Pathology of Endocrine System Flashcards
What is the function of the endocrine system?
to secrete product (hormone) into the blood stream
Generally, what is secretion in the endocrine system controlled by?
feedback mechanisms
What hormone types are excreted by the endocrine system?
protein and peptides, amino acid derivatives, and steroid and fatty acid derivatives
What do protein and peptide derivatives bind to?
target cell surface receptors
What parts of the endocrine system secrete protein and peptide hormones?
pituitary, parathyroid, C-cells, and islets of Langerhans
What parts of the endocrine system secrete amino acid derivatives?
adrenal medulla and thyroid
What do steroid and fatty acid derivative hormones bind to?
target cell cytoplasmic receptors
What part of the endocrine system secretes steroid and fatty acid derivative hormones?
adrenal cortex
What are some productive lesions of the endocrine organs?
hyperplasia and neoplasia
What are some destructive lesions of the endocrine organs?
hypoplasia, atrophy, inflammation, necrosis, amyloidosis, surgical misadventure, and neoplasia
When is hyperplasia of endocrine organs functional?
increased trophic stimulus
When is hyperplasia of endocrine organs nonfunctional?
aging
What is atrophy of endocrine organs caused by?
decrease in trophic stimulus, inflammation, and necrosis
Clinically significant endocrine disease is due to what?
an increase or a decrease in hormone function
What are the types of hyperfunction?
primary or secondary hyperfunction
What is primary hyperfunction?
uncontrolled increase in hormone production
What is secondary hyperfunction?
increase in hormone production due to increase in trophic stimulus
Hyperfunction causes what?
decreased breakdown, production of hormone-like molecules, and lactogenic/exogenous intake
What are the types of hypofunction?
primary and secondary
What is primary hypofunction?
decrease in hormone production due to destriction of a gland
What is secondary hypofunction?
decreased hormone production due to decrease in trophic stimulus
What are some lesions of endocrine diseases in non-endocrine tissues?
epidermal atrophy, bilaterally symmetrical alopecia, hepatic lipidosis, soft tissue mineralization, artherosclerosis, muscle atrophy, cataract, and PU/PD
What is the adenohypophysis?
the anterior pituitary
What is the adenohypophysis derived from?
oral ectoderm (Rathke’s pouch)
What are the parts of the adenohypophysis?
pars distalis, pars intermedia, amd pars tuberalis
What does the pars distalis produce?
acidophils, basophils, and chromophobes
What hormones are the acidophils?
GH, prolactin, ACTH
What hormones are the basophils?
FSH, LH, TSH
What hormones are chromophobes?
pro-opiomelanocortin which is cleaved into ACTH, MSH, and beta-endorphin)
What is the pars distalis stimulated by?
releasing factors from the hypothalamus
What is the pars distalis down regulated by?
increase in blood hormone from the target gland
Where is the pars intermedia located?
adjacent to the pars nervosa
What does the pars intermedia secrete?
chromophobes (POMC)
What is chromophobe secretion from the pars intermedia down regulated by?
an increase in dopamine
What does the pars tuberalis surround?
the hypophyseal stalk
What is the neurohypophysis?
the posterior pituitary
What is the neurohypophysis derived from?
the neuroectoderm
What is the pars nervosa?
part of the neurohypophysis that contains axons from neurons in hypothalamic nuclei
What nuclei are in the pars nervosa?
supraoptic nucleus and paraventricular nucleus
What does the supraoptic nucleus produce?
ADH
What does the paraventricular nucleus produce?
oxytocin
What lesions are associated with the pituitary gland?
aplasia, hypoplasia, abscess, neoplasms of adenohypophysis
What are neoplasms of the adenohypophysis usually?
chromophobe; adenoma or carcinoma
Are neoplasms of the adenohyophysis functional or nonfunctional?
they can be both
What hormones are associated with functional neoplasms of the adenohyophysis?
ACTH and GH
What does increased ACTH due to a functional neoplasm of the adenohypophysis cause?
adrenal cortical hyperplasia which causes hypercortisolism
What does increased GH due to a functional neoplasm of the adenohyophysis cause?
gigantism, acromegaly, and refractory DM in cats
What generally do expansion neoplasms of the adenohypophysis cause?
compresses/destroys adjacent parenchyma
What hormones are associated with expansion neoplasms in adenohypophysis?
ADH and TSH
What does decreased ADH cause?
diabetes insipidus
What deos decreased TSH cause?
thyroid atrophy which leads to hypothyroidism
What clinical syndromes are associated with the pituitary gland?
juvenile panhypopituitarism, equine chromophobe adenoma of Pars Intermedia/Pituitary Pars intermedia dysfunction, and canine chromophobe adenoma
What species does juvenile panhypopituitarism typically affect?
dogs - german shepards
What hormone changes are associated with panhypopituitarism?
decreased GH, ACTH, TSH, FSH, and LH
What lesions are associated with juvenile panhypopituitarism?
stunted, retained puppy hair coat
What hormone changes are associated with equine chromophobe adenoma of pars intermedia/pituitary pars intermedia dysfunction?
