Medical Books and Lectures notes - Free downloads

Homeostasis - maintains body's internal environment within a set of normal parameters Intrinsic regulation - cell/tissue/organ adjusts itself to environmental change Extrinsic regulation - nervous or endocrine systems adjust cell/tissue/organ to environmental change and coordinate other systems, requires long distance communication Nervous system - rapid, short-term, specific effect, limited targets; gap or synaptic Endocrine system - slower, long-term, broad effect, more targets; chemical messengers Exocrine glands - glandular cells secrete products into ducts Endocrine glands - glandular cells secrete products into ECF around gland Neuroendocrine - secreted by neuron endings into ECF Hormones Chemical messengers produced by endocrine glands which are usually carried in the circulatory system ...

Hormones are the chemical messengers of the body. They are defined as organic substances secreted into blood stream to control the metabolic and biological activities. These hormones are involved in transmission of information from one tissue to another and from cell to cell. These substances are produced in small amounts by various endocrine (ductless) glands in the body. They are delivered directly to the blood in minute quantities and are carried by the blood to various target organs where these exert physiological effect and control metabolic activities. Thus frequently their site of action is away from their origin. Hormonesare required in trace amounts and are highly specific in their functions. The deficiency of any hormones leads to a particular disease, which can be cured by administration of that hormone. Classification of Hormones Hormones are classified on the basis of (i) their structure (ii) their site of activity in the cell. Steroids on which the above classification is...