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ANAT322 > lect 1-3 > Flashcards

lect 1-3 Flashcards

1
Q

what is endocrine chemical communication?

A

secretory cells secrete in blood stream and travels to distant target cells

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2
Q

what are features of endocrine glands. name some glands

A

ductless. fenestrated capillaries.
pituitary, thyroid, adrenal glands

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3
Q

what is neuroendocrine chemical communication?

A

neurosecretory nerve cells release neurohormones into the general circulation or in the hypothalamus-hypophyseal portal circulation

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4
Q

what are features of neuroendocrine communication?

A

reaches a large number of target cells;
indirect, relatively slow communication

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5
Q

what is the hypothalamus-hypophyseal portal circulation

A

blood stream from hypothalamus to anterior pituitary gland

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6
Q

describe the parvocellular system

A

small cells system: synthesis of hypophysiotropic hormones. released in ME

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7
Q

describe the magnocellular system

A

big cells system: produces neurohypophyseal peptides (ex OT and vasopressin)

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8
Q

name the 5 hypothalamic releasing factors

A

CRH corticotropin releasing hormone
GHRH growth hormone releasing hormone
GnRH gonadotropin releasing hormone
Somatostatin
TRH thyrotropin releasing hormone

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9
Q

what are the 2 neurohypophyseal peptides

A

oxytocin, vasopressin

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10
Q

what is POMC?

A

pro-opiomelanocortin, a prohormone precursor protein that gets processed in a tissue-specific manner to yield biologically active peptides

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11
Q

what is the endocrine master switch of the neuroendocrine system

A

pituitary gland

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12
Q

4 ways to control hypothalamic hormone release

A
  1. indirect stimulation/inhibition of neurosecretory cell via interneurons
  2. direct innervation via axo-dendritic / axo-somatic synapses
  3. pre-synaptic inhibition via axo-axonis synapses
  4. direct release of hypothalamic dopamine in portal blood stream
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13
Q

what is the most common neuroendocrine messenger?

A

peptides

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14
Q

when we say “central”, what do we mean?

A

hypothalamic

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15
Q

what takes longer, secretion or production of neuropeptides?

A

production

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16
Q

what happens in large dense-core vesicles?

A

processing, storage, and degradation of peptides.
cleaving out of bioactive peptide sequence.

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17
Q

what happens in rough ER for peptides production?

A

production of a large precursor proteins

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18
Q

where does the large precursor protein go to mature?

A

Golgi apparatus / TGN (actually LDCVs?)

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19
Q

what is always cleaaved off when it gets to the ER lumen ?

A

n-terminal signal peptide that signals to go to the ER

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20
Q

what is prohormone convertase?

A

enzyme that converts complex precursor proteins into active biological component

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21
Q

which prohormone convertase are present in neurons and endocrine cells?

A

PC1/PC3, PC2

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22
Q

what is special about pro-opiomelanocortin?

A

It can be cleaved at 7 different cleavage sites to give many different hormones:
ACTH, CLIP, JP, LPH, MSH, PC, beta-endorphin

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23
Q

what is precursor protein cleavage dependent on?

A

the location (ex hypothalamus, pituitary) of the endocrine cells or neurons, and mostly pH and PC expression

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24
Q

how is the pH in secretory granules?

A

acidic

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25
Q

what is ACTH and its role?

A

adrenocorticotropic hormone: reduces stress response by increase cortisol release by adrenals, which decrease CRH levels through neg feedback

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26
Q

what is found in LDCV’s membrane to help with post precursor protein processing?

A

prohormone convertases and proton pump that pumps protons in vesicles (more protons = low pH)

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27
Q

what happens to vesicles in the TNG?

A

get reduced

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28
Q

what are thinner axons or dendrites?

A

axons

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29
Q

what is white and gray matter?

A

white is myelinated axons
gray to nerve cell bodies; where neuronal processing happens

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30
Q

what defines cortex?

A

ordered structure of neurons cell bodies (has layers/laminae)

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31
Q

what defines nuclei?

A

neurons with similar topography and/or cellular morphology, connectivity, and neurochemical characteristics (expression of the same transmitters, peptides, etc.)

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32
Q

embryologically, what do the neural tube and neural crest become?

A

neural tube = CNS
neural crest = PNS

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33
Q

what makes the walls of the 3rd ventricle?

A

hypothalamus

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34
Q

what structure is the hypothalamus not directly linked to?

A

neocortex

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35
Q

what are the hypothalamus humoral inputs and outputs?

A

humoral inputs: steroids, peptide hormones at MBH, cytokines, neuropeptides
outputs: to the pituitary

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36
Q

what are hypothalamus neural inputs and outputs?

A

neural inputs: amygdala, limbic structures, lower brain stem, spinal cord, hippocampus, septum, thalamus
neural outputs: limbic structures, thalamus, brainstem

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37
Q

what are the hypothalamic main regions rostral to caudal?

A

preoptic – anterior – tuberal – mammillary

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38
Q

what structure is considered part of the periventricular hypothalamic zone even if it is not located in it? what system is it part of?

