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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
where is pituitary located
beneath floor of III ventricle, connected to hypothalamus
25
where is diencephalon, what does it consist of?
between forebrain and midbrain forms wall of ventricle or cisterna consists of thalamus, hypothalamus, epithalamus
26
which part of thalamus and of hypothalamus forms floor of III ventricle?
ventral part of thalamus | median eminence of hypothalamus
27
where does floor of III ventricle extend into?
site of pituitary gland
28
why is pituitary gland "master" gland?
although tiny, it controls most of endocrine functions of the body
29
where does pituitary gland sit?
in hypophyseal fossa, a bony depression of the sella turcia (hump) of the sphenoid bone (in middle cranial fossa)
30
where is median eminence of hypothalamus, what does it connect to?
between/just posterior to optic chiasma | connects by stalk to pituitary gland
31
2 parts of pituitary gland
1) adenohypophysis, anterior pituitary, aka pars distalis - glandular 2) neurohypophysis, posterior pituitary, aka pars nervosa
32
pars distalis means
hormones of anterior pituitary
33
pars distalis contains
most endocrine cells of pituitary
34
pars nervosa means
hormones of posterior pituitary
35
parts of anterior pituitary
1) pars distalis 2) pars tuberalis 3) pars intermedia
36
parts of posterior pituitary
1) pars nervosa 2) infundiibulum 3) median eminence
37
what does posterior pituitary (neurohypophysis) develop from
nervous tissue of hypothalamus
39
what does anterior pituitary (adenohypophysis) develop from
ectoderm of roof of the mouth
40
how does pituitary gland develop?
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
41
what does pars nervosa develop from?
distal end of hypothalamus
42
what does rathke's pouch become?
anterior part: anterior part of pars distalis | posterior part: pars intermedia
43
where does rathke's pouch develop from?
roof of the mouth
44
what is between pars nervosa and pars distalis?
pars intermedia
45
how/where does pituitary gland connect to the hypothalamus?
pars nervosa connects to stalk to hypothalamus | functional and physical connection
46
how/why do pars nervosa and pars distalis stain differently?
pars distalis stains darker b/c has endocrine cells
47
characteristics of pars distalis
1) endocrine cell clusters 2) reticular fibers, Type III collagen, support 3) FENESTRATED/SINUSOIDAL CAPILLARIES throughout for rapid diffusion of hormones into circulation
48
chromophils
affinity for dye 1) acidophils- affinity for acidic dye 2) basophils- affinity for basic dyes
49
chromophobes
degranulated acidophils/basophils, granules don't stain by antibodies
50
how many populations/types of endocrine cells are there
5
51
how would you localize endocrine hormones
immunocytochemical staining | make an antibody against a hormone, localize it
52
why 6 hormones but 5 cell types
because both FSH and LH expressed by 1 cell type, gonadotrophs
53
6 hormones localizable with immunocytochemical staining
growth hormone, prolactin, corticotropin (ACTH), thyrotropin (TSH), follicle stimulating hormone (FSH), luteinizing hormone (LH)
54
how can you tell anterior pituitary cell in EM?
anterior pituitary hormones are stored in granules, which has marker that stains positively
55
how are endocrine cell types named?
for the hormones they secrete
56
acidophils of pars distalis?
1) somatotrophs | 2) mammatrophs
57
what do somatotrophs secrete, what proportion is this of all pars distalis?
``` growth hormone (GH) 50% ```
58
what do mammatrophs secrete, what proportion is this of all pars distalis?
prolactin | 20%
59
basophils of pars distalis?
1) corticotrophs 2) thyrotrophs 3) gonadotrophs
60
what do corticotrophs secrete, what proportion is this of all pars distalis?
corticotropin (ACTH) | 20%
61
what do thyrotrophs secrete, what proportion is this of all pars distalis?
thyrotropin (TSH) | 5%
62
what do gonadotrophs secrete, what proportion is this of all pars distalis?
