Introduction to Endocrine Physiology Flashcards

1
Q
  • What are the mechanisms of cellular communication?
A
  • Autocrine
  • Paracrine
  • Endocrine
  • Neuroendocrine
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2
Q
  • In addition to hormones secreted by classic endocrine glands, there are:
A
  • Hormones synthesized by endocrine cells w/ organs whose PRIMARY function is not endocrine (Heart, Liver, Kidney, GI Tract, Adipose Tissue)
  • Hormones modified by peripheral conversion (Angiotensin II, Vitamin D)
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3
Q
  • What hormones does the hypothalamus secrete?
A
  • TRH
  • CRH
  • GHRH
  • GnRH
  • Somatostatin
  • Dopamine
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4
Q
  • What hormones does the anterior pituitary secrete?
A
  • TSH
  • FSH
  • LH
  • ACTH
  • MSH
  • GH
  • Prolactin
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5
Q
  • What hormones does the posterior pituitary secrete?
A
  • ADH
  • Oxytocin
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6
Q
  • What hormones does the thyroid secrete?
A
  • T3,T4
  • Calcitonin
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7
Q
  • What hormones does the parathyroid gland secrete?
A
  • PTH
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8
Q
  • What hormones does the pancreas secrete?
A
  • Insulin
  • Glucagon
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9
Q
  • What hormones does the adrenal medulla secrete?
A
  • NE
  • Epi
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10
Q
  • What hormones does the kidney secrete?
A
  • Renin
  • 1,25-Dihydroxycholecalciferol (Calcitriol)
  • EPO
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11
Q
  • What hormones does the adrenal cortex secrete?
A
  • Cortisol
  • Aldosterone
  • Adrenal androgens
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12
Q
  • What hormones do the testes secrete?
A
  • Testosterone
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13
Q
  • What hormones do the ovaries secrete?
A
  • Estradiol
  • Progesterone
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14
Q
  • What hormones does the corpus luteum secrete?
A
  • Estradiol
  • Progesterone
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15
Q
  • What hormones does the placenta secrete?
A
  • HCG: Human chorionic gonadotropin
  • hPL: Human placental lactogen
  • Progesterone
  • Estradiol
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16
Q
  • What are the three general classes of hormones?
A
  • Proteins and peptides (stored in secretory vesicles until used)
    • AA < 100 length are peptides
    • AA > 100 length are proteins
    • Water soluble
  • Amines
    • Tyrosine derived
  • Steroids
    • Not stored
    • Made from cholesterol
    • Lipid-soluble
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17
Q
  • How are protein/peptide hormones synthesized?
  • What are the stimuli for exocytosis?
A
  • Made as preprohormone (not active)
  • Signal peptide removed in ER to make PROHORMONE
  • Packed into vesicles in Golgi
  • Cleaved by proteolytic enzymes and generated to active form
  • Stimuli for exocytosis:
    • ​Increase in intracellular Ca2+ caused by depolarization
    • Activation of GPCR (increase in cAMP and activation of PKA)
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18
Q
  • What are the steroid hormones?
  • Where are they made?
  • How are they modified?
A
  • Hormones:
    • Cortisol
    • Aldosterone
    • Estradiol/Progesterone
    • Testosterone
    • 1,25-dihydroxycalciferol
  • Synthesized in:
    • Adrenal cortex
    • Gonads
    • Corpus Luteum
  • Modification:
    • Removal of side chains
    • Addition of side chains
    • Hydroxylation of steroid nucleus
    • Aromazation of steroid nucleus
19
Q
  • What are the two sources of cholesterol?
A
  • 80% taken up via receptor mediated endocytosis of LDL
  • De novo synthesis from acetyl CoA
20
Q
  • What are the genomic actions of steroid hormones?
A
  • Modulate gene transcription by interaction w/ intracellular nuclear receptors
21
Q
  • What are the nongenomic actions of steroid hormones?
A
  • Specific-receptor mediated actions or direct-steroid membane interactions
22
Q
  • Amine hormones are derived from what amino acid?
  • What are the two groups of amine hormones and where are they synthesized?
  • Which has a longer half life?
  • Which category has a faster clearance rate?
A
  • Tyrosine
  • Catecholamines
    • Made in cytosol and secretory granules
    • Act thru cell-membrane associated receptors
  • Thyroid hormones
    • Made by thyroid
    • Stored within follicles
    • Cross cell membrane and act thru nuclear receptors
  • Thyroids have longest half life
  • Catecholamines have faster clearance rate
23
Q
  • How are the secretions of hormones turned on and off?
A
  • Neural mechanism
    • Neuronal input to an endocrine cell increases or decreases hormonal secretion
  • Feedback mechanism
    • More common
    • Some element of the physiological response feeds back to act directly or indirectly on endocrine gland to increase or decrease secretion rate
    • Negative feedback mech predominates
24
Q
  • Positive feedback mechanisms:
    • ​Characteristics
    • Examples
A
  • Rare
  • Self-augmenting
  • Leads to explosive event
  • Rarely used to maintain homeostatic functions
  • Examples:
    • Menstrual cycle (estrogen stimulates FSH and LH, further increasing estrogen level)
    • Delivery of baby (oxytocin)
25
Q
  • Negative feedback mechanisms:
    • ​Characteristics
    • Types
A
  • Underlies homeostatic regulation of organ systems
  • Types:
    • Long loops
    • Short-Loop feedback
    • Ultra short loop
26
Q
  • Long loop feedback
A

