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histology > unit 15 > Flashcards

unit 15 Flashcards

1
Q

what are endocrine glands

A

tissues in which hormone secreting cells make up most of the parenchyma

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2
Q

where are hormones exerting endocrine action released

A

into the interstitial and then enter the blood stream for transport

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3
Q

where are aggregates of secretory cells embedded

A

in highly vascularized CT, no ducts are associated with secretory cells

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4
Q

what is different about secretory cells

A

resemble epithelial cells but lack free surface

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5
Q

how are secretory cells usually arranged

A

into cords or clusters and surrounded by an extensive capillary network

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6
Q

where are secretory cells derived from

A

most from CNS, neural crest, or gut tube epithelium, a few have mesenchymal origin

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7
Q

what are the four types of hormones

A

glycoproteins (mostly water-soluble)
protein or peptide (water)
amino acid derivatives (water)
steroids (lipid)

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8
Q

anterior pituitary

A

composed of glandular, densely packed epithelium
derived from ectoderm
stains darkly
not directly attached to the hypothalamus
aka adenohypophysis

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9
Q

posterior pituitary

A

composed of neural secretory tissue
derived from neuroectoderm
less cellular, appears streaky, stains lightly
directly attaches to the hypothalamus
aka neurohypophysis

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10
Q

pituitary development

A
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11
Q

regions of the posterior pituitary

A

pars nervosa - larger portion
infundibulum - continuous with median eminence

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12
Q

anterior pituitary regions

A

pars distalis
pars intermedia
pars tuberalis

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13
Q

pars distalis

A

bulk of anterior pituitary, arises from thickened anterior wall of Rathke’s pouch
composed of strongly staining secretory cells surrounded by fenestrated capillaries and minimal CT with reticular fibers

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14
Q

pars intermedia

A

thin remnant of posterior wall of Rathke’s pouch, abuts the pars distalis

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15
Q

pars tuberalis

A

sheath of tissue around infundibulum, developed from thickened lateral wall of Rathke’s pouch

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16
Q

what are the 3 cell types found in pars distalis

A

acidophils (40%), basophils (10%), chromophobes (50%)

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17
Q

what are chromophobes

A

heterogeneous group of cells including stem/progenitor cells and degranulated acidophils & basophils

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18
Q

what are the two types of acidophils

A

somatotrophs and lactotrophs

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19
Q

somatotrophs

A

secrete somatotropin (aka GH)
GH increases metabolic rate, induces liver to produce insulin-like growth factor 1 (IGF-1), stimulate bone and muscle growth

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20
Q

what affects somatotrophs

A

stimulated by GHRH, inhibited by somatostatin

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21
Q

lactotrophs

A

secrete prolactin
promotes androgen secretion in males and mammary gland development/lactation in female
large polygonal cells with oval nuclei

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22
Q

what affects lactotrophs

A

no dedicated releasing hormone, various factors promote secretion though
dopamine inhibits secretion

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23
Q

what do acidophils contain

A

cytoplasmic secretory vesicles containing peptide! hormone product

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24
Q

what are the 3 types of basophils

A

corticotrophs, gonadotrophs, thyrotrophs

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25
Q

corticotrophs

A

synthesize POMC, precursor to ACTH
ACTH stimulates synthesis & release of hormones from adrenal cortex

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26
Q

what affects corticotrophs

A

secretion stimulated by CRH, inhibited by high plasma cortisol levels

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27
Q

gonadotrophs

A

secrete FSH and LH
stimulate follicle growth, ovulation, sex hormone production

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28
Q

gonadotrophs location

A

small oval cells with round eccentric nuclei, scattered throughout pars distalis

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29
Q

what affects gonadotrophs

A

secretion stimulated GnRH, inhibited by high plasma levels of sex hormones

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30
Q

thyrotrophs

A

secrete thyrotropin (TSH), acts on follicular cells of the thyroid gland to stimulate production of thyroid hormones

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31
Q

what affects thyrotrophs

A

secretion stimulated by TRH, inhibited by high plasma thyroid hormone levels

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32
Q

pars intermedia

A

contains colloid-filled cysts (Rathke cysts) lined by cuboidal cells and clusters of basophil-like cells

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33
Q

what are Rathke cysts

A

remnants of Rathke pouch

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34
Q

pars tuberalis

A

highly vascular area containing large vessels if the hypothalamohypophyseal portal system with associated small clusters/cords of cells associated with BVs
contains nests of squamous cells and small follicles lined by cuboidal cells

