Endocrine and Growth: pituitary, pineal, gonads

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VASUpharm14
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Endocrine and Growth: pituitary, pineal, gonads
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2010-11-28 17:11:26
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im too cool
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IBHS final 525 ... dr. n (Endocrine system: Growth) .. it's been a long while, but I figure I can't screw up anymore ... time to put in that extra elbow grease to knock it out of the ballpark.
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  1. context: endocrine system
    Name several endocrine hormones that control growth (6)
    • 1. Growth hormone
    • 2. thyroid hormone
    • 3. insulin
    • 4. parathyroid hormone
    • 5. calcitriol
    • 6. reproductive hormones
  2. T/F
    placenta is an exocrine organ
    false, we wouldn't be having this conversation since the chapter is on endocrine system, but hey, the gonads are pictured outside of the speedo in the illustration.
  3. context: nervous vs endocrine system
    Nervous system
    • 1. release neurotransmitters into synaptic cleft containing specific receptors
    • 2. Relays signals.
    • 3. Regulates specific cells or cell groups (muscles, glands)
    • - Rapid, short-term effects
    • -Cannot regulate long-term processes (growth, reproduction)
  4. context: nervous vs endocrine system
    Endocrine system
    • 1. Release hormones into ECF and bloodstream
    • 2. influence target tissues containing specific receptors.
    • -Slow, long-term effects
    • -can effect entire body
    • -ductless
  5. context: nervous vs endocrine system
    Neuroendocrine
    how the nervous system regulates/influences the endocrine system
  6. context: intercellular signaling
    name the 3 types of signaling
    • 1. endocrine
    • 2. neurocrine
    • 3. neuroendocrine
  7. context: intercellular signaling
    endocrine signaling
    cells that secrete chemical messengers (hormones) into the bloodstream
  8. context: intercellular signaling
    neurocrine
    neurons releasing chemical messengers that enter the bloodstream
  9. context: intercellular signaling
    neuroendocrine
    neuronal action potential results in the release of hormones from endocrine cells
  10. context: endocrine reflexes
    Name 3 components in reflex arcs of the endocrine reflexes
    • aka feedback loops (regulates homeostasis)
    • 1. receptor
    • 2. integration center
    • 3. effector
  11. context: endocrine reflexes- 3 components
    receptor
    sensitive to particular stimuli
  12. context: endocrine reflexes- 3 components
    integration center
    usually CNS. Receives and processes information from receptor and sends out commands
  13. context: endocrine reflexes- 3 components
    effector
    • cell/organ responding to commands (opposes or enhances initial stimuli)
    • -set point changes in living things
    • *most endocrine reflexes are negative feedback loops
  14. context: endocrine reflexes
    Name the 3 types of reflexes
    • 1. Nervous system reflex
    • 2. Endocrine system reflex
    • 3. Neuroendocrine reflex
  15. context: endocrine reflexes- 3 types of reflexes
    nervous system reflex
    withdrawal reflex (ex: pull away from hot pan)
  16. context: endocrine reflexes- 3 types of reflexes
    endocrine system reflex
    increase blood glucose --> insulin (by Beta cells of pancreas) --> lower BG
  17. context: endocrine reflexes- 3 types of reflexes
    neuroendocrine reflex
    neurons of hypothalamus signal endocrine cells of adrenal glands to release EPI --> adequate EPI
  18. context: endocrine reflexes
    Endocrine and Neuroendocrine reflexes are triggered by what 3 stimuli?
    • 1. humoral
    • 2. hormonal
    • 3. neural
  19. context: endocrine reflexes - 3 stimuli for endocrine and neuroendocrine reflexes
    humoral
    change in composition of extracellular fluid
  20. context: endocrine reflexes - 3 stimuli for endocrine and neuroendocrine reflexes
    hormonal
    hormone binding to receptor
  21. context: endocrine reflexes - 3 stimuli for endocrine and neuroendocrine reflexes
    neural
    neurotransmitter present at neuroglandular junction
  22. 5 features of the endocrine system
    • 1. single endocrine gland may produce more than one hormone
    • 2. one hormone may be produced by several endocrine glands
    • 3. a target cell can be influenced by several different hormones
    • 4. a single chemical can be both a hormone and neurotransmitter
    • 5. some organs only produce hormones, other produce hormones and perform other functions too
  23. context: 5 features of the endocrine system
    example for : single endocrine gland may produce more than one hormone
    anterior pituitary produces 7 hormones
  24. context: 5 features of the endocrine system
    example for : one hormone may be produced by several endocrine glands
    ovaries and placenta both produce Estrogen
  25. context: 5 features of the endocrine system
    example for : a target cell can be influenced by several different hormones
    multiple populations of receptors
  26. context: 5 features of the endocrine system
    example for : a single chemical can be both a hormone and neurotransmitter
    NE (in bloodstream and synaptic cleft)
  27. context: 5 features of the endocrine system
    example for : some organs only produce hormones, others produce hormones and perform other functions too
    ovaries produce hormones and release ovum
  28. How are hormones classified?
    by chemical structures
  29. 3 classifications of hormones
    • 1. amino acid derivatives
    • 2. peptide hormones
    • 3. lipid derivatives
  30. context: 3 classifications of hormones
    amino acid derivatives branch out to (2)?
