Physiology - Endocrine - HYPOTHALAMUS & PITUITARY GLAND

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  1. Hypothalamus is a part of central nervous system. It acts as an interface between ______. One of its functions is to control ________.
    • the brain and endocrine system
    • pituitary gland
  2. Pituitary gland is composed of __________. It receives _________ from the hypothalamus and secretes _____ that circulate to the rest of the body.
    • distinct neural and endocrine tissues
    • both neuronal and endocrine signals
    • hormones
  3. Three modes of hypothalamic control over the endocrine system
    • neuroendocrine over anterior lobe of pituitary gland
    • neuroendocrine via posterior lobe of pituitary gland
    • direct neural control (sympathetic) over the endocrine cells of the adrenal medullae
  4. Hypothalamic neurons secrete both regulatory hormones that control the release of a second hormone from endocrine cells in the _______ and hormones directly into ____ in the ______.
    • anterior pituitary gland
    • the blood
    • posterior pituitary gland
  5. The hypothalamus/pituitary serves as an interface for inputs from the brain and ______ to control body functions through endocrine regulation; affect almost every other organ system of the body.
    hypothalamic regulatory centers
  6. Pituitary hormones directly regulate:
    • Water Balance - kidney
    • Metabolic Rate
    • Lactation - mammary gland
    • Milk Secretion - mammary gland
    • Body Growth
  7. Behaving as a master gland, pituitary hormones control the secretion and growth of the following endocrine glands:
    • Thyroid Gland
    • Adrenal Glands
    • Reproductive Glands
  8. Posterior pituitary, (________) is ______ in origin and contains __________ that release hormones into the ___.
    • neurohypophysis
    • neural
    • axons that project directly from the hypothalamus to nerve terminals
    • blood
  9. Anterior pituitary (_______) contains ____ cells regulated _________ signals from the _______ that are released in the _______.
    • adenohypophysis
    • endocrine
    • indirectly by neuroendocrine
    • hypothalamus
    • median eminence
  10. The posterior pituitary, also know as the ________, is derived from _______.
    • neurohypophysis
    • neuroectoderm
  11. The anterior pituitary, also know as the ________, is derived from ______. Axons from _______ terminate in a ______ region, the median eminence, where they secrete regulatory (releasing and inhibiting) hormones into a local circulation that delivers ____ concentrations to the anterior pituitary.
    • adenohypophysis
    • oral ectoderm
    • hypothalamus
    • neurovascular
    • high
  12. Posterior pituitary ‐ Hormones are transported within _____ from ______ and stored at _____ in _______. Release occurs in the ______ of the posterior pituitary.
    • axons
    • cell bodies in the hypothalamus
    • nerve terminals
    • posterior pituitary
    • separate blood supply
  13. Anterior pituitary – Hormones from the ______ are secreted in ________ and pass through _____ to the anterior pituitary, where they regulate pituitary gland _______, which secrete secondary hormones that pass into the general circulation.
    • hypothalamus
    • median eminence
    • the portal vein
    • endocrine cells
  14. Hormones released from the posterior pituitary are referred to as _______, including:
    • neurohormones
    • Vasopressin (antidiuretic hormone, ADH)
    • Oxytocin
  15. Vasopressin (also know as antidiuretic hormone, ADH) plays a key role in _______.
    the regulation of body fluid volume by enhancing the retention of free water by the kidney
  16. Oxytocin's primary role is to _______. Also can _______.
    • stimulate the ejection of milk from the lactating mammary gland
    • stimulate contraction of the uterus
  17. feedback inhibition on vasopressin secretion
    increased ECF osmolarity -> increased ADH secretion -> increased water retention -> dilution of ECF
  18. _____ relationship between plasma vasopressin (ADH) and plasma osmolality.
    _____ relationship between vasopressin level and blood volume/pressure.
    • Positive
    • Negative
  19. Deficiency of vasopressin (ADH) causes ______.
    diabetes insipidus
  20. As a consequence of disease or trauma, the neurons responsible for secreting vasopressin (ADH) can be damaged. Failure to secrete sufficient vasopressin to maintain normal plasma osmolality causes _______.
    Urine volume can reach 1000 ml/hr
    osmolalities as low as 50 mOsm/kg
    frequent urination
    drink large volumes of water (_____) to prevent collapse from volume depletion and hyperosmolality.
    • excessive loss of water in urine
    • polydipsia
  21. Treatment with _____ provides rapid relief for diabetes insipidus.
    vasopressin
  22. ______ stimulates oxytocin release through afferent sensory neuronal signals to the ______. Oxytocin is released into the circulation and causes ________.
    • Suckling
    • hypothalamus
    • contraction of cells that line the breast ducts, resulting in milk ejection
  23. In pregnancy, oxytocin release is stimulated at ____ by _________, which elicit neuronal signals to the ________ to induce oxytocin release. Oxytocin acts to _______.
    Oxytocin also enhances _______ of the uterus after parturition.
    • term
    • uterine contractions and distention of the cervix
    • hypothalamus
    • increase uterine contractility
    • * positive feedback
    • involution
  24. Hormones derived from hypothalamic neurons are secreted in the median eminence and delivered to the anterior pituitary through the _______. This yields _______ of the releasing and inhibitory hormones at the target pituitary cells.
    • portal vein
    • a high concentration
  25. Releasing Hormones act on ________ of specific pituitary endocrine cells to stimulate ______ and/or _______ of the pituitary hormones.
    • plasma membrane receptors
    • the exocytosis
    • the synthesis
  26. Releasing hormones are released at the median eminence in _____.
    waves
  27. Cellular mechanisms of action of hypothalamic releasing hormones on anterior pituitary cells
    receptors
    second messengers
    actions
    • almost all GPCR
    • second messengers: Ca++, IP3, cAMP
    • modulate transcription, post-translation modification, exocytosis
  28. Regulatory hormones, target pituitary cells and target hormones
    Thyrotropin‐Releasing Hormone (TRH) -> Thyrotroph -> Thyrotropin (TSH) or ...->  Mammotroph -> Prolactin

