EXAM 2: Lecture 9,10 Flashcards
(109 cards)
1
Q
endocrine systems evolved from
A
single endo cells dispersed throughout body into specific regionalization of endo cells
2
Q
neurons
A
synapses on capillaries and possesses larger vesicles; hormones are NT
3
Q
modified epithelium
A
stand alone organs or embedded in other organs
4
Q
rare endo system
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single endo source, single hormone, single target
5
Q
benefits of endo systems
A
crosstalk between signaling pathways
functional redundancy (multiple hormones regulate complex physio)
robustness and adaptability (change as animal changes)
non-linear
6
Q
functional redundancy
A
critical physio processes are under control of multiple hormones
- presence of many signals needed to elicit maximal physio effectiveness
- interuption of 1 signal can be compensated by others
- multiple hormones may control same process and all together have greater effect than alone
7
Q
robustness of endo systems
A
must be adaptable because animals are subject to change
- aging/disease/weight gain
- systems change sensitivity and cross talk between other pathways
- animals are not static nor are endo cells; musta adapt as body changes
8
Q
non-linear ness of endo systems
A
can’t predict output from input
- complexity
- no direct one to one relationship
9
Q
crosstalk of endo systems
A
hormone A stimualtes AC; hormone B inhibits it in same cell
10
Q
master switches
A
transcription factors that drive organization of endocrine systems
PAX6 TF
genes controlling endo systems coevolved with genes underlying homeostatic control of physiology
11
Q
myriad
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inputs to same place, redundancy, integration
12
Q
vertebrates
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hypothalamus/pituitary
13
Q
invertebrates
A
p glands within the body
14
Q
driver nodes
A
endo systems have these which are essential control points that are centered on cells releasing hormones
15
Q
vertebrates: HPA
A
hypothalamus/pituitary axis
with additional endo organs, tissues, bigger, faster, developed CNS
16
Q
HPA
A
necessary for animals to be verts
gives verts a close association between endo and nervous tissue; central role of CNS in collecting peripheral and internal info
17
Q
invertebrates: no HPA
A
endo tissues outside CNS, smaller, slower, less sophisticated
18
Q
sponges
A
animal-specific TFs, structural proteins to construct endo cells
no endo cells; no blood
DO produce signals to coordinate physio
19
Q
HPA info
A
hormone secreting cells in the same place; allows for finer control of hormone release
hormones are peptides, AA, proteins
20
Q
HPA is
A
collections of hypothalamic neurons (nuclei) collect info from interior/exterior and send messages to pituitary
21
Q
two types of hormones in HPA
A
releasing hormones
inhibiting hormones
22
Q
releasing hormones
A
cause release of pituitary hormones
GHRH
GnRH
CRH
TRH
23
Q
GHRH
A
growth hormone releasing hormone
protein
24
Q
GnRH
A
gonadotropin releasing hormone
peptide
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CRH
corticotropin releasing hormone
peptide
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TRH
thyroid releasing hormone
peptide
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inhibiting hormones
block release of hormones onto pituitary
PIH
SS
28
PIH
prolactin inhibitory hormone
dopamine
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SS
somatostatin
peptide
30
blood flow in HPA
infundibulum: capillary bed that carries hormones to anterior pituitary
- second capillary bed within anterior pituitary that carries hormones to general circulation
some neurons secrete hormones into infundibulum
other neurons project axons to post pituitary where they synapse on capillary bed
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synapses in HPA
PO, SO
project and release in infundibulum
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synapses in HPA
PV
projects and releases in posterior pituitary
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anterior pituitary
under control of RH and IH released by hypothalamic nuclei
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cell types of anterior pitutiary
```
somatotropes
corticotropes
thyrotropes
gonadotropes
lactotropes
```
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somatotropes
GH
30-40%
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corticotropes
ACTH
20%
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thyrotropes
TSH
3-5%
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gonadotropes
LH/FSH
3-5%
39
lactotropes
Prl
3-5%
40
posterior pituitary
hypothalamic cells in supraoptic and paraventricular nuclei terminate onto capillary beds here
Oxy/ADH produced by separate cells and released directly into blood
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GH
regulates growth
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TSH
stimulates thyroid to release thyroxine
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ACTH
adenocorticotropic hormone
stimulates steroid synthesis by adrenal
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LH/FSH
gonadal regulation
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Prl