    • 1. derivatives of Tyrosine
    • 2. derivatives of Tryptophan
  31. context: 3 classifications of hormones - amino acid derivatives
    derivatives of Tyrosine branch out to (2)?
    • 1. Thyroid hormones (Thyroxine (Thyroid gland))
    • 2. Catecholamines (Epinephrine (AM), Norepinephrine (AM), Dopamine (H) - END)
    • AM = adrenal medulla
    • H = hypothalamus
  32. context: 3 classifications of hormones - amino acid derivatives
    derivatives of Tryptophan branch out to (1)?
    1. Melatonin (Pineal gland)
  33. context: 3 classifications of hormones
    peptide hormones branch out to (2)?
    • 1. glycoproteins (>200a.a. + carbs/sugars)
    • 2. short polypeptides and small proteins (<200a.a.)
  34. context: 3 classifications of hormones - peptide hormones
    glycoproteins include:
    • 1. pituitary gland - TSH, FSH, LH
    • 2. kidneys - EPO
    • 3. reproductive organs - inhibin
  35. context: 3 classifications of hormones - peptide hormones
    short polypeptides and small proteins include:
    • 1. hypothalamus - ADH, oxytocin, regulatory hormones
    • 2. pituitary gland - ACTH, GH, MSH, PRL
    • 3. heart - ANP, BNP
    • 4. digestive tract - hormones (ch. 24)
    • 5. pancreas - insulin, glucagon
    • 6. parathyroid gland - PTH
    • 7. C cells of thyroid - CT
    • 8. adipose tissue - leptin, resistin
    • 9. lymphatic system - hormones (ch. 22)
  36. context: 3 classifications of hormones
    lipid derivatives branch out to (2)?
    • 1. eicosanoids - lipid derivatives of arachidonic acid
    • 2. steroid hormones - structurally similar to cholesterol
  37. context: 3 classifications of hormones - lipid derivatives
    eicosanoids include (4):
    • 1. leukotrienes
    • 2. prostaglandins
    • 3. thromboxanes
    • 4. prostacyclins
  38. context: 3 classifications of hormones - lipid derivatives
    steroid hormones include:
    • 1. gonads - androgens, estrogens (ex: estradiol), progestins
    • 2. adrenal cortex - mineralocorticoids, glucocorticoids, androgens
    • 3. kidneys - calcitriol
  39. context: 3 classification of hormones
    2 solubility types
    • 1. hydrophilic - cell membrane receptor
    • -ex- GPCR, ion channel-linked, enzyme-linked (phosphorylases)
    • 2. lipophilic - intracellular receptors
    • -ex- steroids
  40. context: hypothalamus and pituitary gland: basic A&P
    Hypothalamic- Pituitary Axis is made of 2 parts
    • 1. hypothalamus
    • 2. pituitary gland (aka hypophysis)
    • *connected: by infundibulum of hypothalamus
  41. context: hypothalamus and pituitary gland: basic A&P
    Pituitary gland is made of 2 parts
    • 1. anterior pituitary (adenohypophysis): consists of glandular tissue - produces 7 hormones
    • 2. posterior pituitary (neurohypophysis): consists of neural tissue - produces 2 hormones
  42. context: hypothalamus and pituitary gland: basic A&P
    what types of hormones are hypothalamic pituitary axis hormones?
    peptide hormones
  43. context: hypothalamus and pituitary gland: basic A&P
    how are hypothalamic pituitary axis hormones released?