    Gonadotropin‐Releasing Hormone (GnRH) -> Gonadotroph -> Luteinizing Hormone (LH) and Follicle‐Stimulating Hormone (FSH)

    Corticotropin‐Releasing Hormone (CRH) -> Corticotroph -> Adrenocorticotropic Hormone (ACTH, Corticotropin)

    Growth Hormone‐Releasing Hormone (GHRH) -> Somatotroph -> Growth Hormone (GH, Somatotropin)

    Growth Hormone‐Inhibiting Hormone (Somatostatin) -> Somatotroph -> Growth Hormone (GH, Somatotropin) or ... -> Thyrotroph -> Thyrotropin (TSH)

    Prolactin‐Inhibiting Factor (PIF, Dopamine) -> Mammotroph -> Prolactin
  29. Action of the pituitary hormones
    • Thyroid‐Stimulating Hormone (TSH): Thyroid hormone secretion and enlargement of thyroid gland
    • Luteinizing Hormone (LH): Ovulation and luteinization (female); testosterone secretion (male)
    • Follicle‐StimulatingHormone (FSH): Ovarian follicle growth, estrogensecretion (female); spermatogenesis (male)
    • Adrenocorticotropic Hormone (ACTH): Hormone secretion and cell growth in adrenal cortex
    • Growth Hormone (GH): Body growth; secretion of IGF‐I
    • Prolactin: Milk secretion
  30. An important mechanism of regulation of pituitary hormone release is _________.
    through negative feedback exerted by the peripheral hormones on both the pituitary and hypothalamus
  31. Growth hormone (GH) is a _____ hormone secreted by the _______ cells of the _____ pituitary.
    GH has a key role in _______. GH also plays an important role in _______.
    GH secretion from the anterior pituitary is regulated by _______ from the hypothalamus.
    • polypeptide
    • somatotroph
    • anterior
    • the stimulation of growth and development of children
    • regulating metabolism, which continues in adults
    • both positive (GH‐RH) and inhibitory (Somatostatin, GH‐IH) factors
  32. In addition to direct peripheral targets, GH also stimulates the secretion of ________, which exerts ______ feedback on GH secretion by ______.
    • somatomedin (IGF, Insulin-like Growth Factor) from liver and other tissues
    • negative
    • inhibiting hypothalamic GHRH secretion and enhancing GH‐IH secretion, which inhibits the secretion of GH at pituitary level
  33. Growth hormone (GH) acts on peripheral tissues directly, but also acts through _____, which stimulate anabolic responses of bone, muscle and other organs to increase _____ and enhance _______.
    • the release of secondary peptide hormones called Somatomedins (also know as insulin‐like growth factors, IGF‐1 and IGF‐2)
    • protein synthesis
    • cell proliferation and growth
  34. The direct effects of GH oppose some of the actions of insulin, since it ________ (thus GH is _______)
    • inhibits glucose uptake and enhances lipolysis
    • diabetogenic
  35. Metabolic and growth targets of GH and Somatomedin (IGF‐1).
    • both induce protein synthesis and epiphysial growth
    • GH: stims lipolysis and decreases insulin sensitivity
    • IGF-1: induces insulin-like activity and has antilipolytic activity
  36. GH overall actions
    • increase metabolism, linear growth, lean body mass, organ size and function
    • decrease adiposity
  37. Role of Growth Hormone, Thyroid Hormones and Androgens/Estrogens in mediating human growth
    • Thyroid hormones dominates during early childhood, results in very high rate of growth, then decreases continuously
    • growth hormone peaks at 2-3, stays high till 16, then decreases
    • sex hormone peaks during puberty, responsible to the 2nd growth peak
  38. Too much growth hormone (GH) during childhood can result in _____.
    Too little GH can result in ______.
    Mental development under both situations are ______.
    • gigantism
    • pituitary dwarfism
    • normal

    * body growth is in proportion
  39. Acromegaly is a syndrome caused by _______, usually from a ______. This causes a variety of changes, including ______, accumulation of excess soft tissue, thickening of skin and _______. Results in _________. Diabetes may also occur. Treatment is by _______.
    • sustained hypersecretion of GH
    • pituitary somatotroph tumor
    • widening of bones
    • hair growth
    • coarser facial features, enlarged hands and feet and overdevelopment of muscles
    • surgery or somatostatin analogs
  40. Prolactin (PRL) is a ______ hormone. It's major effects are ________.
    • polypeptide
    • to stimulate breast development and milk production in women
  41. Prolactin Levels increase during ______, and are further stimulated by ____. Prolactin secretion is also enhanced by ________.
    • pregnancy
    • nursing
    • high estrogen levels acting directly on the mammotrophs of the anterior pituitary
  42. Hypothalamic regulation of PRL secretion is predominantly through _______.
    Less important are _________.
    There is also negative feedback on the hypothalamus by ________.
    • dopamine (PIF), which is an inhibiting hormone
    • the releasing hormones Thyrotropin Releasing Hormone (TRH) and Vasoactive Intestinal Peptide (VIP) * positive
    • prolactin stimulation of dopamine release
  43. Pituitary Intermediate lobe secrets ________, which _________.
    • Melanocyte‐stimulating hormone (MSH)
    • Expand melanophores in fish, amphibians, and reptiles; stimulate melanin synthesis in melanocytes in humans.
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Physiology - Endocrine - HYPOTHALAMUS & PITUITARY GLAND
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Physiology - Endocrine - HYPOTHALAMUS & PITUITARY GLAND
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