Endo 1 - intro

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Endo 1 - intro
2012-01-24 18:16:04

exam 1 review
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  1. Endocrinology can be defined as:
    the study of the regulation and integration of the organ systems of the body by chemical substances called hormones
  2. Neuroendocrinology:
    study of the interactions that allow the brain to exert control over endocrine glands such as the pituitary
  3. Hormones are:
    chemical messengers produced inside specialized endocrine cells/tissues and released by these cells into the body fluids that surround them. In most cases, hormones find their way into the blood vessels and are transported in the bloodstream to a distant site called a target tissue, where they influence the functioning of cells
  4. Properties of a hormone: (11 of them)
    • 1. physiological regulators: not the source of energy
    • 2. effective in minute quanitities (micrograms)
    • 3. synthesized by endocrine cells
    • 4. released directly into bloodstream
    • 5. transported by the circulating blood
    • 6. binding to plasma proteins
    • 7. influences target cells only (tissue selectivity)
    • 8. exert specific actions
    • 9. latent period
    • 10. cells producing hormones are insensitive to them
    • 11. syngergism
  5. Classification of Hormones:
    • Steroid - derived from cholesterol
    • Peptide - polymers of amino acids
    • Amine - derived from amino acids, tyrosine and tryptophan
  6. Steroid Hormones
    • derivatives of cholesterol
    • small molecules (mw around 350-450 daltons)
    • hydrophobic (insoluble in water, soluble in organic/lipid solvents)
    • Examples: gonad hormones (estrogens, androgens), hormones of Adrenal cortex (cortisol), vitamin d metabolites
  7. Peptide Hormones
    • are polymers of alpha-amino acids
    • are often large molecules (mw 10^3 d)
    • are hydrophilic (water soluble)
  8. Amine Hormones:
    • derivatives of amino acids, tyrosine and tryptophan
    • ex: thyroid hormones, epinephrine, melatonin
  9. Tropic hormones
    • stimulate growth of an endocrine gland and often times the synthesis and secretion of increased quantities of another hormone
    • examples: ACTH, TSH, LH, FSH
    • the target tissue of a tropic hormone is another endocrine gland
  10. non-tropic hormones
    • act on non-endogrine tissues to produce changes in their metabolic activities
    • ex: estrogens, androgens, glucocoticoids
  11. Target tissues/cells
    trap or concentrate minute circulating quanities of hormones from the blood and respond to them by increasing or decreasing their metabolic activities
  12. metabolism
    refers to the overall chemical reactions that provide energy and raw material for growth and repair of cells and tissues and the removal of by products of these energy-yielding reactions.
  13. Function of Hormones
    Homeostasis is a state in which concentrations of all intracellular and extracellular chemicals are ideal for the maximum functional efficiency of the organism.
  14. Hormone-like substances
    • wound hormones - agents emanating or secreted wounded or injured tissues
    • phytohormones - growth substances in plants
    • neurohormones - agents released from nerve terminals
    • social hormones - chemical agents released into external environment and serve to influence the behavior of other individuals of the same species (pheromones)
  15. cellular communications
    • endocrine
    • paracrine
    • autocrine
    • neurocrine
  16. glands
    are defined as tissues or groups of cells whose primary function is to secrete or release certain chemical products into the body environment
  17. exocrine glands
    • secretions are enzymes, mucus, and other biochemically active products
    • ex: salivary gland, mammary gland
  18. endocrine glands
    • secretions are hormones
    • ex: thyroid, ovary, pituitary
  19. basic criteria of hormone receptors
    • tissue specificity
    • binding specificity
    • high affinity
    • low tissue concentration
  20. polypeptide-secreting cells
    • large-prominent nuclei
    • small amount of cytoplasm
    • prominent golgi apparatus
    • abundant rough endoplasmic reticulum (RER)
    • large numbers of secretory granules
    • surrounded by blood sinusoids
  21. Steroid-secreting cells
    • small, rounded nuclei
    • large amount of cytoplasm
    • large numbers of lipid droplets (foamy appearance)
    • abundant smooth ER
    • many mitochondria
    • highly vascularized tissue
  22. Assay Requirements
    • sensitive
    • specific
    • reliable
    • simple
  23. In Vitro
    • incubation of unknown sample with endocrine tissues or cells in culture medium
    • measured responses - cAMP (ATP breaks down)
    • measuring the cell count
    • cytochemical changes
  24. In Vivo
    unknown sample is injected in the animal, then measure the particular effect