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Structures: Part Deux > LEC36: Endocrine System I > Flashcards

LEC36: Endocrine System I Flashcards

0
Q

what’s within endocrine II?

A

thyroid, C (parafollicular) cells, parathyroid, adrenal - cortex & medulla, pancreas - islets of langerhans, diffuse endocrine system

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1
Q

what is within endocrine I

A

pituitary, hypothalamus, pineal

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2
Q

exocrine duct formation and release

A

downgrowth of epithelium into CT > duct forms at surface > contents release from duct, at epithelium surface

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3
Q

endrocine duct formation

A

proliferation of cells, downgrowth into CT > breaks from epithelium > follicular endocrine gland forms w/ cord of cells/capillaries surrounding

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4
Q

endocrine follicle structure

A

ring of endocrine cells divided by epithelial cells in center; lumen in center; capillaries infiltrate CT between follicles

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5
Q

hormone defn

A

chemical substances synthesized by endocrine cells and secreted

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6
Q

3 ways hormones can effect cells once secreted

A

1) into bloodstream > distant target cells
2) into tissue space > adjacent or nearby target cell
3) onto own cell surface > own target cells

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7
Q

why hormones synthesized/secreted?

A

1) to influence metabolic activities of target cells

2) in conjunction w/ nervous system, coordinate & integrate fxns of all physiological systems

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8
Q

hormonal signaling mechanisms (3)

A

1) endocrine signaling
2) paracrine signaling
3) autocrine signaling

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9
Q

how endocrine signaling works

A

endocrine follicle gland has lumen, blood vessel goes through > hormone secreted into blood > attaches to membrane receptor or receptor in cytosol at distant target cell > tells distant cell to make hormone
i.e. pituitary hormones

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10
Q

how do paracrine signals work

A

endocrine cell inside hormone travels through CT > effect nearby cell, a few cells away from endocrine cell > hormone sits on membrane receptor to tell target cell to produce

i.e. somatostatin inhibits insulin secretion in islets of langerhans

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11
Q

how does autocrine signaling work

A

hormone/growth factor sits on membrane receptor of its own cell
i.e. insulin, TGF-beta

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12
Q

chemically, hormone types (3)

A

1) peptides and glycoproteins
2) steroids
3) amino acids

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13
Q

examples of peptides, glycoproteins hormones

A

hormones of pituitary, parathyroid, C cells of the thyroid, islets of Langernas and GI tract

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14
Q

examples of steroid hormones

A

hormones of adrenal cortex, ovary and testis

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15
Q

examples of amino acid (tyrosine) hormones

A

hormones of thyroid, adrenal medulla

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16
Q

hormonal distinguishment by morphology (2)

A

1) peptide/glyprotein hormone producing cells contain granules (electron dense on EM!), which store hormones
2) steroid hormone-producing cells store and release hormones into circulation right away (eosinophilic stain!), no granules for storage

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17
Q

endocrine glands whose sole functions are hormone production

A

pituitary, pineal, thyroid, parathyroid, adrenal

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18
Q

endocrine tissues found in association w/ organs which have other functions

A

pancreas, ovary, testis, kidney, liver

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19
Q

ovary’s exocrine function

A

release of ovum

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20
Q

testis’s endocrine and exocrine functions

A

endocrine: testosterone
exocrine: sperm

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21
Q

kidney’s endocrine and exocrine functions

A

endocrine: make renin, prostaglandins
exocrine: renal tubule absorption/reabsorption into tubules

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22
Q

liver’s endocrine and exocrine functions

A

endocrine: makes glucose amino acid albumin, > circulation
exocrine: makes many metabolites which > metabolism, secrete bile to gall bladder

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23
Q

diffuse endocrine system

A

endocrine tissue > single hormone-producing cells diffusely scattered in digestive, respiratory systems

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24
Q

where is pituitary located

A

beneath floor of III ventricle, connected to hypothalamus

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25
Q

where is diencephalon, what does it consist of?

A

between forebrain and midbrain
forms wall of ventricle or cisterna
consists of thalamus, hypothalamus, epithalamus

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26
Q

which part of thalamus and of hypothalamus forms floor of III ventricle?

A

ventral part of thalamus

median eminence of hypothalamus

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27
Q

where does floor of III ventricle extend into?

A

site of pituitary gland

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28
Q

why is pituitary gland “master” gland?

A

although tiny, it controls most of endocrine functions of the body

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29
Q

where does pituitary gland sit?

A

in hypophyseal fossa, a bony depression of the sella turcia (hump) of the sphenoid bone (in middle cranial fossa)

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30
Q

where is median eminence of hypothalamus, what does it connect to?

