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Systemics- Repro and Endocrine > Endocrine > Flashcards

Endocrine Flashcards

1
Q

What is emiocytosis vs exocytosis

A

Secretion of entire secretory granules into extracellular space vs fusion of granules with cell membrane

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2
Q

What hormone types utilize secretory granules?

A

Polypeptide and catecholamine-secreting endocrine cells only

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3
Q

Features of polypeptide producing endocrine cells

A

ER with ribosomes, prominent golgi, secretory granules

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4
Q

Features of steroid producing endocrine cells

A

Large lipid vacuoles that contain cholesterol esters and other precursors, smooth ER, large mitochondria with cytochrome p450 systems
*Lack secretory granules, don’t store product

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5
Q

How do peptide hormones signal? steroids?

A

Peptides- GPCR (cell membrane)
Steroids- lipid soluble, travel through membrane and bind receptors in cytoplasm, travel to nucleus

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6
Q

Half life of peptide vs steroid hormones

A

Short vs long

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7
Q

Features of catecholamines and iodothyronine hormones

A

Tyrosine derivatives
Catecholamines from adrenal medulla, iodothyronines from follicular cells of thyroid
Catecholamines act like polypeptide hormones
Iodothyronines act like steroid hormones

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8
Q

Mechanism of humoral hypercalcemia of malignancy

A

Cancer cells produce PTHrp, which activates PTH receptors in bone and kidney, producing hypercalcemia

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9
Q

Common tumors that cause humoral hypercalcemia of malignancy

A

T cell lymphoma
AGASACA

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10
Q

Clin path findings with HHM

A

Hypercalcemia
Hypophosphatemia
Hypercalciuria
Osteoclastic bone resorption

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11
Q

How do NWPs differ in their vitamin D requirements

A

Require higher levels of vitamin D3, so prone to Vit D Resistant Rickets (type II) and osteomalacia

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12
Q

Causes of prolonged gestation in ruminants

A

Guernsey and Jersey cattle- adenohypophyseal aplasia causes hypoplasia of target organs (Adrenal cortex, thyroid follicular cells, gonads)
Ewes ingesting veratrum californicum- CNS malformations, so no hypothalamic stimulus for pituitary

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13
Q

Types of cells in the pituitary following Pit1 action and GATA2 expression

A

Somatrophs- GH
Lactotrophs- Prolactin
Thyrotrophs- TSH

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14
Q

Type of cells in the pituitary that are Pit1 independent, via Tbx19 and Sf1

A

Corticotrophs- POMC –> ACTH
Melanotrophs- POMC –> MSH
Gonadotrophs- LH/FSH

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15
Q

What cells in the pituitary are acidophilic?

A

Somatotrophs
Lactotrophs

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16
Q

What cells in the pituitary are basophilic? Additional positive stain?

A

Gonadotrophs
Thyrotrophs

PAS

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17
Q

What cells do not have obvious secretory granules (are not acidophilic or basophilic)

A

Chromophobes- corticotrophs and melanotrophs

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18
Q

What does the neurohypophysis do?

A

Contains terminal, unmyelinated axons from neurosecretory neurons from the hypothalamus that secrete oxytocin and ADH

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19
Q

Who is most likely to get juvenile pan hypopituitarism; associated genetic defect in dogs

A

Dogs- GSD, Spitz, Toy Pinscher, Wolfdogs
Eurasian badger; LHX3 gene, autosomal recessive

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20
Q

Which hormones are deficient in panhypopituitarism? Which are not?