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35
Q

what does the superior hypophyseal portal system supply directly

A

pars tuberalis, infundibulum, median eminence (contains termini of neurosecretory neurons producing releasing inhibitory hormones

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36
Q

what does the superior hypophyseal artery form

A

primary fenestrated capillary plexus

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37
Q

where does the primary capillary plexus drain

A

hypophyseal portal veins

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38
Q

what do hypophyseal portal veins form

A

secondary capillary plexus in pars distalis

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39
Q

what surrounds acidophils, basophils, chromophobes

A

fenestrated capillaries

40
Q

what acts on pars distalis

A

releasing/inhibitory hormones

41
Q

where does the secondary capillary plexus drain

A

into hypophyseal veins

42
Q

is the posterior lobe of pituitary an endocrine gland

A

NO

43
Q

what is the infundibulum continuous with? what does it contain?

A

median eminence
axons of hypothalamic neurosecretory cells traveling as hypothalamic hypophyseal tract

44
Q

what does the pars nervosa contain

A

axons and termini of hypothalamic neurosecretory cells; axons terminate near capillaries of capillary plexus of nervosa

45
Q

where are peptide hormones produced? what is well developed in these cells?

A

in supraoptic nucleus and paraventricular nucleus cell bodies
Nissl bodies are well developed

46
Q

where are peptide hormones packed into? how are they transported?

A

into secretory granules
transported along axons and stored near and at axon termini in pars nervosa

47
Q

what are accumulations of secretory granules in the pars nervosa seen as

A

visible distentions, Herring or neurosecretory bodies, along axons and at termini
axons appear as streaks

48
Q

what are Herring bodies

A

groups of secretory vesicles containing granules of antidiuretic hormone (vasopressin) or oxytocin

49
Q

what are pituicytes

A

neuroglia cells that surround and support axons extending from hypothalamus
most abundant in pars nervosa
have round/oval nucleus
irregularly shaped cells with many branches

50
Q

antidiuretic hormone or vasopressin

A

increases permeability of collecting tubules to water and has an arteriolar vasoconstrictive action
mediated by cAMP

51
Q

where does pars nervosa receive blood from?
what do these arteries form?

A

inferior hypophyseal and trabecular arteries
capillary plexus in pars nervosa

52
Q

how do hormones released by Herring bodies enter the blood circulation

A

through capillary plexuses of inferior hypophyseal and trabecular arteries

53
Q

where does the pineal gland develop from

A

neuroectoderm of the posterior roof of diencephalon and remains attached via a small stalk

54
Q

what does the pineal gland do

A

relates light intensity/duration to endocrine activity, regulates circadian rhythm
produces melatonin

55
Q

what covers the pineal gland

A

capsule of pia mater
CT trabeculae extend from capsule into substance of gland, divide into lobules

56
Q

pinealocytes

A

melatonin producing cells, arranged in clumps/cords within lobules

57
Q

interstitial glial cells

A

closely resemble astrocytes, have elongated nuclei that stain more heavily the pinealocytes
found in perivascular areas and between groups of pinealocytes

58
Q

corpora arenacea

A

brain sand
calcified concretions

59
Q

thyroid gland structure

A

2 lobes connected via isthmus, surrounded by thin fibrous capsule which send septa deeply into gland

60
Q

hormones produced by thyroid

A

thyroid hormones T3, T4- control basal metabolic rate
calcitonin - helps regulate calcium and phosphate metabolism

61
Q

thyroid follicle

A

spherical, cyst like structures lined by simple epithelium (follicular epithelium)
structural and functional unit of thyroid

62
Q

what surrounds each follicle

A

a thin layer of CT containing fenestrated capillaries, epithelium ranges from cuboidal to low columnar

63
Q

what is colloid

A

gel-like material in center of follicle
T3 and T4 bound to thyroglobulin, a glycoprotein that is most abundant component of colloid

64
Q

how does the thyroid store its secretory products

A

extracellularly

65
Q

colloid volume/follicle size…

A

inversely correlated with follicle activity

66
Q

thyroid follicular cells

A

synthesize and secrete T4 and T3 in response to TSH from pituitary

67
Q

thyroid follicular cell structure

A

apical surface lines follicular lumen, in contact with colloid
basal surface rests on basal lamina adjacent to surrounding CT
lateral surface contains tight junctions
range from squamous to low cuboidal/columnar
abundant vesicles at apical surface and in apical cytoplasm

68
Q

where do cells reabsorb colloid? secrete T3/T4?

