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5. ADV PHYS > Endocrinology intro > Flashcards

Endocrinology intro Flashcards

1
Q

define and features: hormones features

A
  • first messengers
  • released from endocrine cells into interstitial fluid -> diffuse into blood
  • alter function of target cells, which have receptor proteins for particular hormone
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2
Q

define and features: receptors

A
  • maybe transmembrane protein (hydrophilic hormone)

- or cytoplasm/ nucleus (lipophilic hormone)

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3
Q

define and features: agonists

A
  • ligands (chemicals) that bind to receptors

- produce SAME effect as hormone

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4
Q

define and features: antagonists

A
  • bind to receptor

- prevent function of hormones

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5
Q

define and features: signal transduction and eg.

A
  • binding of hormone to receptor initiates 2˚ messenger sys within cells
  • 2˚ messengers (Ca ions, cAMP etc.) constituents of cellular pathways producing hormonal effects within cell
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6
Q

hormone function: main functions

A
  • along w ANS maintain homeostasis
  • growth
  • reproduction
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7
Q

hormone function: controlling plasma glucose eg (5)

A
  • also aa, free fatty acids by
  • insulin
  • glucagon
  • Ad
  • cortisol
  • growth hormone
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8
Q

hormone function: control BP eg. (4)

A
  • Ad
  • angiotensin II
  • aldosterone
  • atrial natriuretic peptide (ANP)

work w ANS

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9
Q

hormone function: plasma osmolarity eg. (1)

A
  • aka water balance

- antidiuretic peptide

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10
Q

hormone function: GIT eg. (3)

A
  • ANS
  • enteric NS

peptide hormones:

  • gastrin
  • secretin
  • cholecystokinin (CCK)
  • many more
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11
Q

hormone function: appetite eg. (3) and affect what part (3)

A
  • leptin
  • ghrelin
  • CCK
  • etc
  • arcuate nucleus
  • nucleus accumbens (hypothalamus)
  • nucleus of solitary tract (NTS) in brain stem
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12
Q

hormone function: physical stress response eg. (2) and hormones (4)

A
  • Ad
  • cortisol
  • glucagon
  • growth hormone

eg. hypoglycaemia, physiological

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13
Q

hormone function: long term stress

A

cortisol

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14
Q

hormone function: growth and dev eg. (2)

A
  • growth hormone

- somatomedins (IGF1)

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15
Q

hormone function: production of sperm, ova (5)

A
  • oestrogen
  • progesterone
  • testosterone
  • follicle stimulating hormone
  • luteinising hormone
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16
Q

hormone secretion as 2˚ function of organ eg. (4)

A
  • heart
  • kidneys
  • adipose tissue
  • skeletal mm
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17
Q

peptide hormones: features

A
  • usually produced in series of steps from precursor protein
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18
Q

peptide hormones: eg. insulin

A
  • produced from preproinsulin (2x internal sulphide bonds for 3˚ structure)
  • signal sequence removed = proinsulin
  • internal portion of protein molecules removed = insulin
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19
Q

peptide hormones: sig of signal sequence for insulin

A
  • directs proteins that are to be secreted to endoplasmic reticulum for further processing
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20
Q

peptide hormones: POMC eg.

A
  • precursor of many peptide hormones (pro-opiomelanocortin) POMC
  • found in pituitary cells, various cels in hypothalamus
  • cleaved to prod diff biologically active peptides
  • product depends on proteases/peptidases in cell
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21
Q

peptide hormones: POMC inside ant pituitary cell result

A
  • produce ACTH

- causes cortisol release from adrenal gland

22
Q

peptide hormones: POMC inside hypothalamus prod

A
  • å MSH (appetite control)
23
Q

peptide hormones: POMC released in other areas of brain prod

A
  • endogenous opioid ß endorphin
24
Q

peptide hormones: stored in

A
  • membrane bound vesicles
  • when triggered released by exocytosis (fusing of vesicle membrane w plasma membrane)
  • peptides r hydrophilic, transported dissolved in plasma
25
Q

peptide hormones: growth hormone (GH) sig

A
  • hydrophilic peptide

- travels to plasma bound to protein cleaved from membrane-bound GH receptor, acts like carrier protein

