Endocrine Flashcards
what type of cells make up endocrine glands?
epithelial cells
what are the three classes of hormones and how are these classified?
classified based on their chemical structure into peptides, steroids and amino acids
name examples of the three hormone classifications
amino acids e.g. thyroid hormones
steroids e.g. gonadal and adrenocortical steroids,
peptides e,g, insulin, ACTH, GH.
what is the consequence of lacking ducts in endo glands?
the secretions by parenchymal cells move into interstitial space where they reach their target cells via extracellular CT/ vascular system/
what types of hormones do cell surface and intracellular receptors interact with?
cell surface: peptide and catecholamine
intracellular: steroids and thyroid hormones
what are the two systems by which hypothalamus coordinates endocrine functions, and what does each involve?
hypothalamo-hypophyseal tract which involves paraventricular and supraoptic nuclei linked to posterior lobe of pituitary.
hypothalamo-hypophyseal portal system which carries neuroendocrine secretions of hypothalamus directly to the anterior lobe.
different names of anterior pituitary and posterior pituitary?
anterior: adenohypophysis, pars distalis
posterior: neurohypophysis and pars nervosa.
what is the origin of superior hypophyseal arteries and what do they supply?
they arise from internal carotid and PCA of Willis,
they supply infundibulum, pars tuberalis, median eminance.
origin of inferior hypophyseal arteries and their supply?
arise only from ICA, supply pars nervosa.
T/F: most of the anterior lobe doesn’t have a direct arterial supply.
true
where do primary and secondary capillary plexuses come from and
primary:arteries that supply infundibulum, median eminance and pars tuberalis
Secondary: hypophyseal portal veins
what is the path of hypothalamo-hypophyseal portal system?
secretions go from infun, M.eminance, and P.Tuberalis via primary capillary plexus which drains into hypophyseal portal veins which themselves give rise to secondary C.P which releases those secretions into pars distalis.
what are the divisions of adenohypo?
pars distalis (anterior lobe), pars intermedia and pars tuberalis.
what cells give rise to pars intermedia?
vestigial left over cells from Rathkespouch
what cells does pars distalis consist of?
cords of glandular epi cells within a rich network of large fenestrated cap.
what are three classes of cells in adeno?
basophils, acidophils and chromophobes.
what is the function of folliculostellate cells?
start shaped, connect p.Tuberalis to p.distalis via gap junctions to coordinate hormone release
what are the different cell types in acidophils and basiphils?
acido: somatotrophs and mammotrophs
baso: cortico, gonado and thyro
what does neurohypophysis produce?
oxytocin and antidiuretic hormone/ADH
what nuclei produce oxytocin and ADH?
supraoptic and paraventricular
what is the pathway of hormone secreted to go to neurphypophysis
oxy and ADH are secrete from paraventricular and supraoptic respectively which move down the nonmyelinated axons of hypo-hypo tract and get stored in accumulation if neurosecretory granules called herring bodies.
function of pars intermedia?
release melanocyte-stimulating hormone and endorphins
what cells constitute pars intermedia?
chromophobes and basophils which surround small spaces filled with eosinophilic colloid.
what do parafollicular cells secrete and the secretions’ role?
calcitonin, in concert with parathyroid hormone regulates blood calcium levels.
what is stored as colloid in thyroid gland?
inactive form of thyroid hormone called thyroglobulin-eosinophilic staining
what is the functional unit of a thyroid gland?
thyroid follicle
what type of epi is a follicular cell
simple cuboidal
what is the appearance of the follicular cells in active thyroid?
follicles are small and the cells appear taller , but in inactive thyroid, follicles are large and distended and the cells are flat.
what’s another name of parafollicular cells?
clear cells as they lack staining
describe the path of thyroglobulin production
- made in rER, packaged in golgi and then stored in colloid.
- Iodide is taken from the blood goes to colloid
- iodination occurs
- thyroglobulin becomes T3 and T4.
- resorption of T4 T3 occurs via lysosomal (5L) and receptor mediated (5TE)/ pathways
- t3 and t4 released into blood
T/F parafollicular cells share basal lamina and their lumen with follicular cells
false, they share BL but not the lumen. they have no exposure to FC lumen
what are the key features which help to identify PFC in EM level?
prominent golgi apparatus, many vesicles ranging from 60 to 550 nm.
what’s the function of calcitonin?
prevents ca release by altering osteoclast function thus inhibits bone resorption
what is the embryonic origin of parathyroid glands?