A

apical surface
basal surface

69
Q

thyroid follicular cells at EM level

A

apical rER, supranulcear golgi
apical microvilli
colloid resorption droplets
many lysosomes

70
Q

where are parafollicular cells located

A

found at periphery of follicle in interfollicular stroma, individually or in small clusters

71
Q

what do parafollicular cells contain

A

small, dense secretory granules containing calcitonin

72
Q

what is calcitonin secretion stimulated by

A

directly by high levels of calcium in blood, acts to decrease calcium concentration in blood

73
Q

parathyroid glands

A

4 glands embedded in posterior thyroid, encased in thin capsule which invaginates creating poorly defined lobules

74
Q

how are parathyroid cells organized

A

into cords/clusters surrounded by reticular fibers, BV, lymphatics, nerves

75
Q

what do parathyroid cells secrete

A

parathyroid hormone, maintains optimal concentrations Ca in blood and interstitial fluid
stimulated by declining serum calcium levels
released by exocytosis

76
Q

oxyphil cells

A

round large cells with relatively smaller nucleus, acidophilic cytoplasm
found singly or in clusters
function unclear

77
Q

adrenal glands

A

paired organs covered with dense CT capsule
parenchyma composed of secretory cells, stroma mostly reticular fibers, fibroblasts, microvasculature

78
Q

adrenal cortex

A

originates from mesoderm, parenchymal cells synthesize and secrete steroid hormones

79
Q

adrenal medulla

A

derived from neural crest
produced catecholamines

80
Q

3 concentric zones of adrenal cortex

A

zona glomerulosa
zona fasciculata
zona reticularis

81
Q

zona glomerulosa

A

small columnar/pyramidal cells organized into tightly packed ovoid clusters surrounded by capillaries
hormones secrete mineralocorticoids

82
Q

mineralocorticoids

A

regulate Na and K homeostasis
principle secretion is aldosterone (increases Na resorp, stimulates K excretion)
regulated by renin-angiotensin aldosterone system

83
Q

zona fasciculata

A

long cords 1-2 cell layers thick, large columnar or pyramidal cells separated by sinusoidal capillaries
abundant cytoplasmic lipid droplets that give cells a vacuolated appearance

84
Q

zona fasciculata hormones

A

secrete glucocorticoids in response to ACTH from pituitary which regulates gluconeogenesis and glycogenesis
principle secretion is cortisol

85
Q

zona fasciculata function

A

control carbohydrate, fat, and protein metabolism

86
Q

zona reticularis

A

smaller cells with deeply stained nuclei, arranged in network of irregular cords surrounded by wide capillaries
cells often dark, contain few lipid droplets in cytoplasm

87
Q

zona reticularis hormones

A

secrete weak androgens (DHEA, DHEAS, and androstenedione)
secrete some glucocorticoids, responsive to ACTH

88
Q

zona reticularis function

A

weak, masculinizing hormones

89
Q

adrenal medulla

A

derived from neural crest
functions as a modified sympathetic ganglion

90
Q

chromaffin cells

A

epitheliod (columnar) secretory cells that produce catecholamines, surrounded by capillaries
secrete epinephrine mostly, some norepinephrine
modified postgang symp neurons
innervated by myelinated, pregang symp nerve terminals

91
Q

ganglion cells

A

large round cells with prominent nuclei, found in clusters
axons extend to adrenal cortex and impact secretory activity, blood vessels and splanchnic nerves

92
Q

how are the effects of epinephrine mediated

A

by adrenergic receptors, multiple alpha and beta adrenergic receptors expressed in different target tissues

93
Q

what do the suprarenal arteries give rise to

A

short cortical and long medullary arteries

94
Q

short cortical arteries

A

form fenestrated arterial capillary plexus in subcapsular space and zona glomerulus
converge into cortical sinusoidal capillaries that traverse zona fasciculata, drain into fenestrated venous capillary plexus in zona reticularis and medulla

95
Q

long medullary arteries

A

traverse cortex and form sinusoidal capillaries in medulla to provide arterial blood

96
Q

what drains into central adrenomedullary veins? why are they unusual?

A

cortical and medullary capillary plexuses
tunica media contains abundant SM cells, contraction enhances efflux of hormones into circulation

97
Q

secretory cells and vasculature

A

histology (15 decks)

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