26
Q

peptide hormones: function of GH carrier

A
  • bound in circulation
  • reg conc fo free (active form) and bound GH
  • prolong GH half life in plasma
  • modulate GH bioactivity through competition w membrane bound receptors
27
Q

catecholamines:

A
  • hormones prod from peptide tyrosine
  • incl dopamine, Ad, NAd
  • like peptide hormones: stored in membrane bound vesicles
  • released by exocytosis
  • hydrophilic
  • transported dissolved in plasma
28
Q

mechanism for control of cell function by hormones: features

A
  • can’t cross cell membranes
  • act by binding to receptor inserted within plasma membrane of target cells
  • activation and initiates chain of reaction within cell (signal transduction)
  • eg. peptide hormones regulate transcription of particular genes in nucleus, therefore alter rate of prod of specific proteins
29
Q

mechanism for control of cell function by hormones: message generation involves

A
  • activation of enzymes within cytoplasm = prod biological response
30
Q

mechanism for control of cell function by hormones: ligand gated ion channels features

A
  • hormone receptors can be ion channels (eg. transporting Na, K, Cl, Ca) inserted into cell membrane, binding of hormone open/closes channel
  • affects cell by changing electrical properties of cells
31
Q

mechanism for control of cell function by hormones: eg. Ca ligand gated channels

A
  • allow influx of EC Ca and increase in cytoplasmic Ca is cellular signal
  • when enter cell, many effects: change electrical properties of cells, causing mm contraction
  • secretion by exocytosis
32
Q

mechanism for control of cell function by hormones: protein kinases (Ca bound)

A
  • Ca bound to cellular protein calmodulin also activate class of enzymes: protein kinases
  • they add phosphate groups (HPO4-) cont from ATP to enzymes
  • activate/ inhibit function of particular enzymes, alter cell metabolism
33
Q

mechanism for control of cell function by hormones: kinase enzymes incl tyrosine kinase receptor

A
  • vital part of membrane receptor protein in plasma membrane
  • eg. tyrosine kinase receptor
  • hormone binds to receptor, kinase phosphorylates tyrosine aa = cause multiple effects
34
Q

G proteins: mechanism

A
  • peripheral proteins (INNER surface)
  • no hormone present: guanosine disphosphate (GDP) bound to G protein
  • hormone attached to receptor: ‘regulatory’ subunits (ß and gamma) detach,
  • guanosine triphosphate (GPT) bind to active å subunit
  • activated subunit will alter function of another membrane bound protein (channel, or adenylate cyclase)
35
Q

G proteins: adenylyl/ adenylate cyclase features

A
  • converts cytoplasmic ATP into cyclic AMP (cAMP)

- cAMP activates kinase enzyme (protein kinase A)

36
Q

phospholipase C: features and activated mechanism

A
  • å subunit GPT complex also bind to phospholipase C: integral protein embedded in plasma membrane
  • when activated breaks membrane phospholipid PIP2 into IP3: dissolves cytoplasm
  • DAG retains 2 hydrophobic C-H chains
  • remains within lipid bilayer of membrane
37
Q

phospholipase C: when IP3 binds to Ca channels

A
  • in membrane of endoplasmic reticulum (SR in mm) opens and releases Ca stored within organelle
  • increased Ca conc. many cell metabolism effects
38
Q

phospholipase C: DAG activates

A
  • in membrane activates protein kinase C

- will phosphorylate to alter functional state of cell

39
Q

phospholipase C: Ad and glucagon in G protein mediated pathway

A
  • in liver cell
  • increase conc glucose in plasma
  • Ad binds to ß adrenergic receptors , G protein dissociates, å subunit binds GTP activates adenylate cyclase
  • cAMP prod activating protein kinase A, phosphorylates glycogen phosphorylase (enzyme converting glycogen (stored glucose) to glucose)
40
Q

peptide hormones, catecholamines, gene transcription: list peptide hormones (3)

A
  • insulin
  • glucagon
  • GH
  • others
41
Q

peptide hormones, catecholamines, gene transcription: features

A
  • peptide hormones, catecholamines change lvls of cell proteins (enzymes, transport proteins) by altering DNA transcription in nucleus
42
Q

peptide hormones, catacholamines, gene transcription: glucagon release eg.

