endocrine system. types of glands endocrine exocrine

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  • ENDOCRINE SYSTEM

  • TYPES OF GLANDSEndocrineExocrine

  • Endocrine glands; Endocrine tissuePineal glandPituitary glandThyroid glandParathyroid glandsThymusAdrenal glandPancreasOvaries / TestesStomachDuodenumKidney

  • Chemistry of HormonesAmines - simple hormones synthesized from tyrosineProteins and Peptides - chains of amino acids hooked togetherSteroids - lipid soluble hormones derived from cholesterolEicosanoids - hormones derived from arachidonic acid (from lipids)

  • Mechanisms of Hormone ActionAlters plasma membran permeabilityStimulates synthesis of proteinActivates or deactivates enzymesInduces secretory activityStimulates mitosis

  • Lipid Soluble HormonesThyroid and steroid hormones cross the cell membrane and bind to INTRACELLULAR receptors in the cytoplasm or nucleusThe hormone- receptor complex triggers activation or inactivation of specific genesSynthesis of new protein alters cellular activity causing a physiological response

  • Water Soluble HormonesProtein and catecholamine hormones act by binding to receptors located on the cell membranes of target cellsHormones act as the 1st messenger which in turn activates a series of events involving cAMP as the 2nd messengercAMP activates protein kinasesG-proteins link the first messenger and the second messenger

  • Hormone ReleaseHumoral - hormones released in response to changing blood levels

    Neural - nerve fibers stimulate release

    Hormonal - one hormone stimulates the release of another

  • Endocrine Glands

  • Pituitary GlandMaster glandLocated within the sella turcica of the sphenoid boneAssociated closely with the hypothalamusDifferentiated into the anterior pituitary, or glandular portion, the posterior pituitary, or nervous portion and the avascular pars intermedia located in between

  • Posterior lobe - NeurohypophysisConnected with the hypothalamus via the supraopticohypophyseal tractOxtocin (OT)Antidiuretic hormone (ADH)diabetes insipidus

  • Anterior lobe (Adenohypophysis)Controlled by releasing and inhibiting hormones produced by the hypothalamusGrowth hormone (GH)somatotropindwarfism, giantism, acromegalyThyroid - stimulating hormone (TSH)Adrenocorticotropic hormone (ACTH)

  • Acromegaly

  • Anterior lobe of the PituitaryFollicle - stimulating hormone (FSH)

    Luteinizing hormone (LH)

    Prolactin (PRL)

    Melanocyte - stimulating hormone (MSH)

  • Thyroid GlandLocated below the larynx, two lobes connected by an isthmusHormones synthesized from iodine and tyrosineFollicle cells manufacture thyroglobin and store it as colloidTriiodothyronine (T3) / Thyroxine (T4)Goiter, Graves Disease, Cretinism, MyxedemaCalcitonin (CT) - lowers calcium levels

  • Parathyroid glandFour tiny glands located on posterior thyroidParathyroid hormone (PTH)Raises blood calcium

  • Adrenal GlandsLocated retroperitoneally and superior to the kidneyCan be subdivided into outer cortex and inner medulla

  • Adrenal MedullaConsists of hormone-producing cells called chromaffin cellsEpinephrine / Norepinephrine (NE)Sympathomimetic hormonesReleased under stress by direct innervation from the autonomic nervous system

  • Adrenal CortexManufactures steroid hormones called corticosteroidsDivided into three regions: zona glomerulosa, zona fasciculata, zona reticularisZona glomerulosa (outer) - releases mineralocorticoids, principally aldosterone which controls electrolyte balance in the kidneys

  • Adrenal CortexZona fasciculata (middle) - produces glucocorticoids such as cortisol and cortisone; controlled by ACTHAddisons Disease, Cushings DiseaseZona reticularis (inner) - produces adrenal sex hormones such as estrogens and androgensvirilism, gynecomastia

  • Cushings Disease

  • Thymus Pineal GlandLocated posterior to the sternum and between the lungsThymosinLocated in the roof of the 3rd ventricle of the brainMelatonin

  • PancreasLocated posterior and inferior to the stomachBoth exocrine and endocrineIslets of LangerhansAlpha cells - glucagonBeta cells - insulinDelta cells - somatostatinDiabetes mellitus - Type I, TypeII

  • OvariesLocated in the pelvic cavityEstrogensEstradiol, estriol, estroneProgesteroneInhibinRelaxin

  • TestesLocated in the scrotumTestosteroneInhibin

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