volume regulation
46
SS
inhibition of TSH/GH release
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advantages to complexity of endocrine systems
two decision modes, hypothalamus and pituitary
arrangement may best mimic physio it controls
arrangement may minimize noise by phase-locking/entrainment
some animals don't have HPA ; over engineering
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two decision modes: hypothalamus and pituitary
independently collect info from multiple sources
pituitary: yes/no decision to secrete hormone or not
feedback occurs at both levels
physio change does not provide feedback, pituitary hormone blood levels do
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HPA evolution
two levels: anatomical and hormonal
tests:
whole genome screens
immuno screens
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whole genome screens
look for peptides/proteins that share at least 60% homology with known HPA hormones
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immuno screens
look for cross-reactivity between AB raised against vertebrate hormones
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amphioxus
invert; small marine animal in warm coastal waters
- shallow groove near rudimentary NS
- has CYP P450s, immunoreactive peptides that cross react with LH, CCK, enekephalin, Pit1, TF
NEEDED FOR HPA DEVELOPMENT
environment is static, lack of change removes need for HPA
rudimentary pituitary has no cytological differences between cells; lack of regionalization
** presence of GnRH-like, ACTH-like, TSG-like peptides
53
HPA evolution
HPA present in all verts
pituitary NOT in all inverts
hypothalamic hormones older than HPA; found in inverts and verts without an HPA (GOF/LOF)
pituitary is vert invention but with old hormones
methods to which hypothalamic info goes to pituitary differs
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evolution of HPA is likely due to
optimization of communication between hypothalamus and pituitary while allowing hypothalamus and pituitary to inc. in size and complexity
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methods of hypothalamic info to pituitary:
agnatha
no direct link
hormones diffuse through general blood supply
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methods of hypothalamic info to pituitary:
teleosts
direct innervation of pituitary cells by hypothalamic neurons
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methods of hypothalamic info to pituitary:
mammals
release of hypothalamic hormones into portal blood supply of median eminence and then to pituitary
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lamprey info
ancient lineage of jawless fish
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lamprey endo system
start to see cells that look like hormone secreting cells in mammalian pituitary
development of nuclei of cell bodies within rudimentary hypothalamus
immunoreactive and in silico proof that GH, prl, and LH are produced and secreted --> diffusive link between hypothalamus and pituitary
60
elasmobranchs info
cartilaginous fish
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elasmobranchs hormonal evolution
possess MCH/MSH and other hormones not found in other vertebrates
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elasmobranchs anatomical evolution
pituitary clearly differentiated into diff areas; hypothalamus has pars ventralis and saccus vasculosus that secretes MCH/MSH
high interdigitation of hormone secreting cells and neurons, *no evidence of regionalization*
diffusive connection between hypothalamusa nd pituitary
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teleosts anatomical evolution
direct innervation of pituitary cells by hypothalamic neurons
no pars tuberalis
in other fish: clear separation between hypothalamus and pituitary
greater regionalization of hormone-secreting cells in anterior pituitary
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teleosts hormonal evolution
two types of GTH
production of stanniocalcin (unique to fish)
-GOF mutation
HPA hormones are also NT
overlap between CNS/HPA
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teleost evolution
one decision center
GnRH releasing neurons are phase-locked with pituitary secreting GTH hormones
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amphibians info
transition from teleost to mammalian
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amphibians anatomical evolution
like mammals: median eminence and secretion of hormones into portal blood supply
- like animals: clear sexual dimorphism of hypothalamic nuclei
- like teleosts: direct innervation of hormone secreting cells in pars intermedia (pituitary)
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amphibians hormonal evolution
unique pituitary hormone:
arginine vasotocin
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arginine vasotocin
amphibians pituitary hormone
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reptiles anatomical evolution
similar to mammalian HPA
- no direct innervation of pituitary cells
- hypothalamus is missing some mammalian nuclei
- pituitary is differentiated into pars distalis, tuberalis, intermedia