A
  • released due to low plasma glucose
  • glucagon binds to receptors on plasma membrane of liver cells
  • initiates sequence ultimately activating protein kinase A
43
Q

peptide hormones, catacholamines, gene transcription: protein kinase A for glucagon

A
  • activates enzymes already in cytoplasm, releasing glucose from glycogen
  • cAMP also releases catalytic subunits from PKA
  • enter nucleus and phosphorylate transcription factors esp cAMP response element binding protein (CREB)
  • transcription of genes for enzymes needed: gluconeogenesis
44
Q

peptide hormones, catacholamines, gene transcription: sig of glucagon

A
  • increases plasma glucose rapidly through glycogenesis
  • by activating enzymes already present in plasma
  • slowly upreg prod of proteins that produce glucose via gluconeogenesis
45
Q

peptide hormones, catacholamines, gene transcription: gluconeogenesis general

A
  • making new glucose from substances such as lactate and certain aa
46
Q

peptide hormones, catacholamines, gene transcription: why need intermediate reactions- hormone binding to effects?

A
  • multiple steps
  • control many diff functions and pathways within one cell by 1 hormone
  • amplify signal initiates by binding of hormones
  • so messenger molecules lead to phosphorylation of millions of proteins
47
Q

steroid hormones: features

A
  • hormones prod from cholestrol: hydrophobic, lipophillic
  • can cross lipid bilayers/ cell membranes
  • can’t be stored in vesicles
48
Q

steroid hormones: rate of release

A
  • depends on rate of synthesis from cholesterol
  • derived directly from LDLs (low density lipoproteins) in plasma or
  • stockpiled cholesterol esters that are lipophobic = can be stored in vesicles within cells
49
Q

steroid hormones: bound hormones

A
  • can’t dissolve in plasma, carried bound to protein (binding globulins)
  • bound hormone buffers conc of free hormone (active form)
  • amount of free hormone depends on conc of hormone, conc of carrier, affinity of carrier for hormone
50
Q

thyroid hormones: features

A
  • hydrophobic, lipophilic containing iodine
  • 90% output in form of T4 (thyroxin, tetra iodothyronine), remainder= T3 (triiodthryonine)
  • thyroxine binding globulin binds T3/4 to allow hormones be dist by plasma
  • maintains lrg reservoir of T4 and prevent loss through kidney (preserves iodine)
  • active form T3 9even T4 changed to this) converted in periphery usually by target cells
51
Q

steroid/thyroid hormones: mechanism for cell function- features

A
  • hormone diffuses through lipid bilayer and bind to receptor molecules in cytoplasm/ nucleus
  • hormone receptor complex (HR) bind to hormone response element (HRE) where specific DNA sequence located near promoter region of gene
  • once bound to HRE, HR recruits co-activators: alter chromatin structure to unravel DNA from histones, expose it to transcription factors
  • co-activator activates transcription factor to increase pord of mRNA required for prod of desired protein
52
Q

steroid/thyroid hormones: mechanism for cell function- eg. aldosterone

A
  • most aldosterone carrier bound in plasma
  • crosses plasma membrane of cells of distal tubule, connecting duct to kidney
  • once inside, binds to carrier protein
  • hormone receptor complex enters nucleus where binds to HRE in DNA
  • complex upreg transcription of mRNA for mitochondrial enzymes (more ATP), Na/K exchange pump proteins, luminal Na and K channels
    = more Na reabsorbed by kidney while more K is excreted

5. ADV PHYS (10 decks)

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