    • usually released in pulsatile fashion
    • - frequency of pulses and amount of hormone released influence response of target tissue
  44. Portal system
    connects 2 capillary beds
  45. pathway of hypophyseal portal system
    artery --> hypothalamic capillary bed --> portal vein --> anterior pituitary capillary bed --> vein
  46. context: hypophyseal portal system
    how do larger molecules (ex: hormones) diffuse from the portal capillaries into the vasculature?
    portal capillaries are fenestrated (window)
  47. what is the highest level of endocrine control?
    hypothalamus
  48. context: hypothalamus
    3 ways for neurons in hypothalamus integrate the nervous and endocrine systems
    • 1. release regulatory hormones
    • 2. act as endocrine organ
    • 3. exert direct neural control over endocrine cells
  49. context: hypothalamus - 3 ways of integration
    release regulatory hormones
    hypothalamic regulatory hormones regulate secretory activity of endocrine cells in the anterior pituitary
  50. context: hypothalamus - 3 ways of integration
    act as an endocrine organ
    hypothalamic nuclei synthesizes hormones and releases into systemic circulation (posterior pituitary)
  51. context: hypothalamus - 3 ways of integration
    exert direct neural control over endocrine cells
    hypothalamic nuclei directly innervate adrenal medulla and regulate hormone secretion
  52. 3 types of neurons in the hypothalamus
    • 1. median eminence
    • 2. supraoptic and paraventricular
    • 3. direct
  53. context: 3 hypothalamic nuclei
    median eminance (neurocrine)
    • synthesis, package, and transport regulatory hormones
    • pathway: released in ECF --> capillary bed --> hypophyseal portal circulation --> capillary bed of anterior pituitary
    • - the hypothalamic regulatory hormone cause the endocrine cells of anterior pituitary to release a hormone into the system circulation
  54. context: 3 hypothalamic nuclei
    supraoptic and paraventricular nuclei (neurocrine)
    • extend into the posterior pituitary and release hormones into ECF
    • pathway: hormone enters capillaries --> system circulation
  55. context: 3 hypothalamic nuclei
    direct (neuroendocrine)
    • directly regulate endocrine cells of the adrenal medulla to release EPI and NE.
    • pathway: increase in sympathetic output (action potentials) --> hormones (NE and EPI) released by adrenal medulla
    • -sympathetic division of ANS.
  56. 2 types of hypothalamic regulatory hormones
    • 1. releasing hormones
    • 2. inhibiting hormones
  57. context: 2 hypothalamic regulatory hormones
    releasing hormones (RH)
    stimulates the synthesis and secretion/release of hormone from anterior pituitary (ex: GH-RH)

    -not every releasing hormone has an opposing inhibitory hormone
  58. context: 2 hypothalamic regulatory hormones
    inhibiting hormones (IH)
    prevents synthesis and secretion of hormone from anterior pituitary (ex: GH-IH)

    -not every releasing hormone has an opposing inhibitory hormone
  59. growth hormone (GH)
    • aka: somatotropin
    • Anterior pituitary
    • stimulates cell growth/division by increasing protein synthesis. expecially skeletal muscle and cartilage
  60. 2 ways to regulate GH release
    • 1. growth hormone-release hormone (GH-RH)
    • aka: somatocrinin
    • 2. growth hormone-inhibiting hormone (GH-IH)
    • aka: somatostatin
    • - both 1 and 2 released from hypothalamic nuclei
    • -results in the release or inhibition of GH from somatotrophs in the anterior pituitary (1 of 7 endocrine cell types)
  61. 2 types of effects of GH
    • 1. direct
    • 2. indirect
  62. context: 2 types of effects of GH
    direct
    • GH doing the work
    • -important when glucose levels are normal
    • a) muscle: inc. a.a. uptake and protein synthesis and inc. myoblast differentiation and proliferation
    • b) adipose: inc. lipolysis (cells use F.A. for energy)
    • c) liver: inc. IGF, inc. glycogenolysis
    • *IGF = insulin-like growth factor
    • aka: somatomedin
    • -produced by liver in response to GH ("hormone 2")
  63. context: 2 types of effects of GH
    indirect
    • IGF doing the work
    • -important when glucose levels are high (post-feed/having a meal)
    • a) muscle: uptake of glucose and a.a.; inc. protein synthesis
    • b) chondrocyte stimulation: linear bone growth
  64. context: regulation of growth hormone secretion
    3 ways of negative feedback
    • 1. GH-RH inhibits its own release from the hypothalamus
    • 2. IGF inhibits release of GH from anterior pituitary
    • 3. GH and IGF stimulates production of Growth Hormone-Inhibiting Hormone (GH-IH) from hypothalamus - decreased release of GH from anterior pituitary
    • (+ on the left tops, is turning "on" an inhibitor)
  65. 3 growth hormone disorders (clinical interest)
    • 1. dwarfism
    • 2. gigantism
    • 3. acromegaly
  66. context: 3 growth hormone disorders
    dwarfism
    • pituitary; proportionally smaller (<4'10")
    • Hyposecretion of GH in childhood
    • treatment: hormone replacement
  67. context: 3 growth hormone disorders
    gigantism
    • (>7'6" 310 lbs.)