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reptiles hormonal evolution
similar to amphibians with exception of arginine vasotocin -- mesotocin instead
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birds anatomical evolution
like mammalian;
- hypophyseal blood flow not identical to animals
- sexually dimorphic hypothalamus
- evidence for mammalian-like direct hormone secretion into posterior pituitary
- pituitary has no pars intermedia but a well developed pars tuberalis
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birds hormonal evolution
same as mammals
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mammals anatomical evolution
well developed hypophyseal blood flow, pars nervosa
- extensive regionalization of pituitary hormone secreting cells
- extensive regionalization of hypothalamic nuclei
- clear development of hypothalamic control of pituitary hormone release
- extensive development of distinct pituitary regions
75
mammals hormonal evolution
anterior pituitary: pars distalis, tuberalis, intermedia; large volume of hypophyseal blood flow
- clear regionalization of hypothalamic and pituitary hormone secreting cells
- two clear discriminators
- evidence for extensive info flow from CNS to hypothalamic nuclei
- hormones appear and disappear form HPA because of need
** regional stratification is separate from hormonal evolution
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pituitary stratification
tuberalis
intermedia
distalis
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pars tuberalis
Prl secreting cells
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pars intermedia
alpha-MSH
absent in whales, manatees, elephants, armadillos, beavers, adult humans, body hair, and melanocytes
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distalis
```
ACTH
TSH
GH
PrL
LH
FSH
```
80
hypothalamus stratification
extensive regionalization with distinct nuclei
suprachiasmatic, ventromedial, dorsomedial, posterior, supraoptic, periventricular, arcuate
sexually dimorphic
info flows as NT
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invertebrates anatomical evolution
corpus cardiaca and allata = hypothalamic equivalents
- neurohemal organs that secrete hormones into blood
- also endocrine cells
- no pituitary, no portal blood flow
82
pituitary hormones
```
oxytocin
ADH
LH
FSH
TSH
GH
PrL
ACTH
MSH
LPH
```
83
oxytocin
uterus, reproduction
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ADH
kidney, water retention
85
LH
testes/ovaries, steroidogenesis, gamete release
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FSH
testes/ovaries, steroidogenesis, follicle development
87
TSh
thyroid, thyroxine release
88
GH
bone, tissues, osmoregulation, tissue growth & development
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Prl
osmoregulation
90
ACTH
adrenal, steroidogenesis; glucocorticoids and androgen precursors
91
MSH
melanocytes, melanin production
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LPH
adipose, lipolysis
93
CRH family
demonstrates gene duplication and GOF/LOF
family found in vertebrates and invertebrates
41 AA peptide distributed in PNS and CNS
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fish CRH
urotensin
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mammals CRH
urocortin
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amphibians CRH
sauvagine
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vertebrates CRH
Ucn2 and Ucn3
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invertebrates CRH
DH
99
CRH peptide family
neurologically active peptides 38-42 AA
c and n term modification
amphiphilic
100
vertebrates CRH family
produced in hypothalamus, T lymphocytes and placenta
- placental release determines gestational length
pituitary: releases ACTH, beta-endorphin release, GPCR
control of physiological stress
101
CRH release
wide range of NTs that control CRH release is a measure of importance
release is a consequence of integration of autonomic and behavioral input into HPA
example of advantages of regionalization within CNS and endo systems
102
CRH receptors
secretin family GPCRs that arose by gene duplication
signal through cAMP/PKA
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CRHR1
brain, anterior pituitary
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CRHR2
less in CNS, more PNS with multiple splice variants
105
CRH binding protein (CRHBP)
highly conserved
secreted glycoprotein that binds CRH with high affinity
not subject to gene duplication
binds CRH and Ucn1
40-60% of CRH in CNS is bound to CRHBP
- limits availability
- attenuates ACTH release
acts to traffic receptor to cell surface
106
CRH physiology
control of stress, blood vessel diameter, thermoregulation, growth and metabolism, metamorphosis, reproduction
GOF
found in all verts, echinoderms, molluscs, annelids, arthropods
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CRH evolution
CHR1
3 rounds of duplication --> CRH2
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CRH evolution
CRH2
lost in placental mammals and teleosts
present in birds, lizards, platypus
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CRH evolution
in fish
evidence of gene duplications, LOF and GOF of paralogous genes for CRH, its receptor, and its BP
