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Endo/Repro > Intro to Endocrine > Flashcards

Intro to Endocrine Flashcards

1
Q

Hormones

A

secreted by endocrine glands and tissues

  • effective at LOW [ ]
  • autocrine, endocrine, and paracrine effects
  • bind carrier proteins in serum
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2
Q

3 types of hormones

A
  1. peptide-protein
  2. Lipid
  3. Nonpeptide AA based
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3
Q

Bind to receptors on target cells

A

Free Hormone and Free Receptor form Hormone-Receptor complex

  • reversible binding, saturable
  • varying levels of specificity
  • activates secondary messengers or transcription
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4
Q

Infundibulum

A

stalk that connects pituitary to brain

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5
Q

Posterior pituitary

A

extension of neural tissue –> controlled by hypothalamus and its hormones (ADH and oxytocin)
- hormones immediately enter circulation –> FAST response

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6
Q

Anterior pituitary

A

true endocrine gland of epithelial origin –> regulated by hormone secretion from hypothalamus (hypothalamo-pituitary endocrine axis)

  • hypothalamic control is either releasing or inhibiting
  • portal system
  • may involve 3rd endocrine gland –> SLOW response
  • hormone may act as (-) feedback regulator
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7
Q

Negative feedback regulation

A

most common mechanism

- limits amount of hormone release -> prevents snow-balling

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8
Q

Positive feedback regulation

A

Rare, reinforces snow-ball effect

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9
Q

Protein/peptide hormone synthesis

A

preprohormone synthesized and cleaved into prohormone in RER –> golgi further cleaves it into mature hormone –> packaged into secretory granules
- water soluble -> can be transported by carrier proteins but not required

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10
Q

Steroid hormone synthesis

A

derived from cholesterol -> converted to final product by enzymatic reaction (mito and smooth ER)

  • produced and secreted without storage -> traverse cell membranes down [ ]
  • not water soluble -> 99.9% bound to carrier proteins
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11
Q

Eicosanoids

A

biologically active lipid mediators

  • signal through GPCR
  • occur at low levels in tissues and are drugable targets
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12
Q

Hormones derived from arachdonic acid

A
  1. COX-1,2 –> prostaglandins
  2. 5-LO –> luekotrienes
  3. 12LO –> 12-HETE
  4. 15-LO –> 15-HETE
  5. Cyt P450 –> HETEs and epoxides
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13
Q

Amines

A

Catecholamines (tyrosine derived)
Thyroid Hormones -> act like steroids and bind receptors which also belong to nuclear receptor family
- production controlled by enzymes and iodine availability
Tryptophan hormones –> serotonin, melatonin

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14
Q

Down-regulating hormone signaling

A
  1. decreasing receptor #

2. increasing degradation of hormone cells

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15
Q

Up-regulating hormone signaling

A
  1. increase receptor #

2. decreasing intracellular degradation of hormone

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16
Q

Protein/peptide hormones

A

bind to receptors of target cell-membrane (tyrosine kinase)

- secondary messengers (guanosine triphosphate, AC -> cAMP, PLC -> DAG & IP3 , Ca2+)

17
Q

Most protein hormone receptors are coupled to Gsalpha

A

Gsalpha -> AC -> increase cAMP -> PKA -> phosphorylation

18
Q

Steroid signaling (nuclear receptor superfamily)

A 
Estrogens
Progesterones
Androgens
Glucocorticoids
Mineralocorticoids
19
Q

Unliganded RXR heterodimers with hormone

A

receptor complexes to activate transcription (transcription factor)

  • thyroid hormones
  • Vitamin D
  • Eicosanoids, PGs, LTKs, FFAs
  • FXR - bile acid receptor
  • RAR - all trans retinoic acid
20
Q

Ligand RXR homodimers

A

require hormone binding for transcriptional activation

  • co-repressor is released with T3 binding
  • co-activator binds to hormone/receptor complex
  • transcription is modulated
21
Q

Steroid signaling

A
  1. Free hormone dissociates from carrier protein and enters cell
  2. Hormone binds cytoplasmic receptor and translocates to nucleus
  3. Dimers form and sit on steroid response element
  4. Transcription
  5. Translation
  6. Hormone cellular response
22
Q

Hormone Fates

A

Liver/Kidney metabolic degradation of circulating hormone

- carrier proteins extend half-life of hormones

23
Q

Pulsatile secretion

A

hypothalamic and pituitary hormones are secreted in pulsatile pattern to prevent desensitization of downstream receptors

24
Q

Continuous administration of hormones?

A

down regulates the hormone receptors and as a result the reduced hormone signaling ensues

25
Q

Multiple Hormones?

A

can be additive, synergistic, permissive, antagonistic

Endo/Repro (34 decks)

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