    • Hypersecretion of GH in childhood
    • treatment: surgery if pituitary tumor (can mess with other hormones in there)
    • Rx: Somavert; GH antagonist - not very successful
  68. context: 3 growth hormone disorders
    acromegaly
    • more common than gigantism
    • Hypersecretion of GH in adults
    • cartilage and small bones respond
    • enlargement of jaw/skull, extremities
    • treatment: surgery if pituitary tumor
    • Rx: Somavert; GH antagonist - more successful here
  69. 9 peptide hormones of the pituitary gland/hypothalamus
    • 1. growth hormone (GH)
    • 2. thyroid stimulating hormone (TSH)
    • 3. adrenocorticotropic hormone (ACTH)
    • 4. prolactin (PRL)
    • 5. follicle stimulating hormone (FSH)
    • 6. luteinizing hormone (LH)
    • 7. melanocyte stimulating hormone (MSH)
    • ----
    • 8. antidiuretic hormone (ADH) - vasopressin
    • 9. oxytocin
  70. context: 9 peptide hormones of pituitary/hypothalamus
    thyroid stimulating hormone (TSH)
    • Hypothalamic nuclei: release thyroid releasing hormone (TRH) which stimulates the anterior pituitary
    • anterior pituitary: thyrotrophs release thyroid stimulating hormone (TSH)
    • function: target: follicle cells of thyroid gland
    • -TSH regulates all aspects of thyroid hormone synthesis and release of hormone 2 (T3 (more of) and T4)
    • Negative feedback: T3 and T4 inhibit further release of TSH from thyrotrophs and inhibit TSH release from hypothalamus
    • *no inhibitory thyroid hormone
  71. context: 9 peptide hormones of pituitary/hypothalamus
    adrenocorticotropic hormone (ACTH)
    • Hypothalamic nuclei: release of corticotropin releasing hormone (CRH) which stimulates the anterior pituitary
    • anterior pituitary: corticotrophs release adrenocorticotropic hormone (ACTH)
    • function: target: zona fasciculata of adrenal cortex
    • -release of hormone 2 (corticosteroids- cortisol, glucocorticoids)
    • Negative feedback: glucocorticoids inhibit further release of ACTH from corticotrophs and CRH release from hypothalamus
  72. context: 9 peptide hormones of pituitary/hypothalamus
    prolactin (PRL)
    • Hypothalamic nuclei: release of
    • 1. prolactin releasing factors (PRF)
    • 2. prolactin inhibiting hormone (PIH) - ex. Dopamine
    • - inhibits prolactin release
    • anterior pituitary: mammotrophs release prolactin
    • function: target:
    • 1. females - mammary gland development and milk production (not ejection)
    • 2. males - regulates androgen production from testes
    • Negative feedback: prolactin inhibits its own release from mammotrophs and release PRF from the hypothalamus. prolactin also increases release of PIH from hypothalamus.
  73. context: 9 peptide hormones of pituitary/hypothalamus
    follicle stimulating hormone (FSH) and luteinizing hormone (LH)
    • Hypothalamic nuclei: release gonadotropin releasing hormone (GnRH)
    • anterior pituitary: gonadotrophs release
    • 1. follicle stimulating hormone (FSH)
    • 2. luteinizing hormmone (LH)
    • function: target: gonads
    • 1. testes- release androgens
    • 2. ovaries- promotes follicle development and releases Estrogens, Progestins
    • Negative feedback: sex hormones inhibit further release of FSH and LH from gonadotrophs and GnRH release from hypothalamus
  74. context: 9 peptide hormones of pituitary/hypothalamus
    melanonocyte stimulating hormone (MSH)
    • Hypothalamic nuclei: nothing (?)
