Exam 5 Review:  Chapter 16:  General Endocrine Terminology

endocrine gland - A ductless gland, e.g., the thyroid or the pituitary glands, which produces one or more hormones which will be released into the bloodstream to be distributed body wide in order to interact with their target cells, tissues, and organs.

endocrine system - The glands and parts of glands which produce endocrine secretions, i.e., hormones, which help to integrate and control bodily metabolic activity and physiological functions; e.g.,. the pituitary, thyroid, parathyroids, adrenals, pancreatic islets of Langerhans, ovaries, and testes.

endocrinology - The science dealing with the endocrine glands and their diseases.

hormone = endocrine substance - a regulatory molecule, produced by an endocrine gland or endocrine or neuroendocrine cell, which is secreted into the blood stream to circulate widely in the body to interact with their target cells, tissues, and organs in order to integrate and control their metabolic activity and physiological functions; hormones may be made from cholesterol, the steroids, or from amino acids, the amine, peptide and protein hormones.

neuroendocrine system - Complex control systems in the body where the nervous system and one or more endocrine organs or tissues cooperate closely to regulate and control the metabolic activity and physiological functions of specific target cells, tissues, or organs; e.g., the cooperation between the hypothalamus and each lobe of the pituitary gland, and the cooperation between the sympathetic division of the ANS and the adrenal cortex.

target cells - Cells which are acted upon selectively by a specific agent, e.g., a hormone, local hormone, neurotransmitter, a drug, or a virus; target cells for neurotransmitters have cell surface receptors which bind to the neurotransmitter;  target cells for hormones have cell surface receptors or cytoplasmic receptors which bind to the hormones.

cell surface receptor - An integral or peripheral membrane protein of a target cell's plasmalemma which has an affinity for and will bind noncovalently and reversibly with a specific molecule, which may be a part of a hormone, local hormone, neurotransmitter, a drug, or a virus; cell surface receptors for hormones and local hormones generally activate one or more internal second messenger systems to effect the regulatory change controlled by the arrival of the hormone or local hormone.

cytoplasmic receptor - A cytoplasmic protein of a target cell which has an affinity for and will bind noncovalently and reversibly with a specific molecule, which may be a part of a hormone, local hormone, neurotransmitter, a drug, or a virus; cytoplasmic receptors for hormones, usually steroid hormones or thyroid hormones, generally form a complex which migrates to the nucleus to bind with specific portions of a DNA molecule, i.e., a chromosome, in order to activate one or more genes which will be translated to form new proteins which will effect the regulatory change controlled by the arrival of the hormone.

down-regulation - A reduction in the number of receptors for a control substance, e.g., a hormone, local hormone, neurotransmitter, or a drug, in response to a prolonged excess of the control substance; this is an internal adjustment which usually helps restore homeostasis in a disease state.

up-regulation - An increase in the number of receptors for a control substance, e.g., a hormone, local hormone, neurotransmitter, or a drug, in response to a prolonged decrease of the control substance; this is an internal adjustment which usually helps restore homeostasis in a disease state.
 

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