+/- increase in ACTH and or increase of POMC
When equine chromophobe adeonma of pars intermedia/pituitary pars intermedia dysfunction expands into the hypothalamus, what happens?
there is impaired ADH production
What lesions are associated with equine chromophobe adenoma of pars intermedia/pituitary pars intermedia dysfunction?
hirsutism, +/- adrenal cortical hyperplasia, hyperhidrosis, lethargy, and PU/PD
What type of neoplasm is canine chromophobe adenoma?
a functional one
What does canine chromophobe adenoma cause?
an increase in ACTH causing diffuse adrenal cortical hyperplasia
Canine chromophobe adenoma causes pituitary - ______ ________.
dependent hyperadrenocorticism
What is the structure of the thyroid gland?
bilobed or 2 glands
What are the follicles of the thyroid gland composed of and what do they produce?
follicular cells - colloid
What does iodinated colloid cause?
T3 and T4 (thyroxine)
What is the thyroid controlled by?
a feedback loop
What is the feedback loop of the thyroid gland?
decrease in T3/T4 to increased TSHrf and increased TSH to follicular hyperplasia and colloid production to increased T3 and T4
What is the thyroid composed of?
capsule, follicular cells, and C-cells
What is the capsule of the thyroid composed of?
reticular connective tissue
What are follicular cells composed of?
single layer cuboidal secetory epithelium and eosinophilic cytoplasm
What are C-cells?
parafollicular cells
Where are c-cells located?
they are polygonal cells between follicles
What do c-cells secrete?
calcitonin
What is the function of calcitonin?
it decreases serum calcium
What lesions are associated with the thyroid gland?
atrophy, enlargement due to hyperplasia, adenomatous hyperplasia, nodular gitre, neoplasms, and lymphocytic thyroiditis
What is enlargement due to hyperplasia also called?
goiter
What is goiter caused by?
iodine deficiency due to goitrogenic plants and chemicals
What species does adenomatous hyperplasia effect?
old cats
What does adenomatous hyperplasia of the thyroid cause?
hyperthyroidism
What neoplasms are associated with the thyroid gland?
adenoma or carcinoma
What type of disease is lymphocytic thyroiditis?
an autoimmune disease
What does lymphocytic thyroiditis result in?
atrophy which causes hypothyroidism
What clinical syndromes are associated with the thyroid gland?
hypothyroidism and hyperthyroidism
What does dogs are lazy and cats are crazy refer to?
dogs get hypothyroidism (weight gain) and cats get hyperthyroidism (weight loss)
What does hypothyroidism cause in the thyroid?
atrophy
What clinical signs are associated with hypothyroidism?
BS alopecia, epidermal atrophy, myxedema, obesity, lethargy, arthersclerosis, and hypercholesterolemia
What other animals does hypothyroidism affect?
horses, sheep, and goats
What does hypothyroidism in horses, sheep, and goats cause?
hyperplastic goitre
What clinical signs are associated with hypothyroidism in horses, sheep, and goats?
mandibular prognathism, BS alopecia, epidermal atrophy, and myxedema
What does hyperthyroidism cause in cats?
adenomatous hyperplasia
What clinical signs does hyperthyroidism cause in cats?
hyperactivits, hunger, tachycardia, hypertrophic CM
What is hyperthyroidism known as in humans?
Grave’s disease
What happens in Grave’s disease?
TSH receptor antibody which mimics TSH which causes hyperplasia
What lesions are associateed with C-cells?
atrophy, hyperplasia, and neoplasia
What does atrophy of C-cells happen in response to?
persistent hypocalcemia
What does hyperplasia of C-cells happen in response to?
persistent hypercalcemia
What neoplasm is associated with c-cells?
thyroid medulalry carcinoma
Where are the adrenal glands located?
retroperitoneally, adjacent to the kidneys
What are the regions of the adrenal gland?
cortex and medulla
What is the capsule of the adrenal gland made up of?
reticular connective tissue
What is the capsule of the adrenal gland adjacent to?
autonomic ganglia
What is the cortex of the adrenal gland derived from?
cholesterol - mesoderm
What are hormones are associated with the cortex of the adrenal glands?
mineral corticoids, glucocorticoids, and androgens
What is the medulla of the adrenal glands derived from?
catecholamines - neural crest
What hormones are associated with the medulla of the adrenal glands?
epinephrine and norepinephrine
What are the layers of the adrenal cortex?
zona glomerulosa, zona fasiculata, and zona reticularis
Which layer of the adrenal cortex is the superficial layer?
