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39 Cards in this Set

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What is endocrine signaling?
endocrine glands are collections of specialized cells that synthesize, store and directly release their secretory products into the blood stream in physiological effects on target cells distant from the glands
What do releasing hormones do?
they are produced in the hypothalamus and act on the anterior or the posterior pituitary gland to release trophic hormones which act on specific endocrine glands
stimulating them to release hormones that exert ultimate actions on downstream tissues
What are the components of the anterior pituitary gland?
pars tuberalis
pars intermedia
pars distalis

the pars distalis is the largest portion and is composed of several endocrine cell populations that secrete pituitary hormones
What are the components of the posterior pituitary gland?
infundibular stalk
pars nervosa
How does the pituitary gland develop?
develops from primative mouth cavity (oropharyngeal ectoderm)
Rathke's pouch

Fuses to pars nervosa (outpouching of diencephalon, neuroectoderm)

becomes anterior and posterior pituitary gland
What hormones are secreted from the pars distalis?
ACTH - adrenals (B)
TSH - thyroid (B)
FSH - estrogen/spematogenesis (B)
LH - progesterone/androgen (B)
Prolactin - milk secretion (A)
What hormones are secreted from the pars intermedia?
melanocyte stimulating hormone in humans
What hormones are secreted from the pars tuberalis?
ACTH, FSH, LH
What hormones are secreted from the pars nervosa?
oxytocin
vasopressin
What is the purpose of the infundibular stalk?
bridges the hypothalamic and hypophyseal systems
What does failure of the oropharyngeal ectoderm of Rathke's pouch cause?
pituitary cyst

leads to pituitary dwarfism
juvenile panhypopituitarism
common in German shepherd dogs
What do we see with hyperpituitarism and neoplasms of the adenohypophysis in horses?
hirsutism in horses

with pituitary adenomas of the pars intermedia

horses present with PU/PD, muscle weakness, intermittent fever and hyperhydrosis
What is diabetes insipidus?
disorder of the neurohypophysis

affected animals excrete large amounts of hypotonic urine and are polydipsic

h
What is the hypohyesal form of diabetes insipidus?
central form

any lesion that interferes with ADH synthesis and or secretion

compression and destruction of the pars nervosa, infundibular stalk or suptraoptic nucleus of the hypothalamus
What is the nephrogenic form of diabetes insipidus?
when target cells in the kidney lack the biochemical pathways necessary to respond to ADH

hereditary defects in the ADH receptors ormore rarelt in the aquaporin-2 water channel

Results collecting will not respond to normal or increase circulating levels of ADH
What is hypoadrenocorticism?
-common endocrinopathy in dogs
-signs associated with decrease production of any or all corticosteroids
-lack of mineralcorticoids = severe electrolyte abnormalities such as hyperkalemia
-lack of glucocorticoids leads to decreased gluconeogenesis and increased sensitivity to hypoglycemia
-skin hyperpigmentation may be seen in dogs with longstanting hypoadrenocorticims
-affected dogs have low corticol concentrations and because of severe cortical atrophy do not respond well to exogenous ACTH
What is the cause of necrosuppurative adrenalitis in horse?
actinobacillus equuli
What is hyperadrenocorticism pituitary adenoma?
cushing disease

-one of the most common endocrinopathies in adult or aged dogs
-infrequent in cats and rare in other animals
most commonly associated with -functional corticotroph (ACTH secreting) pituitary adenoma
-functional adrenal gland tumors are only responsible for 10-15% of cushing syndrome cases in dogs

