Bashir A. Lone

Endocrine glands, their hormones, structure, regulation and diseases

Hormones are specific chemical messengers that exert effects at points some distance removed from their sites of production. Hormones may of course diffuse from one place to another but as would be expected in animals with well-developed circulatory systems, most of their transport in mammals is by the blood. The tissues and organs that produce and release hormones are termed endocrine tissues and endocrine organs. The use of the word “endocrine” i.e.

Action Potential and Synaptic Transmission

An action potential is a transient depolarization of the membrane potential of excitable cells. They serve two main functions: to transmit and encode information, and to initiate cellular events such as muscular contraction. An action potential results from a transient change to the properties of the cell membrane, from a state where it is much more permeable to K+ than Na+, to a reversal of these permeability properties. Thus during the action potential an influx of Na+ is responsible for the rapid depolarization and an efflux of K+ causes repolarization.

General mechanism of hormone action

The endocrine system is a control system of ductless glands that secrete hormones within specific organs. Hormones act as "messengers" and are carried by the bloodstream to different cells in the body, which interpret these messages and act on them. It seems like a farfetched notion or idea that a small chemical can enter the bloodstream and cause an action at a distant location in the body. Yet this occurs in our bodies everyday of our lives. The ability to maintain homeostasis and respond to stimuli is largely due to hormones secreted within the body.

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