Lecture 9 - Lecture 9 Endocrine System Endocrine system System of glands that secrete hormones o Messenger molecules o Circulate in blood o Act on

Lecture 9 - Lecture 9 Endocrine System Endocrine system...

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Lecture 9: Endocrine SystemEndocrine system: System of glands that secrete hormonesoMessenger moleculesoCirculate in bloodoAct on distant target cellsTarget cells respond to the hormones for which they have receptorsEffects are dependent on the programmed response of the target cellsBasic categories of hormonesoAmino acid based: modified amino acids (amine), peptides, proteinsoSteroid: lipid molecule derived from cholesterolTypes of CellsoEndocrine: Produces substances that must travel through the bloodstream and take affect at distant sitesoParacrine:Produce substances that affect proximal cellsoAll cells contain specificreceptors that work withcertain substrates destinedfor that site of actionPurely Endocrine OrgansoPituitary glandoPineal glandoThyroid glandoParathyroid glandsoAdrenal glandsEndocrine cells in other organsoPancreasoThymusoGonadsoHypothalamusMechanisms of hormone releaseoHumoral: in response tochanging levels of ions ornutrients in the bloodoNeural: stimulation bynervesoHormonal: stimulation received from other hormonesThe pituitary Gland
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oSits in hypophyseal fossa:depression in sella turcica ofsphenoid boneoSecretes 9 hormonesoAnterior Pituitary (Adenohypophysis or Parsdistalis)FSH: Follicle StimulatingHormoneLH: Luteinizing Hormone ACTH :AdrenocorticotropicHormoneTSH: Thyroid Stimulating HormonePRL: ProlactinGH: Growth HormoneMSH: Melanocyte Stimulating HormoneoPosterior pituitary(Neurohypophysis or Parsnervosa)OxytosinADHHypothalamus controls anterior pituitary hormonereleaseoReleasing hormones/releasing factor: Secretedlike neurotransmitters from neuronal axons intocapillaries and veins to anterior pituitary (adenohypophysis)TRH (thyroid releasing hormone)– initiates release of TSHCRH (corticotropin releasing hormone)– initiatesrelease of ACTHGnRH (gonadotropin releasing hormone)initiates release of FSH and LHPRF (prolactin releasing hormone)– initiatesrelease of PRLGHRH (growth hormone releasing hormone)initiates release of GH oInhibiting hormones of hypothalamusPIF(prolactin inhibiting factor) -turns off PRLGHIH(growth hormone inhibiting hormone) -turnsoff GHoHypothalamus controls secretion of hormones which in turn controls the secretionof hormones by the thyroid gland, the adrenal cortex and gonads: therefore, the brain controls these endocrine glandsPituitary hormones: oTropic hormones that regulate other hormones
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TSH
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