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NE > Intro to Endocrine (Creamer) > Flashcards

Intro to Endocrine (Creamer) Flashcards

1
Q

hormone signaling where the cell releases a hormone that acts on the cell itself or on a similar cell in the same tissue

A

autocrine signaling

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2
Q

hormone signaling where one cell releases a hormone that acts on different cell, typically within the same tissue/organ

A

paracrine

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3
Q

hormone signaling where one cell releases a hormone within the blood stream to a target cell of a different cell/tissue type

A

endocrine signaling

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4
Q

hormone signaling where a neuron releases a hormone into the blood stream to act on a target cell of a different tissue/organ

A

neuroendocrine

(there is also neurocrine where neuron releases a hormone that acts directly on target tissue)

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5
Q

Name the hypothalamus hormones, their classification, and major actions:

A

Hypothalamus

  • thyrotropin-releasing hormone (TRH): peptide, stim secretion of TSH and prolactin
  • corticotropin-releasing hormone (CRH): peptide, stim secretion of ACTH
  • gonadotropin-releasing hormone (GnRH): peptide, stim secretion of LH and FSH
  • somatostatin or somatotropin release-inhibiting hormone (SRIF): peptide, inhibits secretion of growth hormone
  • dopamine or prolactin-inhibiting hormone (PIF): amine, inhibits secretion of prolactin
  • growth hormone-releasing hormone (GHRH): peptide, stim secretion of growth hormone (GH)
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6
Q

Name the anterior pituitary hormones, their classification, and major actions:

A

Anterior pituitary

  • thyroid-stimulating hormone (TSH): peptide, stim synthesis/secretion of thyroid hormones
  • follicule-stimulating hormone (FSH): peptide, stim sperm maturation in Sertoli cells of testes, stim follicular development and estrogen syn in ovaries
  • luteinizing hormone (LH): peptide; stim testosterone syn in Leydig cells of testes, stim ovulation, formation of corpus luteum, estrogen/progesterone syn in ovaries
  • growth hormone (GH): peptide, stim protein syn and overall growth
  • prolactin: peptide, stim milk prod/secretion in breasts
  • adrenocorticotropic hormone (ACTH): peptide, stim syn/secretion of adrenal cortical hormones (cortisol, androgens, aldosterone)
  • melanocyte-stim hormone (MSH): peptide, stim melanin synthesis
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7
Q

Name the posterior pituitary hormones, their classification, and major actions:

A

Posterior pituitary

  • oxytocin: peptide, stim milk ejection from breasts and uterine contractions
  • vasopressin or antidiuretic hormone (ADH): peptide, stim water reabsorption in principal cells of collecting ducts and constriction of arterioles
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8
Q

Name the thyroid hormones, their classification, and major actions:

A

Thyroid

  • triiodothyronine (T3) and L-thyroxine (T4): amines, stims skeletal growth, oxygen consumption, heat prod, protein, fat, and carb utilization, perinatal maturation of CNS
  • calcitonin: peptide, decreases Ca2+ levels
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9
Q

Name the parathyroid hormones, their classification, and major actions:

A

Parathyroid

  • parathyroid hormone (PTH): peptide, increases Ca2+ levels
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10
Q

Name the adrenal cortex hormones, their classification, and major actions:

A

Adrenal cortex

  • cortisol (glucocorticoid): steroid, stim gluconeogenesis, inhibits inflammatory response, suppresses immune response, enhances vascular responsiveness to catecholamines
  • aldosterone (mineralocorticoid): steroid, increases renal Na+ reabsorption, K+ secretion, and H+ secretion
  • dehydroepiadrosterone (DHEA) and androstenedione (adrenal androgens): steroids, actions of testosterone
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11
Q

Name the testes hormones, their classification, and major actions:

A

Testes

  • testosterone: steroid, stim spermatogenesis, stim male secondary sex characteristics
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12
Q

Name the ovaries hormones, their classification, and major actions:

A

Ovaries

(also prod by corpus luteum)

  • estradiol: steroid; stim growth/development of female repro system, follicular phase of menstrual cycle, development of breasts, prolactin secretion, maintains pregnancy
  • progesterone: steroid; stim luteal phase of menstrual cycle, maintains pregnancy
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13
Q

Name the placenta hormones, their classification, and major actions:

A

Placenta

  • human chorionic gonadotropin (HCG): peptide, stim estrogen/progesterone syn in corpus luteum of early pregnancy
  • human placental lactogen (hPL), or human chorionic somatomammotropin: peptid, growth hormone-like and prolactin-like actions during pregnancy
  • estriol
  • progesterone
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14
Q

Name the pancreas hormones, their classification, and major actions:

A

Pancreas

  • insulin (beta-cells): peptide, decrease blood glucose
  • glucagon (alpha-cells): peptide, increase blood glucose
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15
Q

Name the kidney hormones, their classification, and major actions:

A

Kidney

  • renin: peptide, catalyzes conversion of angiotensinogen to angiotensin I
  • 1,25-dihydroxycholecalciferol: steroid, increases intestinal absorption of Ca2+, bone mineralization
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16
Q

Name the adrenal medulla hormones, their classification, and major actions:

A

Adrenal medulla

  • norepi, epi: amines, actions of sympathetic ANS
17
Q

How are protein and peptide hormones synthesized?

A

DNA > mRNA (nucleus)

mRNA > preprohormone (ribosomes)

preprohormone > prohormone (ER)

prohormone > hormone (golgi)

hormone stored and secreted via secretory vesicles

18
Q

How are steroid hormones synthesized?

A
  • all produced as derivatives of cholesterol
  • either side chains, hydroxylations, aromatizations are added
  • synthesized within the adrenal cortex, gonads, corpus luteum, and placenta
  • lipid soluble, thus are not stored within endocrine tissue due to ability to pass through membrane
  • act on intracellular receptors at target tissues
19
Q

How are amine hormones synthesized?

A
  • all synthesized from tyrosine
  • catecholamines: syn via enzymatic conversion of tyrosine in cytosol and secretory granules; act through cell membrane associated receptors at target tissues

(L-tyrosine > L-DOPA > dopamine > norepi > epi)

  • thyroid hormones: syn via thyroid gland and stored as thyroglobulins in follicles within gland; cross cell membranes at target tissues and act through nuclear receptors

(L-tyrosine > MIT > DIT > thyroxine > triiodothyronine > rT3)

20
Q

What is the general half life of each hormonal sub-group?

A

(the more the hormone binds w/ a protein, the slower the metabolic clearance will be, aka longer half-life)

(MC = metabolic clearance ml/minute)

- thyroid:

~99% protein binding

- T4 has 6 day 1/2 life and 0.7 MC

- T3 has 1 day 1/2 life and 18 MC

*relatively long 1/2 lives*

- steroids:

cortisol: 94% protein binding, 100 min 1/2 life, 140 MC

testosterone: 89% protein binding, 85 min 1/2 life, 860 MC

aldosterone: 15% protein binding, 25 min 1/2 life, 1100 MC

*moderate 1/2 lives that range depending on hormone*

- proteins:

thyrotropin: little protein binding, 50 min 1/2 life, 50 MC

insulin: little protein binding, 8 min 1/2 life, 800 MC

antidiuretic hormone: little protein binding, 8 min 1/2 life, 600 MC

*relatively short 1/2 lives*

21
Q

What are the 2 mechanisms of hormonal secretion control?