zona glomerulosa
What is the histological structure of the zona glomerulosa?
columnar cells aligned in arching cords
What does the zona glomerulosa do?
it produces aldosterone in response to angiotensin II which increases Na resorption and increases potassium excretion
What layer of the adrenal cortex is the middle layer?
zona fasiculata
What is the histological structure of the zona fasiculata?
columnar to polygonal cells with small vacuoles
What is the function of zona fasiculata?
produces cortisol in the response to ACTH
What layer of the adrenal cortex is the inner layer?
zona reticularis
What is the histologial structure of zona reticularis?
polygonal cells with small vacuoles
What does zona reticularis do?
produces androgens (and estrogens in some animals)
What regulates the adrenal medulla?
the sympathetic nervous system
What does the adrenal medulla release?
epinephrine and norepinephrine from preformed granules
What cell types make up the adrenal medulla?
chromaffin cells and ganglion cells
What is the structure of chromaffin cells in the adrenal medulla?
aligned in cords and clusters on fibrovascular stroma and sinusoids
What do chromaffin cells contain?
epinephrine and norepinephrine in preformed granules
What is the function of ganglion cells in the adrenal medulla?
they receive sympathetic stimuli and cause chromaffin cells to degranulate
What lesions are associated with the adrenal cortex?
diffuse atrophy, hyperplasia, adrenalitis, hemorrhage, necrosis, and neoplasms
What is diffuse atrophy of the adrenal glands caused by?
decreased ACTH, glucocorticoids, OPDDD, secondary to Lc adrenalitis
What is nodular adrenal cortex hyperplasia caused by?
incidental aging change
What is diffuse adrenal cortex hyperplasia caused by?
increased ACTH or idiopathic
What are the types of adrenalitis?
lymphocytic and granulomatous
What is lymphocytic adrenalitis caused by?
autoimmune disease
What is granulomatous adrenalitis caused by?
fungal or mycobacterial infection
What is adrenal cortex hemmorhage caused by?
gram negative sepsis
How does adrenal cortex necorosis present?
diffuse with hemorrhage
What is multifocal adrenal cortex necrosis caused by?
neonatal herpesvirus infections
What neoplasms are associated with the adrenal cortex?
adenoma and carcinoma
What lesions are associated with the adrenal medulla?
neoplasms - pheochromocytoma
What clinical syndromes are associated with the adrenal glands?
canine hyperadrenocorticism, hyperadrenocorticism, and hypoadrenocorticism
What is canine hyperadrenocorticism also known as?
Cushing’s like disease
What causes canine hyperadrenocorticism?
increased cortisol or exogenous glucocorticoid
What are different scenarios/types of canine hyperadrenocorticism?
functional chromophobe tumor, functional adrenal coertical tumor, idiopathicadrenal cortical hyperplasia, and lactogenic glucocorticoid excess
What does functional chromophobe tummor in canine hyperadrenocorticism cause?
an increase in ACTH leading to diffuse adrenal cortical hyperplasia
What does a functional adrenal cortical tumor in canine hyperadrenocorticism lead to?
increased cortisol causing a tumor plus diffuse adrenal cortical atrophy
How does idiopathic adrenal cortical hyperplasia present?
diffuse adrenal cortical hyperplasia
How does lactogenic glucocorticoid excess present?
diffuse adrenal cortical atrophy
What lesions and clinical signs are associated with canine hyperadrenocorticism?
BS alopecia, epidermal atrophy, calcinosis cutis, pot belly, muscle atrophy, hepatomegaly with vacuolar degeneration, and PU/PD
How does hyperadrenocorticism present in ferrets?
diffuse or nodular cortical hyperplasia; cortical adenoma
What hormone changes are associated with hyperadrenocorticism in ferrets?
increased estrogen production
What lesions and clinical signs are associated with hyperadrenocorticism in ferrets?
BS alopecia, epidermal atrophy, feminization, persisten estrus, and pancytopenia leading to hemorrhage
What is another name for hypoadrenocorticism?
Addison’s like disease
What is Addison’s like disease most common in?
dogs - rottweilers
What lesions are associated with Addison’s like disease?
diffuse adrenal cortical atrophy leading to decreased mineralo and glucocorticoids
What is Addison’s like disease secondary to?
adrenalitis or therapy
What clinical signs are associated with Addison’s like disease?
collapse, dehydration, bradycardia, hyperkalemia and hyponatremia
What are the islets of langerhans?
multicell clusters scattered throughout the pancreas
What is the histologic presentation of islets of langerhans?
cuboidal to columnar cells; pale cytoplasm
What cell types make up the Islets of Langerhans?
alpha cells, beta cells, gamma cells, G cells and PP cells
What do alpha cells secrete?