due to interference of the release of ADH see PU/PD in these animals
What is the cause of pendulous abdomen in dogs with hyperadrenocorticism?
hepatomegaly (lipidosis and glycogen deposition)
muscle asthenia and wasting
redistribution of fat
What are the immunosuppresive effects of excess cortisol?
-reduces the expression of inflammatory mediators (cytokines, prostaglandin, NO)
-inhibits the inflammatorty cell migration by inhibiting the expression of cell adhesion moleciles
-promotes apoptosis in leukocytes
-affects wound healing due to inhibition of fibroblast proliferation and collagen synthesis - decrease scar tissue formation
What are the clinical signs of animals with hyperadrenocorticism?
atrophic dermatopathy
alopecia
pendulous abdomen
dermatitis
calcinosis cutis (von kassa stain)
What is calcinosis cutis due to in animals with hyperadrenocorticism?
likely due to the glyconeogenic and protein protein catabolic actions of cortisol which leads to rearrangement of molecular structure of dermal collagen and elastin and to the formation of an organic matrix that attracts and binds calcium
What are additional complications of hyperadrenocorticism?
pulmonary thrombosis

there is a hypercoaguable state characterized by impaired fibrinolysis, increase concentration of coagulation factors and platelet hypersensitivity
What is a pheochromocytoma?
tumors that are seen in cattle and dogs and can develop concurrently with calcitonin secreting thyroid C cell tumors

functional pheochromocytomas are rare but they cause excessive catecholamine secretion may lead to tachycardia, cardiac hypertrophy and hypertension
What are the clinical signs of hypothyroidism?
lethargy, weight gain, heat seeking, low libido, infertility, abortion and anestrus

skin has a non pruritic bilateral alopecia
hyperpigmentation over pressure points
thick facial skin with folding due to accumulation of glycoaminoglycans (myxedema) tragic facial expression

periods of aggression or grumpiness, growling at family members and fighting with other dogs
Cornonary atherosclerosis is often the result of what condition?
hypothyroidism


another possible DDX
Diabetes Mellitus
Cushings (rare)
T/F

Lymphocytic thyroiditis is the most common cause of hypothyroidism in dogs.
True
What disease is associated with hyperthyroidsism in cats?
hypertrophic cardiomyopathy

can also see saddle thrombus
What is hypoparathyroidism?
occasionally recognized in dogs, particularly in smaller breeds

may be the result of lymphocytic parathyroiditis or the accidental removal or the parathyroid glands during thyroid surgery

Clinically there is increased neuromuscular excitability tremors and tetany

generalized tetany and convulsive seizures may occur

Affected animals have hypocalceimia and hyperphosphatemia

Because of increase renal tubular re absorption of phosphorus
T/F

Primary hyperparathyroidism can cause fibrous osteodystrophy.
True

parathyroid adenomas and carcinomas may secrete increased amounts of PTH leading to primary hyperparathyroid
What are characteristics of secondary hyperparathyroidism?
low calcium or high phosphorus diets

renal disease
What is Hummoral hypercalcemia of malignancy?
known as pseudohyperparathyroidism or paraneoplastic hypercalcemia (due to secondary bone metastases)

in these cases its is not considered a paraneoplastic syndrome
What is Primary Diabetes Mellitus?
type 1 (10%) lack of insulin production
type 2 (90%) lack of receptors response
What are examples of Secondary diabetes?
Secondary diabetes
-infectious
-gestational
With diabetes Mellitus, the presents of hyperglycemia cause what?
diabetic nephropathy due to destruction of the glomeruli causes glomerulosclerosis and renal failure

can see cararacts due to glucose is metabolized in the lens by a sorbitol pathways
-accumulation of large amounts of sugar alcohols in diabetics results in hypertonicity and opacity of the lens
T/F

Diabetes Mellitus is a relatively common endocrinopathy in male dogs and due to over feeding?
false

more common in female dogs as a caused by pancreatitis
T/F

Vascular lesions are not common in diabetic animals?
True

the are important in human diabetics
What can diabetes mellitus in cause secondarily in cats?
pancreatic islet amyloidosis
What is diabetic neuropathy?
seen in humans and primarily in cats

not ever cat will have peripheral neuropathy
the ones that do walk plantar instead of on their digits

the nerves of these animals will have axonal degeneration
axonal and myelin fragments present