A

GH, TSH, prolactin, gonadotropins; ACTH normal maybe

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21
Q

Remnant of distal craniopharyngeal duct- location and who gets it

A

Brachycephalic dogs, periphery of pars tuberalis and distalis

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22
Q

Remnant of proximal craniopharyngeal duct- location and who gets it

A

Brachycephalic dogs, dorsal oral cavity/nasopharynx

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23
Q

Rathke’s pouch ectoderm differentiation failure- location and who gets it

A

Entire pars distalis replaced, causes pituitary dwarfism in GSDs

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24
Q

Most common cause of Cushing’s

A

Corticotroph pituitary adenoma in pars distalis or pars intermedia

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25
Cause of clinical signs in Cushing's
Hyperplasia of adrenal cortices and chronically high cortisol
26
Which zones are hyperplastic in Cushing's?
Zona fasciculata and reticularis
27
Who gets adenomas of the pars distalis? Pars intermedia?
Brachycephalic; nonbrachycephalic
28
Difference between adenomas of pars intermedia and pars distalis?
Intermedia has numerous colloid-filled follicles between neoplastic cells
29
Most common pituitary tumor in the horse? Clinical syndrome?
Pars intermedia adenoma; Pituitary pars intermedia dysfunction
30
Who gets PPID more?
Females, older
31
Key histo with equine pars intermedia adenoma
Spindle to polygonal eosinophilic cells; Follicles lined by cuboidal cells with colloid
32
Clinical signs with PPID; pathogenesis?
PU/PD, hirsutism, hyperhidrosis, laminitis; Most signs due to compression of hypothalamus, also elevated POMC and MSH, CLIP, beta endorphin
33
Most common pituitary tumor in cats; predisposes to
Somatotroph; acromegaly, diabetes mellitus
34
Most common pituitary tumor in rats
Lactotroph
35
What pituitary tumor do budgies get?
Somatotroph
36
Where is the adrenal cortex derived from? Medulla?
Mesoderm; neural crest ectoderm
37
Role of zona glomerulosa, fasciculata, and reticularis
G- Mineralocorticoids, columns F- Glucocorticoids, abundant lipid, most of cortex (70%) R- Sex steroids
38
Effects of glucocorticoids
Sparing of glucose, hyperglycemia, increased gluconeogenesis Suppress inflammation and immune system Phagocyte inhibition Stability of lysosomal membranes Decreased wound healing
39
Renin-angiotensin system summary
Renin produced by juxtaglomerular apparatus, cleaves angiotensinogen to angiotensin I, which is then converted to angiotensin II Angiotensin II is a vasoconstrictor and trophic for glomerulosa, increasing aldosterone
40
What does ACTH do?
Stimulates Fasciculata and reticularis through melanocortin 2 receptors (adenylyl cyclase and cAMP)
41
Difference between idiopathic adrenocortical atrophy and trophic atrophy secondary to pituitary lesion with decrease in ACTH stimulation?
Idiopathic adrenocortical atrophy affects all layers of cortex, whereas trophic atrophy only affects inner two layers of cortex, so no electrolyte disturbances
42
Layers affected by nodular hyperplasia of adrenal cortex
G and F
43
Layers affected by diffuse adrenal cortical hyperplasia; cause?
Corticotroph adenoma, causes hyperplasia of Fasciculata and reticularis
44
Associated lesion with adrenal cortical carcinoma; most common in who?
Extension into caudal vena cava; Cattle*, occurs in dogs but adenoma more common
45
Most common adrenal tumor in ferrets
Cortical carcinoma, usually in left adrenal
46
Clinical signs with ferret adrenal tumor; pathogenesis
PU/PD, vulvar enlargement, alopecia; overproduction of estrogenic steroids (estradiol-17beta)
47
Associated lesion in ferrets with adrenal tumors
Insulin-producing islet cell tumors
48
Predisposing factors for ferret adrenal tumors
Female, early gonadectomy (elevated LH secretion due to lack of negative feedback)
49
Role of adrenal medulla; IHCs for medulla
Synthesis of catecholamines- NE and Ep; Chromogranin A
50
Catecholamine pathway
Tyrosine-->Dopamine-->norepinephrine-->epinephrine
51
Tumor that commonly accompanies pheochromocytoma
C cell thyroid adenoma
52
Key histo with pheochromocytoma
Fine granular cytoplasm, neuroendocrine appearance, muddy brown cytoplasm
53
Clinical signs with pheochromocytoma
Tachycardia, edema, cardiac hypertrophy, arteriolar sclerosis and medial hyperplasia
54
Apicomplexan that commonly localizes to adrenal cortex
Toxoplasma gondii
55
How is PTH regulated? Role of phosphorus?
When blood Ca is high, PTH release inhibited, when low, PTH released; Hyperphosphatemia decreases Ca, stimulating parathyroids
56
Major inhibitors of PTH synthesis and release?
Calcium and calcitriol
57
Actions of PTH
Stimulate calcitriol production in kidney Increase reabsorption of Ca in kidney, and excretion of phosphorus Mobilize Ca (and phos) from bone Upregulates RANKL on osteoblasts (stimulate differentiation of osteoclasts)
58
RANKL is on which cell? RANK is on which cell? Osteoprotegerin is what?
Osteoblasts; osteoclasts; soluble decoy receptor to regulate resorption
59
Vitamin D activation pathway
