Greetings Erudite Proponents of the CS art, The term endocrine is used to describe glands that secrete their products internally. For example, thyroid and parathyroid glands are endocrine glands (ductless glands). Certain other glands, such as sebaceous and sweat glands of the skin release their products into ducts that lead to the outside of the body. Glands that secrete externally are called exocrine glands. As a group, the endocrine glands are concerned with the regulation of metabolic processes. They control the rates of certain chemical reactions, and aid in the transport of substances through cell membranes, play vital roles in cell growth, and help regulate water and electrolyte balance. The chemicals secreted by endocrine glands are called "hormones". They are released into the extracellular spaces surrounding the gland, absorbed into the blood and carried to all parts of the body. The physiological effect of a specific hormone is often restricted to a certain tissue, called its target tissue. In other cases, a particular hormone can affect nearly all body cells. Of the twelve major hormone producing glands we will be most interested in the adrenal cortex (outer region of the adrenal gland). Of the over two hundred identified hormones we will concentrate on those that affect the sebaceous and sweat glands. Each kind of hormone has a unique molecular structure and a unique action as well. However, all hormones are organic substances, usually steroids, proteins, or amines. The steroids from the adrenal cortex have controlling effects on the sebaceous and sweat glands. Some other hormones are suspected of affecting the sweat glands also, and research is on going. Although it is not yet totally clear how hormones exert influences on their target tissues, it is recognized that they do so by acting on the cell membranes. According to this idea, each kind of hormone molecule can combine with specific receptor sites located on the membranes of its target cells. Once the hormone-receptor combinations have been made, certain enzyme molecules (adenyl cyclase) are activated within the membrane and diffuse into the cells cytoplasm. There the enzymes cause cytoplasmic ATP (adenosine triphosphate) molecules to be converted into "cyclic AMP" (adenosine monophosphate). The cyclic AMP brings about the desired cellular changes, i.e., secrete more, secrete less, or change secretion content. In other words, a hormone that stimulates activity in a particular target cell may do so by initiating the formation of cyclic AMP. The cyclic AMP, in turn, may cause changes in the cells membrane permeability, in the number of enzyme molecules present, or in the rate at which certain substances are synthesized by the cell----changes recognized as the hormones effect. Now we get to the pituitary gland which is attached to the hypothalamus gland by the pituitary stalk. The pituitary secretions are controlled by the brain which is in turn stimulated by nerve impulses originating in the hypothalamus. The hypothalamus receives information from nearly all parts of the nervous system. This information includes data concerning a persons emotional state, body temperature, blood nutrient concentrations, ionic balance and so forth. The hypothalamus signals the pituitary gland to release hormones. The hormone of interest to us is the ACTH (adrenocorticotropic hormone) which controls the manufacture and secretion of certain hormones from the outer layer, or cortex, of the adrenal gland. The adrenal glands are located atop each kidney. The outer part of the gland is called the adrenal cortex and it produces a number of different hormones, of which about thirty have been identified. These hormones are all steroids, and unlike the medullary (inner adrenal layer) hormones---which a person can live without--- those of the adrenal cortex are vital. In the absence of adrenal cortex secretions a person will die within a week. The hormones from the cortex are in three groups, mineralocorticoids which regulate the concentrations of extracellular electrolytes. Glucocorticoids which influence metabolism of carbohydrates, proteins and fats. Sex hormones which have effects on sexual characteristics. Of the mineralocorticoids which are manufactured by the cells in the outer zone (zona glomerulosa) of the cortex the most important is "aldosterone". It controls the water conservation or promotion by acting on the blood volume and pressure. It also controls balance of sodium and potassium ions in the body. This is accomplished by regulating the urine and sweat. Of the various glucocorticoids, the hormone responsible for the greatest amount of activity is "cortisol" (hydrocortisone), a substance structurally similar to aldosterone. Its action is controlled by the ACTH from the pituitary gland, and effects cell membranes and stimulates liver cells and adipose tissue. As we can plainly see, hormones have control of most bodily functions involving regulation of the homeostasis and the sweat glands play an important role . The sweat glands are controlled by nerve impulses, and hormones.
---to be continued--- Bless you, Bob Lee -- oozing on the muggy shore of the gulf coast [email protected] -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
