Key Terminology & Definitions - Endocrine Flashcards
Euglyaemia
Normal glucose conc in blood
Primary hyperfunction
Disorders of growth e.g. neoplasia, hyperplasia, PPID
Secondary hyperfunction
Secretion of excessive trophic hormone in one organ leads to long-term stimulation of a target organ (produces more hormone)
Primary hypofunction
Direct injury - less of endocrine organ, can’t function same amount e.g. immune-mediated lymphoplasmocytic hypophysis (in dogs)
Secondary hypofunction
Destruction of one organ interferes with secretion of trophic hormone e.g. failure of foetal endocrine func, veratrum californicum plant affects pregnant ewes
Apoplexy
Bleeding into an organ or loss of blood flow to an organ
Hypophysitis
Inflammation of pituitary gland
Diabetes insipidus
Savoury urine - extra water in urine due to ADH dysfunction (produced by neurohypophysis)
Diabetes mellitus
Sweet urine due to glucosuria
Central diabetes insipidus (CDI)
Inadequate synthesis and release of ADH, will respond to to exogenous administration of ADH, compresses/destroys parts of neurohypophysis that produce ADH (pars nervosa, infundibular stalk. supraoptic nucleus)
Nephrogenic diabetes insipidus (NDI)
Failure of renal tubular epithelial cells to respond to ADH, won’t respond to exogenous ADH
Pituitary pars intermedia dysfunction (PPID)
(Equine) Due to a pars intermedia (melanotroph) adenoma - micro/macro, diffuse adenomatous hyperplasia of pituitary gland, melanotrophs produce excessive proopiomelanocortin (POMC), cleaved into alpha-MSH, beta-endorphin and CLIP -> excess hormones,
Hypertrichosis/hirsutism
Excessive hair growth
Adenohypophysealaplasia
No formation of pituitary gland
Cyclopia
Ring-eyed, no nose
Panhypopituitarism
Dec production and secretion of all hormones of pituitary gland -> pituitary dwarfism
Cranipharyngeal duct cysts
Pituitary cysts - may develop from remnants of distal craniopharyngeal duct, normally disappears by birth, lined by respiratory epithelium, filled with mucin, small - not clinically relevant
Rathke’s cleft cysts
Result from a failure of Rathke’s pouch ectoderm to differentiate into the adenohypophysis, leads to progressively enlarging cyst lined by respiratory epithelium + filled with mucin, enlarging cyst crushes adenohypophysis -> failure of adenohypophysis development - panhypopituitarism and pituitary dwarfism
Pituitary dwarfism
Autosomal recessive disease most commonly in German Shepherd puppies, subnormal growth
Hypersomatotropism
= Feline acromegaly, result of an adenoma/adenomatous hyperplasia
Thyroid follicular cells
Produce thyroglobulin, single layer of columnar/cuboidal cells around colloid
Thyroid C-cells
= Parafollicular cells/medullary cells, found beside follicles, produce calcitonin, not controlled by TSH, respond directly to plasma conc of Ca^2+ (long term hypercalcemia results in hyperplasia of C cells)
Calcitonin
Polypeptide hormone, stored in granules, opposes effects of parathyroid hormone, dec Ca^2+, secreted by C cells
Ectopic thyroid tissue
Can be source of thyroid hormone after thyroidectomy.; can be site of thyroid carcinoma, occurs anywhere from bases of tongue to diaphragm, functional nodules common in base of heart of dogs
Thyroglossal duct cysts
Derived from remnants of thyroglossal duct, can form cysts of sinus tracts on the ventral midline of the neck
Atherosclerosis
Too much cholesterol and fat deposits in blood vessels (become white and thicker), caused by hypercholesterolaemia
Myxoedema
Swelling of the skin and underlying tissues giving a waxy consistency - hypothyroidism, ‘tragic’ facial expression
Goitre
Non-neoplastic enlargement of the thyroid caused by follicular hyperplasia
Diffuse goitre
Typically compensatory, TSH-induced response to hypothyroidism
Multinodular goitre
Hyperplastic follicular cells acting autonomously (independent of TSH) to cause hyperthyroidism e.g. in old cats
Groups of delinquent thyroid follicular epithelium ignore the hypothalamus & pituitary gland
Rest of thyroid gland undergoes atrophy (negative feedback resulting in low TSH)
Goitrogens
Substances that cause hyperplastic goitre
Colloid goitre
Involutionary stage of goitre, when blood T4 and T3 return to normal
Pheochromocytoma
Derived from chromaffin cells.