A

between/just posterior to optic chiasma

connects by stalk to pituitary gland

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31
Q

2 parts of pituitary gland

A

1) adenohypophysis, anterior pituitary, aka pars distalis - glandular
2) neurohypophysis, posterior pituitary, aka pars nervosa

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32
Q

pars distalis means

A

hormones of anterior pituitary

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33
Q

pars distalis contains

A

most endocrine cells of pituitary

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34
Q

pars nervosa means

A

hormones of posterior pituitary

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35
Q

parts of anterior pituitary

A

1) pars distalis
2) pars tuberalis
3) pars intermedia

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36
Q

parts of posterior pituitary

A

1) pars nervosa
2) infundiibulum
3) median eminence

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37
Q

what does posterior pituitary (neurohypophysis) develop from

A

nervous tissue of hypothalamus

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39
Q

what does anterior pituitary (adenohypophysis) develop from

A

ectoderm of roof of the mouth

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40
Q

how does pituitary gland develop?

A

1) hypothalamus invaginates, grows down toward rathke’s pouch of fossa, becomes stalk, while neurectoderm tissue of roof of mouth grows toward hypoficial fassa
2) rathke’s pouch approaches pars nervosa; pouch space becomes narrow, forms pars distalis and pars intermedia

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41
Q

what does pars nervosa develop from?

A

distal end of hypothalamus

42
Q

what does rathke’s pouch become?

A

anterior part: anterior part of pars distalis

posterior part: pars intermedia

43
Q

where does rathke’s pouch develop from?

A

roof of the mouth

44
Q

what is between pars nervosa and pars distalis?

A

pars intermedia

45
Q

how/where does pituitary gland connect to the hypothalamus?

A

pars nervosa connects to stalk to hypothalamus

functional and physical connection

46
Q

how/why do pars nervosa and pars distalis stain differently?

A

pars distalis stains darker b/c has endocrine cells

47
Q

characteristics of pars distalis

A

1) endocrine cell clusters
2) reticular fibers, Type III collagen, support
3) FENESTRATED/SINUSOIDAL CAPILLARIES throughout for rapid diffusion of hormones into circulation

48
Q

chromophils

A

affinity for dye

1) acidophils- affinity for acidic dye
2) basophils- affinity for basic dyes

49
Q

chromophobes

A

degranulated acidophils/basophils, granules don’t stain by antibodies

50
Q

how many populations/types of endocrine cells are there

A

5

51
Q

how would you localize endocrine hormones

A

immunocytochemical staining

make an antibody against a hormone, localize it

52
Q

why 6 hormones but 5 cell types

A

because both FSH and LH expressed by 1 cell type, gonadotrophs

53
Q

6 hormones localizable with immunocytochemical staining

A

growth hormone, prolactin, corticotropin (ACTH), thyrotropin (TSH), follicle stimulating hormone (FSH), luteinizing hormone (LH)

54
Q

how can you tell anterior pituitary cell in EM?

A

anterior pituitary hormones are stored in granules, which has marker that stains positively

55
Q

how are endocrine cell types named?

A

for the hormones they secrete

56
Q

acidophils of pars distalis?

A

1) somatotrophs

2) mammatrophs

57
Q

what do somatotrophs secrete, what proportion is this of all pars distalis?

A 
growth hormone (GH) 
50%
58
Q

what do mammatrophs secrete, what proportion is this of all pars distalis?

A

prolactin

20%

59
Q

basophils of pars distalis?

A

1) corticotrophs
2) thyrotrophs
3) gonadotrophs

60
Q

what do corticotrophs secrete, what proportion is this of all pars distalis?

A

corticotropin (ACTH)

20%

61
Q

what do thyrotrophs secrete, what proportion is this of all pars distalis?

A

thyrotropin (TSH)

5%

62
Q

what do gonadotrophs secrete, what proportion is this of all pars distalis?

A

1) follicle stimulating hormone (FSH)
2) luteinizing hormone (LH)
5%

63
Q

how are pars distalis hormones controlled?

A

secretion of pars distalis hormones controlled by HYPOTHALAMUS via HYPOTHALAMIC RELEASING or INHIBITING HORMONES

64
Q

function of hypophyseal (pituitary) portal system?

A

in pituitary gland

provides anatomical-function link between hypothalamus & pars distalis of anteiror pituitary

65
Q

blood supply to pituitary gland?

A

inferior & superior hypophyseal artery - branchs of coratid

66
Q

how does hypophyseal portal system work

A

inferior/superior hypophyseal arteries enter pituitary gland at pars distalis
> break into vein, venule
> go to endocrine cells of pars distalis, surround capillaries
> hormones > circulation

67
Q

what do neurosecretory cells in hypothalamus do?