A

supraoptic nucleus SO
magnocellular system

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39
Q

what nucleus dominates the preoptic hypothalamic region?

A

medial preoptic nucleus (in medial zone)

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40
Q

what does the suprachiasmatic nucleus do?

A

biological master clock. gets direct input from retina

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41
Q

what is the difference between supraoptic and paraventricular neurons?

A

supraoptic has only magnocellular neurons, PVN has parvo and magno

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42
Q

how is the pituitary connected to the brain?

A

via median eminence and infundibulum

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43
Q

what happens if a pituitary tumor develops?

A

compressed hypothalamus

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44
Q

what are the pituitary hormones?

A

ACTH, beta-endorphin, alphaMSH, GH, prolactin, FSH, LH, TSH

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45
Q

what factor stimulates GH?

A

insulin-like Growth Factor-1 IGF-1

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46
Q

what does TSH do?

A

thyrotropin stimulates T3 and T4 secretion from thyroid gland

47
Q

what does FSH do?

A
  • stimulate primary follicle growth
  • stimulate estrogen secretion in females
  • stimulate sperm production
  • stimulate inhibin secretion in males
48
Q

what does LH do?

A
  • stimulate ovulation
  • stimulate corpus luteum formation
  • stimulates progesterone secretion in females
  • stimulates androgen secretion from leydig cells in males
49
Q

what does prolactin do?

A
  • initiates milk production and secretion
  • stimulates the gonads
50
Q

what are pituitary’s 2 embryological sources?

A

adenohypophysis (anterior pit) that arises from Rathke’s pouch in the roof of the developing pharynx.
neurohypophysis (post pituitary) originates from diencephalon base (neuroectoderm) and contain ME and infundibulum.

51
Q

which anterior pituitary cells are basophilic? (stain blue) what do they secrete?

A

gonadotropes (FSH, LH), thyrotrope (TSH)

52
Q

which anterior pituitary cells are chromophobic?

A

corticotropes (ACTH)

53
Q

which anterior pituitary cells are acidophilic? (stain orange)

A

somatotropes (GH)
lactotrope (PRL)

54
Q

GH acts on which structures?

A

liver (produce IGF) and bones

55
Q

what hormones are secreted by intermediate pituitary lobe?

A

melanocyte stimulating hormone (MSH), beta-endorphin

56
Q

what is beta-endorphin’s effect?

A

neuromodulator, circulating analgesic

57
Q

in which pituitary love does the intermediate lobe infiltrate?

A

in the posterior lobe

58
Q

what is the pituitary posterior (neural) lobe made of?

A

terminations of neurosecretory axons from the hypothalamo-hypophyseal tract and fenestrated capillaries into which the neurohormones are released (NO CELL BODIES ONLY GLIAL CELLS)

59
Q

what hormones are secreted by posterior pituitary?

A

OT and VP (ADH)

60
Q

what are herring bodies and where are they found?

A

swelling of axons / terminals full of neurohormone filled secretory granules in posterior pituitary

61
Q

what technique can herring bodies be stained with?

A

gomori technique (appear super dark)

62
Q

what are pituicytes? where can they be found?

A

specialized glial cells in posterior pituitary (only cells in post pit).
support neurosecretory axons
appear super pale

63
Q

where does the ME release hormones?

A

in hypophyseal portal veins that go to anterior pituitary and supply blood

64
Q

what is the definition of a hypophysiotropic hormone?

A

releasing and release-inhibiting hormone present in ME, whose concentration is higher in hypophyseal portal system than in general circulation and correlated with rate of release of a particular hypophyseal hormone

65
Q

another name for pituitary

A

hypophysis

66
Q

where is CRH found and what does it do?

A

PVN, PVa, Arc parvocellular neurons; stimulates ACTH. cam synthesize enkephalin, cholecystokinin CCK, neurotensin NT, VP, angiotensinII

67
Q

where is TRH found?

A

PVN, PVa, ARC

68
Q

where is GnRH found?

A

preoptic area, Arc. more restricted distribution

69
Q

where is GHRH found?

A

Arc

70
Q

where is somatostatin found?

A

POA, PVa, PVN, Arc. widespread distribution even outside hypothalamus. It is THE inhibitory hormone in pituitary.

71
Q

where is dopamine found?

A

Arc.
it acts on MSH release

72
Q

where are neurons that project to ME located?

A

anterior portion of periventricular zone around 3rd ventricle

73
Q

name arteries/veins of the hypophysial blood supply?

A

superior hypophyseal artery: outer zone of the median eminence. recievese hypothalamic hormones, give rise to:
hypophyseal portal veins: carry hypophysiotropic hormones in the anterior pituitary
inferior hypophyseal artery: blood supply to posterior pituitary
sup, lat, inf hypophyseal veins: drain blood from all pituitary in cavernous sinus

74
Q

where is ME located? what is a characteristic?

A

mediobasal hypothalamus MBH.
open blood-brain barrier (fenestrated capillaries): circumventricular organ

75
Q

what do circumventricular organ lack of blood-brain barrier do?

A

allows free diffusion of macromolecules between plasma and interstitial fluid

76
Q

what characterized the 2 layers of ME?