1) follicle stimulating hormone (FSH) 2) luteinizing hormone (LH) 5%
63
how are pars distalis hormones controlled?
secretion of pars distalis hormones controlled by HYPOTHALAMUS via HYPOTHALAMIC RELEASING or INHIBITING HORMONES
64
function of hypophyseal (pituitary) portal system?
in pituitary gland | provides anatomical-function link between hypothalamus & pars distalis of anteiror pituitary
65
blood supply to pituitary gland?
inferior & superior hypophyseal artery - branchs of coratid
66
how does hypophyseal portal system work
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
what do neurosecretory cells in hypothalamus do?
control pars distalis hormone secretion by making releasing and inhibiting hormones
68
what do releasing and inhibiting hormones of hypothalamus neurosecretory cells target?
anterior pituitary hormones | therefore effect target organ cells
69
what are the hypothalamic hormones?
1) GH-releasing hormone 2) corticotropin-releasing hormone 3) TSH-releasing hormone 4) gonadotropin-releasing hormone 5) dopamine 6) somatostatin
70
GH-releasing hormone function?
stimulates GH release
71
corticotropin-releasing hormone function?
stimulates ACTH release
72
TSH-releasing hormone function?
stimulates TSH release
73
gonadotropin-releasing hormone function?
stimulates FSH and LH release
74
dopamine function?
INHIBITS prolactin release - unique b/c inhibition!
75
somatostatin function?
aka global inhibitor - always inhibits, wherever it acts INHIBITS GH release ex: inhibits glucose release in pancreas
76
when is pars intermedia well pronounced?
in animals, not in humans
77
what does pars intermedia secrete
2 types of melanocyte-stimulating hormone: B-MSH: skin pigmentation A-MSH: anti-appetite
78
what are melanocyte-stimulating hormones product of?
pro-opiomelanocortin (POMC)
79
what do pars intermedia granules and corticotrophs both synthesize
pro-opiomelanocortin
80
what can pro-opiomelanocortin split into
1) ACTH 2) lipotropins for lipid metabolism 3) endorphins for endogenous opioids 4) MSHs B and A for skin pigmentation and anti-appetite
81
what hormones does pars nervosa secrete
1) antidiuretic hormone (ADH; vasopressin) | 2) oxytocin
82
what do pars nervosa hormones bind to
a carry protein neurphysin
83
what produces ADH?
neurons in the supraoptic nuclei of the hypothalamus
84
what produces oxytocin?
neurons in the paraventricular nuclei of the hypothalamus
85
what is the hypothalamohypophyseal tract
axon tract that carries hormones (ADH, oxytocin) from neuron of hypothalamus to pars nervosa of pituitary
86
ADH function?
water absorption in collecting ducts, convoluted tubules of kidneys
87
oxytocin functions?
1) acts on myoepithelial contraction- physically expelling milk from mammary glands 2) uterine contraction
88
what are pituicytes?
neuroglia - supporting cells of hypothalamo-hypophyseal tract
89
what is hypothalamo-hypophyseal tract made of
100,000 unmyelinated axons
90
what are herring bodies
swellings along axon of hypothalamo-hypophyseal tract; collecting sites of granules of hormones ADH and oxytocin, which bind in herring bodies to neurophysin
91
what controls release of ADH/oxytocin, where are they released?
into blood | caused by neurostimuli from hypothalamus > hormone released from granule > down axon terminal > circulation
92
neurosecretion defn
how oxytocin/ADH released because their release from herring bodies controlled by neurostimuli
93
where is pineal gland
it is a diverticulum of posterior diencephalon, at posterior end of III ventricle
94
what covers pineal gland?
pia mater
95
structures of pineal gland?
lobules separated by CT septa; neuroglial cells (pinealocytes) inside lobules; corpora arenacea outside
96
corpora arenacea- where and what is it?
outside pineal gland extracellular calcified bodies containing CaPO4, MgPO4, carbonate in an organic matrix increase with age
97
what controls day/night cycle (diurnal rhythms) of the body?
melatonin, "hormone of the darkness"
98
why is melatonin "hormone of the darkness"?
synthesis induced by darkness and suppressed by light
99
what is melatonin synthesized from?
the amino acid tryptophan, via serotonin
100
what effect does melatonin have on reproduction?
has anti-reproductive effects by decreasing gonadotropin (FSH, LH) release
101
relationship between melatonin and jet lag?
use of melatonin may help counteract drowsiness, disorientation related to jet lag because helps reacclimate to correct time zone
102
what happens if remove pineal gland from animal?
gonadotropin production increases | reproductive organs enlarge

Structures: Part Deux (36 decks)

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