Parathyroid hormone
Mobilises calcium from bone (bone resorption)
Vitamin D
Inc calcium uptake from gut (major target)
Calcitriol
Active form of vitamin D produced in proximal tubular cells of kidney, retention of calcium in bone, acts on bone directly and indirectly by stimulating osteoclastic bone resorption + inhibiting PTH secretion, formed
Calcidiol
Inactive form of vitamin D
Calcitonin
Stored in granules, opposes effects of PTH, secreted by C cells in response to hypercalcaemia, acts on bones + kidneys -> hypocalcemia + hypophosphataemia
Parathyroid hormone-related peptide (PTHrP)
Structurally similar to PTH, produces humoral hypercalcaemia of malignancy (HHM) by secretion of PTHrP by cancer cells
Parturient hypocalcaemia
Severe hypocalcaemia due to rapid change in physiological calcium demands
Dysecdysis
Abnormal shedding
Pseudohyperparathyroidism
= Humoral hypercalcaemia of malignancy (HHM) - secretion of parathyroid hormone-related protein (PTHrP), causes hypercalcaemia + soft tissue mineralisation
Dyshormonic goitre
Rare cause of congenital hypothyroidism occurring due to a lack of enzymes necessary for the synthesis of thyroid hormones, morphologically characterised by architectural and cellular pleomorphism that may mimic thyroid malignancy and cause difficulties in differential diagnosis.
Metastatic mineralisation
Hypercalcaemia, too much in blood
Dystrophic mineralisation
Cells breaking down, contain a lot of Ca^2+, creates foci of necrosis
Lardaceous
Having a fatty or waxy texture resembling lard, or affected by deposits of this kind
Calcinosis cutis
Accumulation of calcium salt crystals in skin - calcification of degenerate collagen, localised (dystrophic calcification)
Phaeochromocytoma
Neoplasia of adrenal medulla, rare, mostly seen in dogs and cattle, may be benign or malignant, may secret catecholamines (adrenaline and noradrenaline)
Pancreatic islets
Masses of endocrine tissue (secrete hormones) embedded within the exocrine tissue of the pancreas
Glucagon
Produced by alpha-cells near periphery of islet, polypeptide - acts on several tissues to make energy stored in glycogen and fat available through glycogenolysis and lipolysis; increases blood glucose content + gluconeogenesis, due to hypoglycaemic effects of insulin
Insulin
Produced by beta-cells centrally + more numerous in islet, dimer of and chains w/ S-S bridges, acts on several tissues to cause entry of glucose into cells and promotes decrease of blood glucose content in response to hyperglycaemia
Somatostatin
Produce by delta-cells, less abundant in islet, polypeptide, inhibits release of other islet cell hormones (glucagon, insulin) through local paracrine action; inhibits release of GH and TSH in anterior pituitary and HCl secretion by gastric parietal cells
Pancreatic polypeptide
Produced by F or PP cells of islet, rare, polypeptide, stimulates activity of gastric chief cells; inhibits polypeptide
bile secretion, - pancreatic enzyme and bicarbonate secretion, and intestinal motility, antagonises effects of cholecystekinin, inhibits exocrine pancreatic secretion + gall bladder contraction, delaying gastric emptying
Grehlin
Produced by epsilon-cells - appetite inc, insulin secretion suppression
Nesidioblastosis
Non-neoplastic proliferation (hyperplasia) of islet and ductular tissue and is typically an incidental finding
Paraganglioma
AKA chemodectomas, endocrine tumour mostly in dogs (brachycephalic), derived from chemoreceptor organs, a collection of neuroepithelial cells normally associated with the parasympathetic nervous system - breathing + circulation, changes in blood e.g. CO2, pH, O2 tension, tumour develop principally in the carotid and aortic bodies of animals at base of heart
Malassezia dermatitis
Part of normal flora of skin of dogs and cats -> overgrowth
Atrophy
Decrease in the mass of a tissue due to decreased size + number of cells (after it has reached its normal size)
Dermal atrophy
Thinning of dermal collagen fibrils -> decreased dermal thickness
Hyperhidrosis
Episodically moist/greasy skin which can matt coat (inc sweating), prolonged anagen of hair follicles = environment for bacteria to grow
