no longer respond to the hormone. Hence, the correct answer is option C.

Glucose (C$ _{6}$H$ _{12}$O$ _{6}$) is the essential constituent of human blood and is a simple sugar component of carbohydrates. It exists in both the open chain structure and closed cyclic ring form. The open chain structure has a straight chain of six carbon atoms with the presence of an aldehyde group at its end but it fails to undergo aldehydic reactions. This is because the glucose ring is not very stable and can be easily broken by strong reagents like HCN to give the intermediate aldehyde form which reacts with them just like an aldehyde. But weak reagents like NH$ _{3}$ are unable to open the chain and cannot react with it. This explains the inability of glucose to form aldehyde and ammonia. So, the correct option is "an open chain present ends with functional groups (in this case aldehyde), and glucose failed to undergo typical aldehyde reactions, a phenomenon that could be explained by having no end functional group in a ring structure".

• A tropic hormone is a hormone that stimulates an endocrine gland to grow and secrete its hormones. (One hormone causes another hormone to do something) 
• In humans, tropic hormones are secreted by the adenohypophysis(anterior pituitary gland). Hence, A hormone that stimulates an endocrine gland to grow and secrete its hormone is known as Tropic hormones

Receptor is a molecule usually found on the surface of a cell, that receives chemical signals from outside the cell. When such external substances bind to a receptor, they direct the cell to do something, such as divide, die, or allow specific substances to enter or exit the cell.

Receptors are proteins embedded in either the cell's plasma membrane (cell surface receptors), in the cytoplasm, or in the cell's nucleus (nuclear receptors), to which specific signaling molecules may attach.

• In both males and females have glandular tissue within the breasts however, in females the glandular tissue begins to develop after puberty in response to estrogen release. 
• Mammary glands only produce milk after childbirth. During pregnancy, the hormones progesterone and prolactin are released. Hence, Estrogen, Prolactin and Progesterone help in the formation of alveoli of the mammary glands.