Hormone released from third tier (peripheral endocrine gland) feeds back to the 1st tier

27
Q
  • Short loop feedback
A
  • Hormone secreted from the 2nd tier feeds back and inhibits 1st tier
28
Q
  • Ultra short loop feedback
A
  • Gland inhibits its own secretion
29
Q
  • What are the three endocrine axes?
A
  • HPA (hypothalamic-pituitary adrenal gland axis)
  • HPT (hypothalamus-pituitary-thyroid gland axis)
  • HPG (hypothalamus-pituitary-gonads axis)
30
Q
  • Physiological response driven negative feedback loops
A
  • Response driven feedback
  • Secretion of a hormone is stimulated or inhibited by a change in level of extracellular signal
  • EX:
    • Insulin regulates BGL; BG concentration turns on or off insulin secretion
      • Turned on in high blood glucose
      • Decreases in low blood glucose levels
31
Q
  • Two major inputs that control first tier of the endocrine axes (hypothalamus)
A
  • Pineal gland
    • Melatonin
  • SCN
    • Circadian rhythms on secretion of hypothalamic releasing hormones and endocrine axes
32
Q
  • Identify sensitivity of a hormone
  • How can responsiveness of a hormone be changed?
A
  • Sensitivity-hormone concentration that produces 50% of maximal response
  • Changing the number of receptors or receptor affinity for the hormone
33
Q
  • Up-regulation
A
  • Increase receptor number or sensitivity of target tissue when hormone levels are low
    • Increase in synthesis in new receptors
    • Decrease in degradation of existing receptors
    • Activating receptors
34
Q
  • Down-regulation
A
  • Reducing receptor number or sensitivity of target tissue when hormone levels are high or for an extended period of time
  • Decrease in synthesis of new receptos
  • Increase in degredation of existing receptors
  • Inactivating/desensitizing receptors
35
Q
  • Adenylyl cyclase MOA
    • 1st messenger
    • Primary effector
    • 2nd messenger
    • Secondary effector
A
  • 1st messenger-hormones (ACTH, LH, FSH, TH, Glucagon)
  • Primary effector: Adenylyl Cyclase
  • 2nd messenger: cAMP
  • Secondary effector: PKA
36
Q
  • Phospholipase C Mechanism of Action
    • 1st messenger
    • primary effector
    • 2nd messenger
    • secondary effector
A
  • 1st messenger: hormone (GnRH, TRH, Oxytocin)
  • Primary effector: Phospholipase C
  • 2nd messenger: IP3/DAG/Ca2+
  • Secondary effector: PKC or calmodulin
37
Q
  • Guanylyl Cyclase MOA ​
    • ​1st messenger
    • Primary effector
    • 2nd messenger
    • Secondary effector
A
  • 1st messenger
    • Hormones
      • ANP-thru receptor
      • NO-can pass thru cytosol
  • Primary effector
    • Guanylate cyclase
  • 2nd messenger
    • cGMP
  • Secondary effector
    • PKG
38
Q
  • Steroid hormones (Thyroid hormone, glucocorticoids, aldosterone, estrogen, testosterone, etc.) MOA
A
  • Act thru cytosolic/nuclear receptors
  • Receptors are monomeric proteins w/ 6 domains (A-f)
    • E domain: steroid binding domain-closer to C terminus
    • C domain: 2 zinc fingers, binds DNA, highly conserved-closer to N terminus
    • Hormone receptor complex works as a transcription factor that regulates the rate of transcription of a gene
    • Nature of the new protein is SPECIFIC to the hormone
39
Q
  • What are the two categories of tyrosine kinases?
A
  • Receptor tyrosine kinases
  • Tyrosine kinase associated receptors
40
Q
  • Receptor tyrosine kinases
A
  • Have intrinsic tyrosine kinase activity within receptor
  • When activated, phosphorylates itself and other proteins
  • EX: Nerve growth factor w/ epidermal growth factor receptors or insulin w/ insulin like growth receptor
41
Q
  • Tyrosine kinase associated receptors
A
  • Associate non-covalently to proteins that have tyrosine kinase activity
  • EX: JAK
42
Q

GHRH is a _ that after receptor activation, stimulates intracellular _ production

A
  • GPCR (Gs), cAMP
43
Q
  • Mass lesions
A
  • Enlargement of the endocrine organ due to an underlying neoplasia or hyperplasia