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Endo/Repro I Exam 1 > Lecture 1: Intro to Endocrinology > Flashcards

Lecture 1: Intro to Endocrinology Flashcards

1
Q

Which hormones arise from the Hypothalamus; what’s their main action?

A
  • TRH: stimulates secretion of TSH and prolactin
  • CRH: stimulates secretion of ACTH
  • GnRH: stimulates secretion of LH and FSH
  • Somatostatin: inhibits secretion of GH
  • Dopamine: inhibits secretion of prolactine
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2
Q

Which hormones arise from the Anterior Pituitary gland; main function of each?

A
  • TSH: stimulates synthesis/secretion of thyroid hormones
  • FSH: sperm maturation (males)/follicular dev. and estrogen synthesis (females)
  • LH: testosterone synthesis (males)/ovulation, formation of corpus luteum, estrogen, and progesterone synthesis in ovaries (females)
  • ACTH: synthesis and secretion of cortisol, androgens, aldoesterone
  • MSH: melanin synthesis
  • Growth Hormone: protein synthesis and overall growth
  • Prolactin: milk production and secretion in breast
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3
Q

Which hormones arise from the Posterior Pituitary; function of each?

A
  • ADH: water reabsorption in principle cells of collecting ducts and constriction of arterioles
  • Oxytocin: milk ejection from breasts and uterine contraction
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4
Q

Which hormones arise from the Thyroid gland?

A
  • T3, T4: skeletal growth; O2 consumption; heat prod.; protein, fat, and CHO utilization; perinatal maturation of CNS
  • Calcitonin: decreases serum [Ca2+]
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5
Q

How are protein and peptide hormones usually synthesized and describe their route to becoming active?

A
  • Synthesized as preprohormones (not biologically active)
  • Signal peptide removed in the ER to produce prohormone
  • Once they are packed into vesicles they are cleaved by proteolytic enzymes generating the active form
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6
Q

What can act as a stimulus for exocytosis of peptide/protein hormones from secretory vesicles?

A
  • Increased intracellular Ca2+ caused by membrane depolarization
  • Activation of GPCR’s, followed by increased cAMP and activation of PKA
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7
Q

What are the steroid hormones?

A
  • Cortisol
  • Aldosterone
  • Estradiol
  • Progesterone
  • Testosterone
  • 1,25-dihydroxycholecalciferol
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8
Q

The steroid hormones are synthesized and secreted from what 3 structures?

A
  • Adrenal cortex
  • Gonads
  • Corpus luteum
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9
Q

What are the 2 sources of cholesterol for the synthesis of steroid hormones?

A
  • LDL particles taken up through receptor-mediated endocytosis
  • De novo synthesis for acetyl CoA
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10
Q

What are the genomic vs. nongenomic actions of steroid hormones?

A

Genomic (common theory): modulate gene transcription by interaction w/ intracellular, nuclear receptors

Nongenomic: rapid steroid actions. Specific-receptor-mediated actions or direct steroid-membrane interactions

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11
Q

Where are amine hormones dervied from and what are the 2 classification groups; how does each group act on its receptor?

A
  • Derived from tyrosine
    1) Catecholamines - act through cell-membrane associated receptors
    2) Thyroid hormones - cross cell membrane and act thru nuclear receptors
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12
Q

What hormone comes from the Parathyroid gland and what is its function?

A

PTH: increases serum [Ca2+]

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13
Q

What hormones are secreted by the Adrenal Cortex and what are their functions?

A
  • Cortisol: stimulates gluconeogenesis; inhibits inflammatory response; suppresses immune response; enhances vascular responsiveness to catecholamines
  • Aldosterone: increases renal Na+ reabsorption, K+ secretion, and H+ secretion
  • DHEA: stimulates spermatogenesis; stimulates male secondary sex characteristics
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14
Q

Which hormones are secreted from the Ovaries and Corpus Luteum; what are their actions?

A
  • Estradiol: stimulates growth/development of female repro. system. follicular phase of menstrual cycle, dev. of breasts, prolactin secretion; maintains pregnancy
  • Progesterone: stimulates luteal phase of menstrual cycle; maintains pregnancy
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15
Q

What hormones are secreted from the placenta and what are their actions?

A
  • HCG: stimulates estrogen and progesterone synthesis in corpus luteum of early pregnancy
  • hPL: has growth hormone-like and prolactin-like actions during pregnancy
  • Estriol: same actions of estradiol
  • Progesterone
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16
Q

Which hormones are secreted by the kidney and their actions?