A

control pars distalis hormone secretion by making releasing and inhibiting hormones

68
Q

what do releasing and inhibiting hormones of hypothalamus neurosecretory cells target?

A

anterior pituitary hormones

therefore effect target organ cells

69
Q

what are the hypothalamic hormones?

A

1) GH-releasing hormone
2) corticotropin-releasing hormone
3) TSH-releasing hormone
4) gonadotropin-releasing hormone
5) dopamine
6) somatostatin

70
Q

GH-releasing hormone function?

A

stimulates GH release

71
Q

corticotropin-releasing hormone function?

A

stimulates ACTH release

72
Q

TSH-releasing hormone function?

A

stimulates TSH release

73
Q

gonadotropin-releasing hormone function?

A

stimulates FSH and LH release

74
Q

dopamine function?

A

INHIBITS prolactin release - unique b/c inhibition!

75
Q

somatostatin function?

A

aka global inhibitor - always inhibits, wherever it acts
INHIBITS GH release
ex: inhibits glucose release in pancreas

76
Q

when is pars intermedia well pronounced?

A

in animals, not in humans

77
Q

what does pars intermedia secrete

A

2 types of melanocyte-stimulating hormone:
B-MSH: skin pigmentation
A-MSH: anti-appetite

78
Q

what are melanocyte-stimulating hormones product of?

A

pro-opiomelanocortin (POMC)

79
Q

what do pars intermedia granules and corticotrophs both synthesize

A

pro-opiomelanocortin

80
Q

what can pro-opiomelanocortin split into

A

1) ACTH
2) lipotropins for lipid metabolism
3) endorphins for endogenous opioids
4) MSHs B and A for skin pigmentation and anti-appetite

81
Q

what hormones does pars nervosa secrete

A

1) antidiuretic hormone (ADH; vasopressin)

2) oxytocin

82
Q

what do pars nervosa hormones bind to

A

a carry protein neurphysin

83
Q

what produces ADH?

A

neurons in the supraoptic nuclei of the hypothalamus

84
Q

what produces oxytocin?

A

neurons in the paraventricular nuclei of the hypothalamus

85
Q

what is the hypothalamohypophyseal tract

A

axon tract that carries hormones (ADH, oxytocin) from neuron of hypothalamus to pars nervosa of pituitary

86
Q

ADH function?

A

water absorption in collecting ducts, convoluted tubules of kidneys

87
Q

oxytocin functions?

A

1) acts on myoepithelial contraction- physically expelling milk from mammary glands
2) uterine contraction

88
Q

what are pituicytes?

A

neuroglia - supporting cells of hypothalamo-hypophyseal tract

89
Q

what is hypothalamo-hypophyseal tract made of

A

100,000 unmyelinated axons

90
Q

what are herring bodies

A

swellings along axon of hypothalamo-hypophyseal tract; collecting sites of granules of hormones ADH and oxytocin, which bind in herring bodies to neurophysin

91
Q

what controls release of ADH/oxytocin, where are they released?

A

into blood

caused by neurostimuli from hypothalamus > hormone released from granule > down axon terminal > circulation

92
Q

neurosecretion defn

A

how oxytocin/ADH released because their release from herring bodies controlled by neurostimuli

93
Q

where is pineal gland

A

it is a diverticulum of posterior diencephalon, at posterior end of III ventricle

94
Q

what covers pineal gland?

A

pia mater

95
Q

structures of pineal gland?

A

lobules separated by CT septa; neuroglial cells (pinealocytes) inside lobules; corpora arenacea outside

96
Q

corpora arenacea- where and what is it?

A

outside pineal gland
extracellular calcified bodies containing CaPO4, MgPO4, carbonate in an organic matrix
increase with age

97
Q

what controls day/night cycle (diurnal rhythms) of the body?

A

melatonin, “hormone of the darkness”

98
Q

why is melatonin “hormone of the darkness”?

A

synthesis induced by darkness and suppressed by light

99
Q

what is melatonin synthesized from?

A

the amino acid tryptophan, via serotonin

100
Q

what effect does melatonin have on reproduction?

A

has anti-reproductive effects by decreasing gonadotropin (FSH, LH) release

101
Q

relationship between melatonin and jet lag?

A

use of melatonin may help counteract drowsiness, disorientation related to jet lag because helps reacclimate to correct time zone

102
Q

what happens if remove pineal gland from animal?

A

gonadotropin production increases

reproductive organs enlarge

Structures: Part Deux (36 decks)

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