Cholecalciferol from diet and skin-->In hepatocyte ER, cholecalciferol-25-hydroxylase converts to 25-hydroxycholecalciferol--> in kidney PCT mitochondria, 1 alpha hydroxylase converts to calcitriol (rate-limiting)
60
PTH role in vitamin D activation
PTH stimulates 1 alpha hydroxylase, increasing production of calcitriol
61
What other factors influence calcitriol?
Phosphate- inhibits 1 alpha hydroxylase FGF23 inhibits 1 alpha hydroxylase
62
Calcitriol's main role; how
Increase absorption of Ca and phosphate from intestine; increases calcium binding protein on luminal enterocyte
63
Other roles of calcitriol (in bone)
Upregulates RANKL on osteoblasts (stimulating differentiation of osteoclasts) Stimulates release of FGF23 by osteocytes
64
Roles of FGF23
Inhibits 1 alpha hydroxylase Inhibits PTH secretion Increases renal phosphate excretion
65
Calcitonin's role in Ca regulation; what stimulates its release?
Lowers plasma Ca; concentration of Ca in plasma and ECF stimulates C cells (same receptor as Chief cells)
66
What causes C cell hyperplasia?
Long-standing hypercalcemia
67
Actions of calcitonin
Inhibit osteoclastic bone resorption Prevents postprandial hypercalcemia and excessive loss during pregnancy
68
What causes diffuse parathyroid hyperplasia?
Chronic renal failure, dietary imbalances
69
Key histo with parathyroid adenoma; who is predisposed?
Karyomegaly and anisokaryosis, fibrous capsule, compressed rim of normal tissue; keeshonds
70
Associated lesion with primary hyperparathyroidism
Hyperostotic fibrous osteodystrophy
71
Where does thyroid carcinoma often metastasize to first?
Pulmonary, then lymph nodes, because drains directly into brachiocephalic trunk
72
Thyroid hormone synthesis pathway
Tyrosine-->incorporated into thyroglobulin protein-->thyroperoxidase oxidizes iodide into iodine--> iodine bound to tyrosine-->thyroxine (T4) and triiodothyronine (T3)
73
How is iodine transported to follicular lumen?
Cotransported into follicular cell as iodide via NIS, then passively transported via pendrin into lumen
74
What happens to follicles with sustained TSH?
Follicular cells become more columnar, lumina become smaller, increased endocytosis of colloid
75
What happens to follicles with decreased TSH?
Follicular cells become flattened/cuboidal, follicles become enlarged and distended, decreased endocytosis of colloid
76
Most common two causes of hypothyroidism in dogs
Lymphocytic thyroiditis and idiopathic follicular collapse
77
What causes lymphocytic thyroiditis?
Autoantibodies against thyroglobulin, thyroperoxidase, the TSH receptor, or other
78
How does excess iodide cause goiter?
Interferes with fusion of lysosomes and colloid droplets
79
Plants that cause goiter; toxic principle?
White clover (trifolium) Couch grass (cynoden) Linseed meal Brassica; Goitrin inhibits organification of iodine
80
Cats with hyperthyroidism often have what concurrent histo finding?
Diffuse chief cell hypertrophy and hyperplasia in the parathyroid
81
Most common type of thyroid adenoma?
Follicular adenoma
82
Most common thyroid tumor in the dog? Cat?
Follicular cell carcinoma; adenoma
83
Breeds predisposed to thyroid carcinoma
Beagles, boxers, huskies, goldens
84
Who gets C cell (parafollicular) thyroid tumors?
Guernsey Bulls and rats get carcinomas, most common thyroid tumor in horses
85
Key histo with C cell carcinoma
Amyloid (A Cal), neuroendocrine appearance
86
What is a predisposing factor to C cell tumors, especially in which species?
High calcium diets; cattle
87
Who is predisposed to pheochromocytomas?
Clouded leopards
88
Diagnostic test on necropsy floor for pheochromocytomas?
Zenkers solution- turn brown-yellow
89
TEM of pheochromocytomas
Wonky granules with wide submembranous space- NE Less dense core with narrow submembranous space- Epinephrine
90
Key histo with chemodectoma?
Variable numbers of karyomegalic or hypertrophied giant cells; positive for chromogranin A and Churukian Schenk
91
Difference between pheochromocytoma and chemodectoma?
Pheochromocytoma is derived from chromaffin cells Chemodectoma is derived from nonchromaffin, extraadrenal paraganglia, no chromaffin granules
92
Which chemodectoma has the worst prognosis? Who is predisposed?
Carotid body tumors; brachycephalic breeds (chronic hypoxia)
93
Predominant exocrine stimulus; inhibitors?
Insulin; glucagon, somatostatin
94
Role of insulin
decreases serum glucose by stimulating uptake and glycogenesis, anabolic effects, cell growth
95
Role of glucagon
Promotes glycogenolysis, gluconeogenesis, lipolysis
96
What inhibits glucagon release?
Amylin (co-secreted with insulin) and somatostatin
97
Role of somatostatin
Inhibits release of glucagon, insulin, pancreatic polypeptide (regulates magnitude of responses)
98
Species differences in distribution of islets
Dogs- more in tail Cats- large irregular shape Ruminants- large and small islets
99
Cause of islet amyloidosis in cats
Associated with diabetes- may be pre-diabetic, caused by IAPP (amylin)
100
Islet amyloid with potassium permanganate
Retains congophilia
101
What is islet inflammation associated with in rats?
lymphocytic thyroiditis
102
What are glucagonomas associated with in dogs?
Superficial necrolytic dermatitis

Systemics- Repro and Endocrine (3 decks)

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