A
  • neural: neural input to endocrine cell, signal causes increase/decrease in secretion (example: sympathetic preganglionic innervation of adrenal medulla, when stim causes release of catecholamines into circulation)
  • feedback: positive and negative, some element of endocrine will feedback either directly/indirectly on an endocrine gland
22
Q

Describe positive feedback within hormones:

A
  • a hormone stimulates further production of itself
  • rather rare in humans
  • examples: oxytocin production in post pit during labor; estradiol production during ovulation
23
Q

Describe negative feedback within hormones:

A
  • stimulus causes release of hormones whose effects inhibit further release of itself
  • more common in humans, this is how most hormones are controlled
  • example: testosterone production in testes

(side note: long loops go from peripheral gland to central organ controlling production, short loops go from 2nd > 1st tier or something similar, ultra-short loops act within the same organ/gland)

24
Q

Major endocrine axes:

A
25
Q

Describe how the first tier of the endocrine axes is regulated:

A
26
Q

How are hormone receptors regulated?

A
  • receptors confer specificity to hormone actions: hormone-receptor complex, generally high affinity due to low conc of hormones
  • responsiveness of target tissue is expressed in dose-response relationship: sensitivty (hormone conc that produces 50% of maximal response, EC50)
  • responsiveness can be changed in two ways: changing the # of receptors or changing the affinity of the receptors for the hormone
27
Q

Describe the adenylyl cyclase mechanism for hormonal signal transduction:

A
  • 1st messenger: hormones (ACTH, LH, FSH, TSH, glucagon) bind to the receptor that is coupled w/ a G protein
  • G protein becomes activated, GTP substituted for GDP on alpha subunit of Gs protein
  • primary effector (adenylyl cyclase) is activated and converts ATP > cAMP
  • cAMP (2nd messenger) accumulates and is converted to 5’ AMP (inactive)
  • cAMP also activates secondary effector, protein kinase A (PKA), which triggers the phosphorylation of proteins and physiological actions

(hormones: ACTH, LH, FSH, TSH, ADH (v2 receptor), HCG, MSH, CRH, calcitonin, PTH, glucagon, beta1/beta2 receptors)

28
Q

Describe the phospholipase C mechanism for hormonal signal transduction:

A
  • 1st messenger hormone (GnRH, TRH, oxytocin) bind to receptor that is coupled w/ Gq protein
  • Gq protein becomes activated, GTP substituted for GDP on alpha subunit of Gq protein
  • primary effector (phospholipase C) is activated and converts PIP3 > diacyglycerol (DAG) and IP3
  • IP3/DAG/Ca2+ (2nd messengers) activate secondary effectors, PKC or calmodulin, to produce physiologic actions

(hormones: GnRH, TRH, GHRH, angiotensin II, ADH (v1 receptor), oxytocin, alpha1 receptors)

29
Q

Describe the steroid mechanism for hormonal signal transduction:

A
  1. most hydrophobic steroids are bound to plasma protein carriers, only unbound hormones can diffuse into target cell
  2. receptors are in the cytoplasm or nucleus
  3. receptor-hormone complex binds to DNA and activates/represses one or more genes
  4. activated genes create new mRNA that moves back to cytoplasm
  5. translation produces new proteins for cell processes
  6. some steroid hormones also bind to membrane receptors that use second messenger systems to create rapid cellular responses

(hormones: glucocorticoids, estrogen, progesterone, testosterone, aldosterone, 1,25-dihydroxycholecalciferol, thyroid hormones)

30
Q

Describe the guanylyl cyclase mechanism for hormonal signal transduction:

A
  • peptide hormone binds to ligand on receptor
  • guanylyl cyclase is activated, and converts GTP > cGMP
  • cGMP either activates cGMP kinases in response to ANP, or results in relaxation of vascular smooth muscle in response to NO

(hormones: atrial natriuretic peptide (ANP), nitric oxide)

31
Q

Describe the tyrosine kinase mechanism for hormonal signal transduction:

A

two types:

  • receptor tyrosine kinases: intrinsic tyrosine kinase activity, when activated tyrosine kinase phosphorylates downstream proteins
  • tyrosine kinase-associated receptors: associate non-covalently to proteins that have kinase activity, when activated kinase phosphorylates downstream proteins

(hormones: insulin, IGF-1, growth hormone, prolactin)

NE (36 decks)

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