Unit 6 - Endocrine Glands Flashcards
what are mechanisms of hormone actions?
- membrane-impermeable (hydrophilic)
- receptors located on cell surface (don’t enter cell)
- act via secondary messengers
- ex: peptides, PRO, glycoPRO, modified AA - membrane-permeable (hydophobic)
- intracellular receptors are DNA-binding PRO that affect transcription
- ex: steroid, TH
what are typical features of cells producing PRO hormones?
- abundant RER
- prominent Golgi
- hormones often stored in secretory granules
what are typical features of cells producing steroid normones?
- central nucleus
- lipid droplets in cytoplasm
- abundant SER for cholesterol synthesis
- spherical mitochondria with characteristic tubular/vesicular cristae
structure of anterior pituitary
derived from oral ectoderm
-consists of epithelial tissue = adenohypophysis
3 regions are pars tuberalis, pars distalis, and pars intermedia
structure of posterior pituitary
derived from neural ectoderm
-consists of neurons and glia = neurohypophysis
2 regions arei nfundibular stalk and pars nervosa
how are cells in anterior pituitary divided?
- chromophils - basophils and acidophils
2. chromophobes - stem/progenitor cells, cells that released granules, or lost granules during fixing
what are acidophils in anterior pituitary?
produce 2 types of PRO hormones
- somatotropic/GH
- mammotropic hormone/prolactin
what are basophils in anterior pituitary?
glycoPRO hormones: FSH, LH, TSH
small polypeptides: ACTH, beta-LPH (lipotropin)
what are the percentages of secretory cells in anterior lobe? the hormone secreted? its role?
somatotrope: 50% - GH - growth of long bones
lactotrope: 15-20% - PRL - stimulate milk secretion
gonadotrope: 10% - FSH and LH - regulate ovarian follicle development, spermatogenesis, estrogen, and androgen secretion
thyrotrope: 5% - TSH - regulate TH secretion
corticotrope: 15-20% - ACTH - stimulate adrenal cortex hormone secretion
- also lipotropin - promotes utilization of fat
first 2 are acidophilic, last 3 are basophilic
in what parts of the anterior pituitary are hormones produced?
pars distalis and pars tuberalis
-the pars intermedia is largely inactive in adults, and has colloid-filled follicles and (Rathke’s) cysts of unknown function
what kinds of cells does the neurohypophysis have?
axons and glial cells (pituicytes)
- has NO secretory cells
- cell bodies of neurons are in hypothalamus
- hormones are stored in dilated axons
- -eosinophilic dilations are called Herring bodies
structure and origin of adrenal glands?
have outer layer (cortex) and inner layer (medulla)
- cortex has epithelial origin and 3 concentric zones: zona glomerulosa outer - zona fasciculata - zona reticularis inner)
- medulla has neuronal origin
what kinds of cells are in the adrenal cortex?
typical features of steroid-producing cells; usually have foamy appearance = foam cells
- central nucleus
- acidophilic cytoplasm with lipid droplets
- abundant SER for cholesterol synthesis
- spherical mitochondria with characteristic tubular cristae contain enzymes involved in synthesis of steroid hormones from cholesterol
what kinds of cells are in the adrenal medulla?
cells have electron-dense secretory granules that react with chromium and silver salts (so called chromaffin or argentaffin)
-make catecholamines (epinephrine and norepinephrine)
what hormones are made by the adrenal cortex, and where?
zona glomerulosa: mineralcorticoids (mostly aldosterone to regulate salt balance)
-regulated by angiotensin II
zona fasciculata: glucocorticoids (mostly cortisol), some DHEA (regulate glucose metabolism)
-regulated by ACTH
zona reticularis: cortisol and weak androgen DHEA (glucose regulation and testosterone production)
-regulated by ACTH
what hormones are made by the adrenal medulla, and where?
all of medulla makes catecholamines (E/NE) for fight-or-flight response
-regulated by SNS
what happens to the adrenal cortex if the pituitary is removed, or there is a tumor?
no hypophysis: cortex gets smaller, medulla stays the same
tumor: cortex gets larger, medulla stays the same
Cushing’s syndrome
- effects
- ccauses
adrenal cortex hyperactivity
- excessive cortisol causes weight gain, central obesity, hyperglycemia, easy bruising
- ACTH-independent: 20%
- -adrenal adenoma: 10%
- -adrenal carcinoma: 5%
- -other causes: 5%
- ACTH-dependent: 80%
- -pituitary adenoma: 70%
- -ectopic ACTH secretion by a tumor: 10%
islets of Langerhans
compact masses of endocrine tissues embedded w/in exocrine tissue of pancreas
- polygonal/round cells arranged in cords
- typically PRO-secreting cells (abundant RER, golgi)
- lightly stained (lighter than exocrine tissue)
- cells have secretory granules
- make polypeptide hormones
what is the quantity of cell types in islets of Langerhans?
alpha: 20% - in periphery - make glucagon
beta: 70% - centrally located - make insulin
delta: 5-10% - make somatostatin to inhibit other islet hormones, inhibit GH, TSH, and HCl secretion
F or PP: very rare - make pancreatic polypeptide to stimulate gastric chief cells but inhibit bile and pancreatic enzyme secretion
where is the thyroid and structure?
anterior to trachea
- has follicles, spherical structures lined by simple epithelium and filled with colloid
- colloid has storage form of TH called thyroglobulin
what do thyroid follicular cells look like and do?
vary in shape from cuboidal to low columnar
- have features characteristic of PRO-secreting cells (abundant RER and golgi)
- activity regulated by TSH made in anterior pituitary
- T3/4 regulate basal metabolic rate, body growth/development, and heat production
what do parafollicular cells (C-cells) look like and do?
larger in size than follicular cells
- appear pale in H&E prep
- located in basal lamina of follicles or between follicles
- make calcitonin that inhibits bone resorption and promotes calcification of bone (opposite of PTH)
- regulated by blood Ca++ levels
there are parathyroid glands? what kind of cells do they have?
4 small oval glands on the back of the thyroid
- chief cells - make PTH
- oxyphil cells - no known function
what do parathyroid gland chief cells do?
abundant small polygonal cells that are pale staining, and slightly acidophilic cytoplasm
- make PTH (polypeptide) that increase blood Ca++ level by regulating osteoclast activity, kidney excretion of Ca++, vit D synthesis, and intestinal absorption of Ca++
- regulated by Ca++ level in blood
what do oxyphil cells of parathyroid gland do?
large cells that are highly acidophilic (thus oxyphilic)
- less abundant than chief cells
- unknown function, but may make some PTH
what are some hormones secreted by non-endocrine hormones?
heart - ANP
kidney - erythropoietin, reinin
stomach/SI - enteric hormones
adipose tissue - leptin, adiponectin, steroid hormones
what does ANP do?
in heart; regulates BP and electrolyte balance
what do adipose hormones do?
- leptin
- adiponectin
leptin: regulate appetite and metabolism
adiponectin: regulate FA and glucose metabolism, and modulates sensitivity to insulin
what does B-FLAT refer to?
basophilic cells of anterior pituitary secrete FSH, LH, ACTH, and TSH
what does GPA refer to?
GH and PRL are secreted by acidophilic cells of anterior pituitary
what does “salt, sugar, sex” refer to?
order or products of adrenal cortex:
- mineralcorticoids (aldosterone)
- glucocorticoids (cortisol)
- androgens