A

internal layer is not open. it is where axons from magnocellular neurons are
external layer is open: site of secretion. has parvocellular neurons

77
Q

how can parvo vs magnocellular neurons be identified in the lab?

A

parvo carry CRH
magno carry OT and VP

78
Q

what are the 3 ways to feedback control of hypothalamic hormone release?

A

long: from organ through hormones or sensory neuronal input
short: through pituitary hormones acting directly on hypothalamus
ultrashort: auto or paracrine action of hypothalamic hormone within one nucleus or through intra-hypothalamic projections

79
Q

many neuropeptides require what toxin to be visualized in cell bodies>

A

colchicine (depolarizes microtubules to inhibit axonal transport)

80
Q

what does adrenalectomy cause?

A

CRH accumulation and overproduction due to removal of target feedback from adrenal cortex

81
Q

what and where do magnocellular neurons mainly secrete?

A

OT and AVP from PVN and SON neurons to terminals and varicosities in posterior pituitary

82
Q

what is called the “intermediate” between AVP and OT?

A

vasotocin (isoleucin at pos 3 like OT, arg at pos 8 like VP)

83
Q

what caused higher vertebrate to have both VP and OT?

A

gene duplication event early in vertebrate evolution

84
Q

hat are AVP and OT always found and released with?

A

neurophysins: byproduct of the maturation cleavage (neurophysin I with OT, II with AVP).
stainable material in herring bodies

85
Q

why do we think OT and AVP were formed by gene duplication and inversion?

A

both genes sit in inverse order with inverted reading frame orientation

86
Q

in what exon is OT and AVP’s hormone sequence contained

A

exon 1

87
Q

what does the OT and AVP precursor protein contain?

A

signal peptide, the hormone sequence
proper, a consensus sequence (gly-lys-arg) for proteolytic maturation, and neurophysin

88
Q

what kind of receptors do OT and AVP bind to?

A

G-protein-coupled receptors

89
Q

what are the AVP receptors?

A

V1A, V1B, V2

90
Q

how do OT and AVP work biologically?

A

OTR, V1A, V1B are coupled to phospholipase C -> inositol triphophate and 1-2diacylglycerol -> Ca2+ release -> activate protein kinase C.
V2 is coupled to adenylate cyclase -> increase in cAMP

91
Q

describe OTR

A

g- protein-coupled receptor with 7 TM domains, extracellular N terminus

92
Q

all SON projection neurons are what type? where do they project

A

magnocellular; all express OT or AVP; project to posterior pituitary

93
Q

describe the distribution of OT vs AVP neurons in the PVN

A

OT neurons: rostral, less
AVP neurons: caudal and lateral, more numerous

94
Q

which is more homogenous between the SON and the PVN?

A

SON is more homogenous

95
Q

in rats, what portion of magnocellular neurons are accessories?

A

1/3

96
Q

what signal do OT neurons get to stimulate uterine contractions?

A

norepinephrine neurons that get mechanosensory info

97
Q

where do OT neurons get info from to send antidiuretic signal

A

baroreceptors and paraventricular organs, CCK, send info to NSTm VLM

98
Q

is OT and antidiuretic hormone?

A

NO ONLY AVP IS

99
Q

what is the main stimuli for vasopressin release?

A

plasma osmolality

100
Q

where are central osmoreceptors located?

A

3rd ventricle anterior wall, in subfornical organ SFO and OVLT

101
Q

what cranial nerves carry info from peripheral baro and osmoreceptors?

A

IX and Xth

102
Q

all this osmolarity input goes where?

A

mainly to PVN

103
Q

what is AVP’s main action?

A

promoting water reabsorption in collecting tubules by stimulating aquaporins insertion

104
Q

volume or pressure drops, what does it do to vasopressin?

A

increase plasma angiotensin II, activates baroreceptors -> increases vasopressin concentration in plasma. it increases vasoconstriction

105
Q

what receptors do AVP neurons get hypovolemia signal?

A

stretch and baroreceptors in the aortic arch

106
Q

what is angiotensin precursor?

A

angiotensinogen (cleaved by renin pro-hormone convertase)

107
Q

what is angiotensinogen effect?

A

increase aldosterone, increase NE = increase VP release = increase renal water retention

108
Q

AVP is colocated in magnocelullar neurons with what hormone?

A

Apelin

109
Q

are apelin and AVP in the same vesicles?

A

no

110
Q

where is apelin expressed (w avp)

A

SON and PVN neurons and in ME

111
Q

what are apelin’s diuretic effect?

A

reduces plasma AVP and increases diuresis (opposit of water reabsorption!)

112
Q

what happened to water deprived rats apelin and AVP levels?

A

increase in apelin AND AVP neurons activity

113
Q

what is the increase in apelin in neurons of water deprived rats due to?

A

increased accumulation of apelin due to decreased secretion, inhibited by AVP (V1 R activation)

114
Q

what happens to magnocellular cells plasticity during lactation and dehydration?

A

withdrawal of astrocytic processes to allow for direct apposition of somatic and dendritic membranes

ANAT322 (10 decks)

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