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Describe the blood supply to the adrenal gland.
small arteries penetrate the capsule; they are sinusoidal and bathe the cells in blood
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______________ nerve fibers synapse on ___________ of the adrenal medulla.
Preganglionic myelinated sympathetic; secretory cells
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Exogenous cortisol causes ___________ of the __(2)__.
trophic atrophy; zona fasiculata and reticularis
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Treatment with glucocorticoids reduces...
endogenous ACTH and glucocorticoid production.
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Exogenous corticosteroids inhibit __________; long term use leads to lesions in the adrenal that include increased ________ because...
ACTH secretion; lipid; ACTH is necessary to convert cholesterol to glucocorticoids.
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2 metabolic syndromes associated with atrophy of the adrenal cortex.
peracute- Waterhouse-Fredrickson Syndrome, chronic- Addison's Disease
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Why do we not often diagnose and treat peracute adrenocortical insufficiency?
very high mortality- patients (usually young animals) die quickly
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What are causes of peracute adrenocortical insufficiency (Waterhouse-Fredrickson Syndrome)? (4)
diffuse cortical necrosis/hemorrhage (trauma/septicemia), thrombosis of adrenal vessels, toxemia
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Chronic hypoadrenocorticism causes loss of _________.
all 3 layers of the cortex
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What is the most common cause of chronic hypoadrenocorticism? What are 2 less common causes?
inflammation (adrenalitis); less commonly: necrosis, mineralization of adrenal cortex
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Why is the adrenal so sensitive to fungal and protozoal insults?
high levels of glucocorticoids, which are immunosuppressive
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Addison's disease is caused by ____________ that is comprised of ___________, causing secondary __(2)__.
idiopathic autoimmune adrenalitis; lymphoplasmacytic inflammation; atrophy and fibrosis
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How does autoimmune adrenalitis affect the pituitary gland?
pituitary corticotroph hyperplasia because it is trying to stimulate the adrenal (which isn't functioning)
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Patients with Addison's have _______ ACTH and ________ glucocorticoids.
high; low
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Sub-clinical, age-related change in the adrenal cortex of dogs.
extracoritcal nodular hyperplasia
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Sub-clinical, nodular adrenal change with a variable zone of origin.
multinodular hyperplasia
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__________ animals have lower glucocorticoid stimulation because of...
Older; normal degeneration and mineralization of the adrenal cortex that is associated with age.
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Degeneration and mineralization of the adrenal cortex with age usually affects the __(2)__.
zona fasiculata and reticularis
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Functional adenomas of the adrenal cortex can cause... (2)
hyperadrenocorticism, hyperestrogenism (ferrets)
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Carcinomas of the adrenal cortex invade the ________, and ultimately _________.
blood vessels (esp. the vena cava); metastasize
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How can you identify a functional tumor of the adrenal cortex on necropsy?
the rest of the cortex/contralateral adrenal is atrophied (trophic atrophy- tumor is secreting all the hormone)
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Almost all ferrets are gonadectomized at a young age; this leads to increased levels of _______ and secondarily increased __(2)__; in ferrets, this stimulates the adrenal cortex, and the tumor the develops produces _________.
GnRH; LH and FSH; estrogen
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How can you differentiate adrenal cortex hyperplasia from tumors in ferrets?
hyperplasia is bilateral; tumors are unilateral
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What are clinical signs of hyperestrogenism in ferrets? (2)
vulvular enlargement, bilaterally symmetrical alopecia of abdomen and rear legs
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In ferrets, hyperestrogenism causes... (4)
anemia, thrombocytopenia, pyometra, prostate enlargement
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Ferrets with hyperestrogenism get pyometra secondary to ___________.
endometrial hyperplasia
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The adrenal medulla derived from __________ from __________.
neuroectoderm; neural crest
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Why do neural crest cell migrate ventrally to form the adrenal medulla?
the adrenal cortex has glucocorticoids--> chromaffin cells of the medulla want to be in an environment of high glucocorticoid conc
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Hormones of the adrenal medulla.
catecholamines- epinephrine and norepinephrine
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Describe the gross appearance of the adrenal cortex and medulla and why they appear this way.
