Endocrine 1 Flashcards
endocrine glands are
collections of specialized cells that synthesize, store, and release hormones to maintain homeostasis
hormones produced by endocrine cells enter the bloodstream and act on ________ __________ ________
distant target cells
endocrine diseases are often associated with a wide variety of
biochemical changes, multi systemic clilnical signs, and lesions outside of the endocrine system
hypothalamic neurosecretory cells release which hormones
releasing and release-inhibiting hormones [ex - thyroid stimulating hormone (TSH), Adrenocorticotropic hormone (ACTH), Gonadotropic Releasing Hormone (GnRH)]
the anterior pituitary gland releases which hormones
trophic hormones - ACTH, TSH, LH, FSH
endocrine glands are subject to all forms of injury but are particularly prone to
disturbances in growth - atrophy & proliferation
proliferation of an endocrine gland can be caused by
hyperplasia, adenoma, and carcinomas
although there are several mechanisms, the majority of disease processes result in either ____________ or __________ hormone production
insufficient (hypo function) or excessive (hyper function) hormone production
7 mechanisms of endocrine disease
- hypofunction of an endocrine gland
- hyperfunction of an endocrine gland
- Hypersecretion of hormones or hormone-like factors by a non-endocrine tumour
- dysfunction caused by failure of target cell response
- hyperactivity caused by diseases in other organs
- dysfunction due to abnormal hormone degradation
- Iatrogenic hormone excess
how many types of hypo function are there
2 - primary and secondary
primary hypofunction
lesion is in gland in question - biochemical defect in synthetic pathway , failed to develop, destruction (immune-mediated or neoplasia)
secondary hypo function
destructive lesion in one organ leads to hypo function of another, failure of trophic hormone production, usually pituitary lesion (non-functional tumour)
hyper function has how many types
2 - primary or secondary
primary hyperfunction
-hyperplastic nodule or neoplasm of endocrine gland
-autonomously secrete a hormone in excess of body’s ability to use/degrade
secondary hyperfunction
- a lesion in one organ results in stimulation and hyper secretion of hormone in target lesion
- excess production of trophic hormone
-pituitary neoplasm (functional)
example of hyper secretion of hormones or hormone-like factors by a non-endocrine tumour
humoral hypercalcemia of malignancy - neoplasm releases PTH neurohormone
the pituitary gland has 2 components
adenohypophysis (anterior pituitary), neurohypophysis (posterior pituitary)
the adenohypophysis has 2 parts
pars distils, pars intermedia
pars distalis has a variety of cells that produce
trophic factors - each cell type is under the control of a releasing hormone from the hypothalamus
what hormones are produces in the pars distails
GH, PRL, TSH, FSH, LH, ACTH
which hormones are produced in the pars intermedia
ACTH in dogs, MSH
what are the predominant cells in pars intermedia
melanotrophs
which hormones are produced in the neurohypophysis
oxytocin, ADH
- neurons originate in hypothalamus
disorders of the adenohypophysis
hypopituitarism & hyperpituitarism
disorders of neurohypophysis
diabetes insipidus
things that can cause hypopituitarism
aplasia and prolonged gestation, pituitary cysts, nonfunctional tumours that destroy the pituitary
things that can cause hyperpituitarism
functional (ACTH) secreting tumours
examples of functional secreting tumours in hyperpituitarism
-corticotrophin (ACTH- secreting) adenomas
- melanotroph adenomas of the pars intermedialis
-somatotroph adenomas
hypopituitarism - aplasia and prolonged gestation - mechanism
parturition requires intact fetal hypothalamic-pituitary-adrenocortical axis - if not intact, fetus can’t trigger parturition
what happens when the dam eats veratrum californicum (skunk cabbage) on day 14 of gestation
a neural tube defect in the fetus that leads to numerous craniofacial defects including cyclopia (1 eye + 1 orbit) and aplasia or malformation of the adenohypophysis
veratrum californicum ingestion on day 14 causes (hypo/hyper)pituitarism
hypopituitarism
is cyclopia more likely to happen in ruminants or dogs and cats or horses
primarily ruminants
pituitary cyst mechanism of hypopituitarism
failure of oropharyngeal ectoderm of Rathke’s pouch to differentiate into the pars distils
- autosomal recessive in GSD
pituitary cyst hypopituitarism condition called
Juvenile panhypopituitarism (pituitary dwarfism)
pituitary cyst hypopituitarism presentation
failure to grow, retention of puppy coat
- hypoadrenocortism and hypothyroidism
hypopituitarism - nonfunctional pituitary neoplasms - most often occur in
dogs & cats
nonfunctional pituitary neoplasms - adenomas or carcinomas?
