Endocrinology Overview Flashcards

1
Q

hypothalamus - releasing hormones

A
  1. thyrotropin releasing hormone (TRH)
  2. growth hormone releasing hormone (GHRH)
  3. gonadotropin releasing hormone (GnRH)
  4. corticotropin releasing hormone (CRH)

*target: stimulate the anterior pituitary to make/release other hormones

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2
Q

hypothalamus - inhibitor hormones

A
  1. dopamine (prolactin-inhibiting factor)
  2. somatostatin (growth hormone-inhibiting factor, GHIH)

*target tissues = anterior pituitary (both) & GI tract (somatostatin only)

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3
Q

anterior pituitary - hormones

A
  1. follicle stimulating hormone (FSH)
  2. luteinizing hormone (LH)
  3. adrenocorticotrophic hormone (ACTH)
  4. thyroid stimulating hormone (thyrotropin, TSH)
  5. prolactin
  6. growth hormone (somatotropin)
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4
Q

posterior pituitary - hormones

A
  1. antidiuretic hormone (ADH, vasopressin)
  2. oxytocin
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5
Q

intermediate pituitary - hormones

A
  1. melanocyte stimulating hormone
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6
Q

thyroid gland - follicular cell hormones

A
  1. thyroxine (T4)
  2. tri-iodothyronine (T3)
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7
Q

thyroid gland - parafollicular cell (C-cell) hormones

A
  1. calcitonin
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8
Q

parathyroid gland - hormones

A
  1. parathyroid hormone (PTH)
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9
Q

adrenal medulla - hormones

A
  1. catecholamines (including epinephrine, norepinephrine)
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10
Q

adrenal cortex - hormones

A
  1. glucocorticoids (including cortisol)
  2. mineralocorticoids (including aldosterone)
  3. androgens
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11
Q

gonads - hormones

A
  1. ovaries: estrogen, progesterone
  2. testes: testosterone
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12
Q

pancreas - hormones

A
  1. insulin (from beta cells)
  2. glucagon (from alpha cells)
  3. somatostatin (from delta cells)
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13
Q

negative feedback loops (general principles)

A

*hormone products INHIBIT further hormone release
*most signaling pathways in the endocrine system utilize negative feedback loops (ex. cortisol, thyroid hormone)

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14
Q

positive feedback loops (general principles)

A

*hormone products STIMULATE further hormone release
*ex. oxytocin hormone during childbirth

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15
Q

secretory patterns of hormones (general principles)

A

different hormones have different secretory patterns; some examples include:
1. release in a pulsatile fashion: e.g. GnRH, LH
2. diurnal variation (influenced by light / sleep-wake cycle): e.g. ACTH, cortisol, GH, TSH, prolactin
3. release in response to specific stimuli (injury, stress, etc): e.g. cortisol, GH
4. changes in secretion over one’s lifetime: e.g. testosterone

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16
Q

dynamic testing - defined

A

*refers to the concept of trying to stimulate or inhibit the release of a certain hormone to see if a person’s body is making too much or too little of that hormone
*not all hormone levels can be checked with a simple blood draw
*ex: the cosyntropin stimulation test tried to stimulate the adrenal gland to produce cortisol

17
Q

endocrine cellular communication - defined

A

*a factor is secreted into a capillary bed and transported to a distant site
*“traditional” hormone secretion

18
Q

paracrine cellular communication - defined

A

*a factor is secreted and acts at a local site, targeting neighboring cells of a different type

19
Q

autocrine cellular communication - defined

A

*a factor is produced by a cell and acts on the same cell, often as a means of regulation

20
Q

endocrine signaling - key concepts

A

*hormones travel through blood, exposing many cells to various hormones, in order to cause effects at a distance from their source glands, BUT hormones only affect cells with the appropriate receptors

21
Q

steroid hormones - defined

A

*derived from cholesterol
*lipophilic & hydrophobic

*membrane permeable; use INTRACELLULAR receptors
*enter cells to create a response: gene transcription
*require binding proteins for blood transport, which:
-increase hormone half-life
-serve as a storage pool
-regulate active hormone availability

22
Q

non-steroid hormones - defined

A
  1. amines: derived from single amino acid (usually tyrosine)
  2. peptides: derived from short chains of amino acids
23
Q

steroids hormones - examples

A
  1. progesterone
  2. estrogen
  3. testosterone
  4. cortisol
  5. aldosterone
  6. thyroid hormone (T3/T4)
  7. vitamin D
24
Q

types of hormone receptors

A
  1. intracellular receptors
  2. cell-surface receptors:
    a. G-protein-couple receptors (GPCRs)
    b. receptor tyrosine kinases
    c. nonreceptor tyrosine kinases
25
intracellular hormone receptors (overview)
*located in nucleus or cytoplasm *used by **lipophilic** hormones that can permeate cell membranes (including ALL steroid hormones) *effect is to **regulate gene transcription**
26
hormones that use intracellular receptors
**ALL steroid hormones:** *progesterone *estrogen *testosterone *cortisol *aldosterone *thyroid hormones (T3/T4) *vitamin D
27
G protein-coupled receptors (GPCRs) that use **cAMP** (overview)
*located on the cell surface *GPCRs have 7 transmembrane domains and signal through G-proteins that activate enzymes (**adenylyl cyclase**) to convert ATP to **cAMP** (second messenger), which activates protein kinase A, whiich increases intracellular calcium
28
hormones that signal via cAMP
*FSH *LH *ACTH *TSH *CRH *hCG *ADH *MSH *PTH *calcitonin *histamine (H2) *GHRH *glucagon *catecholamines
29
G protein-coupled receptors (GPCRs) that use **IP3** (overview)
*GPCRs (alpha-q subunit) activate **phospholipase C** enzyme which produces second messengers **IP3** and DAG which activates protein kinase C
30
hormones that signal via IP3/DAG
*GnRH *oxytocin *ADH/vasopressin *TRH *histamine (H1) *angiotensin II *gastrin
31
receptor tyrosine kinases (RTKs) - overview
*activated by ligand-induced dimerization, leading to auto-phosphorylation of tyrosine residues → signaling cascade via **MAP kinase** pathway
32
hormones that use receptor tyrosine kinases
***insulin** *IGF-1 *FGF *PDGF *EGF *TGF-B
33
nonreceptor tyrosine kinases - overview
*doesn't have it's own tyrosine kinase, so it couples with TK from a JAK protein → phosphorylation and **dimerization** of STAT gene transcription
34
hormones that use nonreceptor tyrosine kinases and JAK/STAT pathway
*G-CSF *erythropoietin *thrombopoietin *prolactin *immunomodulators: IL-2, IL-6, interferons *growth hormone *leptin