- cortex- fatty- lipid is precursor for corticosteroids
- medulla- darker- uses AAs as precursors for catecholamines
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What are the contents of the adrenal medulla secretory granules? (5)
catecholamines, ATP, chromogranin A, Dopamine beta-hydroxylase, ascorbate
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What component of the adrenal medulla secretory granules is used as a diagnostic tool for endocrine tumors? What is a con to using this tool?
Chromogranin A- does not localize the tumor to a specific endocrine organ (adrenal, parathyroid, etc)
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Enzyme that converts NE to Epi; only present in epinephrine-producing cells.
phenylethanolamine N-methyl transferase (PNMT)
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The enzyme PMNT is induced by _________.
cortisol
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Clinically, which catecholamine is more potent?
epinephrine
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Biologically, which catecholamine has a greater effect on end organs in the body?
norepinephrine
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Response of an organ to sympathomimetic amines depends upon the...
proportion and density of alpha and beta receptors.
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Effects of NE on the body. (3)
generalized vasoconstriction,pupillary dilation, decreased GI motility
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Effects of Epi on the body. (5)
selective vasoconstriction of skin and kidney, selective vasodilation of skeletal m. and coronary aa., increased cardiac activity, increased metabolism, bronchiolar dilation
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What organs does Epi vasoconstrict? Which ones does it vasodilate?
- Vasoconstriction- organs not necessary for fleeing danger (skin, kidneys)
- Vasodilation- organs necessary for flight (skeletal muscle, coronary aa.)
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What effects does Epi have on metabolism? (4)
increase basal metabolic rate, glycogenolysis, lipolysis, increased blood glucose
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The adrenal medulla provides _________ response to stress; the adrenal cortex provides _________ response to stress.
rapid, short-term; long-term
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How are catecholamines recycled locally?
local nerve ending- enzymatic degradation, physical diffusion, re-uptake into nerves
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How are catecholamines recycled systemically?
enzymatic degradation in the liver
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What happens with absence of the adrenal medulla?
not essential for life- may not react as quickly to stressful situations (oh well...)
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Why must the adrenal medulla be examined soon after death to be a reliable indicator of disease?
undergoes rapid post-mortem autolysis (may over-diagnose hemorrhage and necrosis)
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4 types of adrenal medullary hyperfunction/neoplasms.
hyperplasia, neuroblastoma, ganglioneuroma, pheochromocytoma
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Hyperplasia of the adrenal medulla occurs in __(2)__ due to _________.
rats and cows; chronic stress
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Proliferative, aggressive, malignant tumor of the adrenal medulla that occurs in young animals; consists of poorly differentiated round cells.
neuroblastoma
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Benign tumor of the adrenal medulla; composed of neurons and axons.
ganglioneuroma
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Tumor of secretory cells of the adrenal medulla that may start as hyperplasia and progresses to a benign space-occupying mass, and sometimes to a malignant tumor.
Pheochromocytoma
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Malignant pheochromocytoma invades the _________.
caudal vena cava
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Tumor that appears in the adrenal medulla in animals that are especially susceptible to endocrine neoplasia.
multiple endocrine neoplasia (MEN)
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Functional effects of neoplasms in the adrenal medulla. (4)
space-occupying mass, hormone secretion, vascular invasion, necrosis and hemorrhage
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Effects of hormone-secreting adrenal tumors. (5)
tachycardia, hypertension, sweating, hyperglycemia, vasoconstriction
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Describe the Chromaffin reaction.
used to differentiate cortical and medullary neoplasms- brown staining means medullary neoplasm
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Metastatic neoplasms from other Morgans that end up in the adrenal medulla are usually __________; this is more/less common than to the adrenal cortex.
bilateral; more
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Neoplasms in cats and cows that metastasize to the adrenal medulla.
lymphoma
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Neoplasms in dogs that metastasize to the adrenal medulla.
lung, mammary, prostate
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