    • anterior pituitary: MSH only produced during
    • 1. fetal development
    • 2. pregnancy
    • 3. very young children
    • 4. disease states
    • function: target: melanocytes in the skin - melanin production
    • *MSH production in adult humans usually occur locally (skin) - normally not produced by the anterior pituitary
  75. context: 9 peptide hormones of pituitary/hypothalamus
    antidiuretic hormone (ADH)
    • aka vasopressin
    • Hypothalamic nuclei (supraoptic nuclei): synthasize antidiuretic hormone (ADH)
    • posterior pituitary: releases antidiuretic hormone (ADH)
    • function: regulates water and electrolyte balance by decreasing urination; inc. in ADH results in H2O retention in kidney (more aquaporins in collecting duct - keep more water)
    • Stimuli for ADH secretion:
    • 1. Increased plasma osmolarity - detected by osmoreceptors (supraoptic nuclei) in hypothalamus
    • 2. Decreased plasma volume - detected by baroreceptors in aorta, carotid artery
    • Inhibiting ADH secretion:
    • 1. alcohol inhibits ADH causing inc. pee
  76. context: 9 peptide hormones of pituitary/hypothalamus
    oxytocin
    • Hypothalamic nuclei (paraventricular nuclei): synthesize and release oxytocin
    • posterior pituitary: releases oxytocin
    • functions: in reflex loops that are positive feedback loops
    • 1. uterine contractions - stimulates smooth muscle of uterus - may be trigger for labor (released also by uterus and fetus)
    • Rx- Pitocin - labor induction, placental delivery
    • 2. milk ejection - sensory endings in breast stimulated by suckling = oxytocin released into circulation from posterior pituitary --> contraction of myoepithelial cells in breast alveoli = milk ejected into breast ducts = happy baby
    • -stimulates prolactin secretion (inc. milk production)
  77. Male fertility and hormones
    • Hypothlamic nuclei: release gonadotropin releasing hormone (GnRH) - consistant, pulsatile release at puberty
    • anterior pituitary: gonadotrophs release
    • 1. follicle stimulating hormone (FSH)
    • 2. luteinizing hormone (LH)
    • function: target: gonads
    • 1. FSH - stimulates spermatogenesis in sertoli cells (testosterone needed too)
    • 2. LH - inc. testosterone production in Leydig cells
    • Negative feedback:
    • 1. Sertoli cells produce inhibin to dec. FSH (and perhaps GnRH) secretion
    • 2. Testosterone inhibits GnRH release
    • *know seminiferous tubule (not shown)
  78. Female fertility and hormones
    • Hypothalamic nuclei: release gonadotropin releaseing hormone (GnRH) - cyclical/pulsatile release at puberty
    • anterior pituitary: gonadotrophs release
    • 1. follicle stimulating hormone (FSH)
    • 2. luteinizing hormone (LH)
    • function: target: gonads
    • 1. FSH - follicale stimulation and egg maturation by stimulating Estrogen which
    • a) proliferation of endometrium
    • b) thins cervical mucus
    • c) inhibits GnRH
    • 2. LH - ovulation stimulation by stimulating Progesterone (and some Estrogen) which
    • a) differentiation/maintenance of endometrium
    • b) thickens cervical mucus
    • c) inhibits GnRH
    • Negative feedback: inc. Estrogen and Progestorone (with some Estrogen) inhibits GnRH and inhibin from mature ovum causes dec. FSH
  79. Precocious Puberty (clinical interest)
    • Puberty Precocious puberty
    • girls: 10 years < 7 years
    • boys: 12 years < 9 years
    • symptoms:
    • only females:
    • 1. breast development
    • 2. menstruation
    • only males:
    • 1. enlargement of genitalia
    • 2. deeper voice
    • both:
    • 1. acne
    • 2. body hair
    • 3. growth spurt
    • results: self esteem issues, teasing by peers, loss of childhood/innocence, emotional trauma, aggressiveness, age-inappropriate sex drive, breast cancer, growth spurt --> short stature (androgens cause closure of epiphyseal plate)
    • Etiology: in the endocrine system. Usually not ovarian or testicular dysfunction. Hypothalamus triggers pituitary to release FSH, LH etc. --> puberty
    • could it be brain tumor? CNS infection? Head trauma
    • treatment: surgery, antibiotics, LH receptor antagonist
  80. context: Pineal gland
    pinealocytes
    synthesize melatonin from tryptophan
  81. context: Pineal gland
    process of melatonin production
    • collaterals from visual pathway (suprachiasmatic nucleus) enter pineal gland and influence melatonin production
    • -lowest during daylight
  82. context: Pineal gland
    3 functions of melatonin
    • 1. inhibits reproductive functions
    • 2. free radical scavenger
    • 3. establishes circadian rhythms
  83. context: Pineal gland - 3 functions of melatonin
    inhibits reproductive functions
    dec. sperm and oocyte (egg) maturation (via dec. GnRH) - melatonin levels decline at puberty (inc. GnRH)
  84. context: Pineal gland - 3 functions of melatonin
    free radical scavengers
    acts as antioxidant
  85. context: Pineal gland - 3 functions of melatonin
    establishes circadian rhythms
    • sleep/wake cycles
    • - low sunlight in winter results in higher melatonin levels and may contribute to seasonal depression (melatonin supplements may help with insomnia and jet lag)

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