A
  • Renin: catalyzes conversion of angiotensinogen to angiotensin I
  • 1,25-dihydroxycholecalciferol: increases intestinal absorption of Ca2+; bone mineralization
17
Q

How can the secretion of hormones be turned on and off?

A

1) Neural mechanism
2) Negative feedback: most common
3) Positive feedback: rare; leads to an explosive event (i.e., menstrual cycle, delivery of fetus)

18
Q

What is long-loop feedback?

A

Hormone released from the 3rd tier (peripheral endocrine gland) feeds back all the way to the 1st tier (hypothalamus) and 2nd tier (pituitary)

19
Q

What is short-loop feedback?

A

Hormone secreted from the 2nd tier feeds back to the 1st tier

20
Q

What is ultra short-loop feedback?

A

Glands inhibits its own secretion

21
Q

What are the 3 endocrine axes?

A

1) HPA = Hypothalamus - Pituitary - Adrenal gland
2) HPT = Hypothalamus - Pituitary - Thyroid gland
3) HPG = Hypothalamus - Pituitary - Gonads

22
Q

What is response driven feedback; what is an example of this involving insulin?

A
  • Secretion of a hormone is stimulated or inhibited by a change in the level of a specific extracellular signal
  • Insulin regulates blood glucose levels. In turn, blood glucose concentrations turns on or off insulin secretion.
23
Q

How is the first tier of the endocrine axes regulated and what are the major inputs?

A
  • Highly regulated by neural inputs to the hypothalamus
    1) Suprachiasmatic nucleus (SCN): impose a circadian rhythm on the secretion of hypothalamic releasing hormones and endocrine axes
    2) Pineal gland: releases melatonin which feedback to the SCN information about day-night
24
Q

Describe Up-regulation in regards to a low level of circulating hormones

A
  • Increases receptor # or sensitivity of target tissue when hormone levels are low:
  • Increase in the synthesis of new receptors
  • Decrease in the degradation of existing receptors
  • Activating receptors
25
Q

Describe Down-regulation in regards to when circulating levels of hormones are high.

A
  • Reduce receptor # or sensitivity of the target tissue when hormone levels are high for an extended period of time
  • Decrease in the synthesis of new receptors
  • Increase in the degradation of existing receptors
  • Inactivating/desensitizing receptors
26
Q

What is the 1st messenger, primary effector, 2nd messenger, and secondary effector in the Adenylyl cyclase mechanism?

A

1st messenger: hormones (ACTH, LH, FSH, TSH, glucagon)

Primary effector: adenylyl cyclase

2nd messenger: cAMP

Secondary effector: PKA

27
Q

What is the 1st messenger, primary effector, 2nd messenger, and secondary effector in the Phospholipase C mechanism?

A

1st messenger: hormones (GnRH, TRH, GHRH, oxytocin)

Primary effector: phospholipase C

2nd messenger: IP3/DAG/Ca2+

Secondary effector: PKC or calmodulin

28
Q

What are hormone examples for the Steroid hormone mechanism, second messenger, act through what, and final result?

A
  • Thyroid hormones, glucocorticoids, aldosterone, estrogen, testosterone, etc.
  • No second messenger
  • Act through cytosolic/nuclear receptors
  • Hormone-receptor complex acts as a transcription factor
29
Q

What is the E domain and C domain of nuclear receptors for steroid binding?

A

E domain: steroid hormone binding domain

C domain: highly conserved, has 2 zinc fingers, responsible for DNA binding

30
Q

What is the 1st messenger, primary effector, 2nd messenger, and secondary effector of the Guanylyl cyclase mechanism?

A

1st messenger: hormones (ANP and NO)

  • ANP acts thru receptor w/ guanylyl cyclase activity
  • NO diffuses to cytosol and activates cytosolic guanylyl cyclase

Primary effector: guanylate cyclase

2nd messenger: cGMP

Secondary effector: PKG

31
Q

What are receptor tyrosine kinases?

A
  • Have intrinsic tyrosine kinase activity within the receptor molecule
  • When activated, the intrinsic tyrosine kinase phosphorylates itself and other proteins
  • Examples: nerve growth factor and epidermal factor receptors. Insulin and insulin-like growth receptors
32
Q

What are Tyrosine kinase-assocated receptors?

A
  • Associated non-covalently to proteins that have tyrosine kinase activity (i.e., JAK)
33
Q

What are mass lesions?

A

Enlargement of the endocrine organ due to an underlying neoplasia or hyperplasia

Endo/Repro I Exam 1 (12 decks)

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