adenomas > carcinomas
clinical signs of nonfunctional pituitary neoplasms due to
-hypofunction of pituitary and diminished target organ function (hypothyroidism, hypoadrenocorticism, gonadal atrophy in intact animals)
- CNS compression [weakness, ataxia, blindness, diabetes insipidus (no ADH produced)]
hyperpituitarism - Corticotroph or adrenocorticotropic hormone (ACTH)-secreting adenoma is seen most in what species
dogs, but increasingly in cats
Corticotroph or adrenocorticotropic hormone (ACTH)-secreting adenoma - what cells are affected
Corticotrophs of pars distalis or intermedia (dogs)
Corticotroph or adrenocorticotropic hormone (ACTH)- secreting adenoma - what happens to the adrenal gland
Bilateral adrenocortical hypertrophy/hyperplasia (zona fasciculata & zona reticularis)
ACTH secreting adenoma - clinical syndrome of what
Hyperadrenocorticism (cushing’s disease) - 85-90% of HAC due to pituitary tumour
PPID
Pituitary Pars Intermedia Dysfunction
Facts about PPID
-Most common endocrine dz of horses
- horses at around 15 yrs
PPID - loss of what inhibition
Loss of dopaminergic inhibition of the pars intermedia
PPID - what kind of lesion / adenoma
Melanotroph hyperplasia/adenoma
PPID leads to excessive production of
POMC and its derivatives including ACTH
Clinical syndrome of PPID is mainly the result of
Hypothalamic/neuropophyseal dysfunction
- hypertrichosis
- recurrent infections
- PU/PD
- weight loss
- abnormal sweating
- laminitis - concurrent equine metabolic syndrome
- neurological signs
Somatotroph adenoma leads to
Acromegaly - hypersecretion of growth hormone - can end up leading to insulin-resistant diabetes mellitus
Problems of the neurohypophysis
Diabetes insipidus (hypophyseal/central, nephrogenic forms)
Diabetes insipidus causes an inability to concentrate
Urine - produce large volume of dilute urine and PU/PD
Hypophyseal / central form of diabetes insipidus
Inadequate production of ADH
-compression/destruction of the neurohypophysis or hypothalamus
Nephrogenic form of diabetes insipidus
Inability of target cells in kidney to respond to normal to increased levels of ADH
Correct cortical:medullary ratio of adrenal glands
1:2:1 cortical:medullary:cortical ration
Cortex adrenal glands 3 layers (listed from outside in)
Zona glomerulosa, zona fasciculata, zona reticular is
Medulla of adrenal gland produces
Catecholamines (nor + epinephrine)
Zona glomerulosa of adrenal glands produce
Mineralocorticoids (aldosterone) - REGULATES SALT!!!
Zona fasciculata secretes
Glucocorticoids - regulates SUGAR
Zona reticularis of adrenal glands regulates
Sex hormones
Disorders of the adrenal cortex
Hypoadrenocorticism (addison’s dz)
Hyperadrenocorticism (cushing’s)
Adrenal neoplasia of ferrets
Disorders of the adrenal medulla
Neoplasms (pheochromocytoma)
Hypoadrenocorticism is most common in
Dogs
Addison’s affects _____________ layers of cortex
ALL! All are decreased
Signs of addison’s dz
Mineralocorticoid deficiency (severe hyperkalemia, severe hyponatremia)
Glucocorticoid deficiency (GI signs, hypoglycemia, low cortisol and no response to ACTH stimulation test)
-vomiting, diarrhea, weakness, lethargy, cardiovascular collapse (electrolyte imbalance)
Idiopathic adrenocortical atrophy - characterized by
Bilateral adrenal cortical atrophy in young adult dogs
Idiopathic adrenocortical atrophy - cause
Unknown, but immune mediated is likely
Gross lesions addison’s dz
Often nothing other than really small adrenal glands
Cushing’s dz - syndrome of cortisol excess - effects on protein, glucose, and lipids in body
Glyconeogenetic, lipolytic, protein catabolic, anti-inflammatory
What is one of most common endocrinopathies in dogs
Cushing’s dz - rare in cats, rare in other species
Mechanisms of cushing’s disease
1) functional corticotroph (ACTH) pituitary adenoma (85-90%)
2) functional adrenal gland neoplasm (10-15%)
3) iatrogenic
What is most common pathogenic mechanism of cushing’s
Functional corticotroph pituitary adenoma
Cushing’s dz clinical signs (long one sorry)
-PU/PD
-increased appetite
-muscular atrophy
-pendulous abdomen
-lordosis
-trembling
-straight-legged braced position
-cutaneous lesions (alopecia, thin skin, calcification [calcinosus cutis])
-hepatomegaly
-secondary infections
-impaired wound healing
Cause of cushing’s most likely to cause hepatomegaly
Steroid hepatopathy
Adrenal cortical neoplasia types
Adenoma & carcinoma
Adrenal cortical neoplasia - adenoma
Most common in older dogs - often incidental, but can be functional
- usually yellow bc of steroid hormones
Adrenal cortical carcinoma
Less common than adenomas
-older cattle and dogs
-can be functional;
-metastasis to liver, kidney, lymph nodes, and lungs
Adrenal disease in ferrets - happens most in
Females > males - extremely common !!!!
Adrenal disease in ferrets linked to
Early gonadectomy
Adrenal dz in ferrets - spectrum of proliferative lesions that cause same clinical syndrome
Hyperplasia (45%) = carcinoma (45%) > adenomas (10%)
- can be unilateral or bilateral
Adrenal dz in ferrets - affects which layer of the cortex
Zona reticularis (sex hormones)
- increased estradiol but normal cortisol
Clinical signs of ferret adrenal disease
Bilaterally symmetrical alopecia (both sexes)
Enlarged vulva
Prostatic enlargement and urethral obstruction
Pancytopenia (both sexes)
Pheochromocytoma is the most common tumour of
Adrenal medulla
Who normally gets pheochromocytoma
Dogs & bulls
are pheochromocytoma benign or malignant
both forms exist
are pheochromocytomas functional?
some are functional - excessive catecholamine release
- cause hypertension
pheochromocytoma appearance
arise in the medulla - dark red and compress the adjacent cortex