glucagon which increases blood glucose
What do beta cells secrete?
insulin to decrease blood glucose and IAPP which slows gastric emptying and promotes satiety
What do gamma cells secrete?
somatostatin which is an antagonist to GH
What do G cells secrete?
gastrin which increases HCL secretion in the stomach
What do PP cells secrete?
pancreatic polypeptide
What lesions are associated with Islets of Langerhans?
atrophy/loss, vacuolation, lymphocytic isleitis, neoplasms
What is atrophy/loss of Islets of Langerhans?
loss of islets due to inflammation
What is vacuolation of the Islets of Langerhans associated with?
diabetes
What is lymphocytic isletitis associated with?
inflammation
What species is islet amyloidosis seen in?
cats and primates
What neoplasms are associated with Islets of Langerhans?
adenoma and carcinoma
What are the differenttypes of diabetes mellitus?
type I and type II
What causes type I diabetes mellitus?
overt insuline deficiency
What species does type I diabetes mellitus manifest in?
dogs
What occurs to the pancreas in type I diabetes mellitus?
autoimmune isletitis and chornic pancreatitis
What causes type II diabetes mellitus?
insulin antagonism with or without impaired secretion
What species does type II diabetes mellitus typically manifest in?
cats and humans
What is type II diabetes mellitus antagonized by?
cortisol, glucagon, GH, estrogen, IAPP, and obesity
What occurs to the pancreas in type II diabetes mellitus?
ultimate islet exhaustion
What lesions/clinical signs are associated with diabetes mellitus?
hepatic lipidosis, islet vacuolation, cataracts, +/- weight loss, golmerulosclerosis, microangiopathy, islet amyloidosis, persistent hyperglycemia, glucosuria, PU/PD, polyphagia
What species do islet cell neoplasms typically occur in?
dogs and ferrets
What are the types of islet cell neoplasms?
islet cell adenoma, islet cell carcinoma, insulinoma, and gastrinoma
Where do islet cell carcinomas typically metastasize to?
the liver
What do insulinomas cause?
increased insulin secretion leading to hypoglycemia
What do gastrinomas cause?
increased gastrin secretion leading to hyperacidity causing a gastric ulcer
What is the structure of the parathyroid glands?
4 small spherical glands associated with thyroid glands in dogs and cats
What cells are part of parathyroid glands?
chief cells
What do chief cells secrete and what is it regulated by?
parathormone which is regulated by serum ionized calcium
What does parathyroid hormone maintain?
minute to minute control of serum ionized calcium by affecting bone resporption and increased Ca resorption and increased P excretion in the kidney
Parathyroid hormone works in concer with what other nutrient?
vitamin D
What lesions are associated with parathyroid glands?
hypertrophy and hyperplasia, atrophy, lymphocytic parathyroiditis, and neoplasia
What does hypertrophy and hyperplasia of the parathyroid glands cuase?
enlarged glands due to an increased number of chief cells
What does hypertrophy and hyperplasia of the parathyroid respond to?
chronic hypocalcemia by increasing prodction of PTH
What does atrophy of the parathyroid gland respond to?
chronic hypercalcemia or chronic inflammation
Neoplasms of the parathyroid glands are typically _______ and frequently _____.
benign; functional
What clinical syndromes are associated with the parathyroid glands?
hyperparathyroidism, pseudohyperparathyroidism, and hypoparathyroidism
What do both types of hyperparathyroidism result in?
fibrous osteodystrophy
What chemical changes are associated with primary hyperparathyroidism?
functional PTH adenoma causing increased PTH leading to hypercalcemia and fibrous osteodystrophy
What renal chemical changes are associeated with secondary hyperparathyroidism?
chronic renal failure leading to increased P, decreased Ca and D3 causing a chronic Ca drain
What nutritional changes are associated with secondary hyperparathyroidism?
decreased dietary calium and vitamin D or increased dietary phosphorus
What does pseudohyperparathyroidism cause?
production of a PTH-like molecule
What lesions are associated with pseudohyperparathyroidism?
anal sac adenocarcinoma in dogs and lymphosarcoma
What are the causes of hypoparathyroidism?
lymphocytic parathyroiditis, inadvertent surgical removal of the PTH glands, and periparturient hypocalcemia
What causes periparturient hypocalcemia?
decreased serum Ca due to fecal mineralization or lactational demand
What is a specific syndrome associated with hypoparathyroidism in dogs and mares?
eclampsia
What does eclampsia cause?
hyperexcitability and tetany
What is an example of hypoparathyroidism in cows?
milk fever
What does milk fever cause?
paresis leading to paralysis due to decreased Ach release at the neuromuscular junction
What are some additional causative factors of milk fever?
high prepartum dietary Ca, inappatence at parturition, alkalosis causes inhibition of PTH receptors