3rd and 4th pharyngeal pouches, distinct from thyroid.
what are the functional components of parathyroids?
principal (chief) cells and oxyphil cells.
what do principal cells secrete?
parathyroid hormone
what’s the function of PTH?
regulates calcium and phosphate levels via e ways;
- bone resorption 2. kidney calcium reabsorption via distal tubule while inhibiting phosphate reabsorption in proximal tubule.
- increases formation of active vitamin D in kidney promoting tubular reab of calcium
what is within chief and oxyphil cells?
chief: abundant granules, glycogen and lipid droplets
oxyphil: larger cyto, more acidophilic, and NO granules, vesicles or rER.
what’s the function of PTH?
regulates calcium and phosphate levels via e ways;
- bone resorption 2. kidney calcium reabsorption via distal tubule while inhibiting phosphate reabsorption in proximal tubule.
- increases formation of active vitamin D in kidney promoting tubular reab of calcium
what is within chief and oxyphil cells?
chielf: abundant granules, glycogen and lipid droplets
oxyphil: larger cyto, more acidophilic, and NO granules, vesicles or rER.
what are the types of tissues inb adrenal gland and what do each secrete?
adrenal cortex secretes steroid hormones: mineralocorticoids, glucocorticoids and sex hormones.
adrenal medulla secretes catecholamine hormones: adrenaline and noradrenaline.
what is the blood supply of suprarenal gland?
superior middle and inferior suprarenal arteries which upon entering the capsule become capsular capillaries, cortical capillaries. also have medullary arterioles.
drainage of the suprarenal gland?
medullary capillaries give rise to venules which drain into small collecting veins then join the central vein which itself drains into left renal vein.
what are the divisions of adrenal cortex?
3 zones: zona glomerulosa, zona fasciculata, zona reticularis.
describe the types of cells and secretions in each zone of adrenal cortex.
Z.G: 15%, clusters of round cells, secretes mineralocorticoids e.g. for electrolyte and fluid homeostasis.
Z.F: 80%, parallel cords, perpendicular to capsule, secrete glucocorticoids for carbs, lipids and protein metabolism.
Z.R: 5%, irregular cords, secrete gonadocorticoids which supplement gonadal hormone secretion.
what zone of adrenal cortex produces aldosterone, its function and what controles its secretion?
cells of zona glomerulosa. it controls blood pressure by regulating sodium and potassium levels. Renin angiotensin aldosterone system/RAAS controls this.
what is the feature of zona glomerulosa cells in terms of shape and contents?
pyramidal shaped, small, strong stainign nuclei, sparce lipids but abundant sER.
what are the key features of cells of zona fasciculata in terms of shape and contents ?
polyhedral shaped, long cord arrangement, light stain nuclei, may be binucleated, full of lipid, pale cyto, prominent ER both s and r.
what zone/s of adrenal cortex secretes glucocorticoids like cortisol and function?
zona fasciculata, regulation of glucose and FA metabolism. limited amount by zona reticularis.
features of zona reticularis in terms of cell shape, types of capillaries, cell content?
anastomosing cords of small cells, less cyto, dense nuclei so dark staining, closely packed, capillaries are fenestrated, contain abundant sER, mito but little rER.
what does zona reticularis secrete?
gonadocorticoids like adrenaladrogens such as DHEA but also secrete limited glucocorticoids
what type of cells does adrenal medulla consist of and what do they secrete?
chromaffin cells,interspersed with sinusoidal capillaries and extensive collecting veins, cells have larger glandular nuclei and extensive basophilic cyto, symp NS nerves press directly here to produce catecholamines like adrenaline.
how does adrenaline granules appear and differ from noradrenaline?
adrenaline appears light and small, nor is large and dark
what is the name of the main pancreatic duct?
duct of wirsung
how do islets of langerhan develop?
they migrate from the duct system and aggregate around the capillaries forming islets.
what are the cell types found in pancreatic islets of langerhan and secretions?
principle: alpha: glucagon, beta:insulin and delta: somatostatin
minor: pancreatic polypeptide cells
Glucagon is stored in …..nm vesicles
250
difference between beta cell and alpha cell vesicles?
alpha glucagon vesicles are more uniform in size and more densely packed in cyto unlike beta cells.
how do alpha, beta and delta cells vary in terms of location of cells and proportion of them?
a cells are scattered across islets and comprise 20% of the islet
beta cells are centrally located and comprise 70%
delta cells are less abundant 5-10%
what size are the vesicles of a, b and d cells?
a=250
b=300
d=350 nm
what stimulates insulin secretion?
increase in BGL above 70mg/100 mL, below this glucagon is released.
how does insulin get synthesised and processed?
- preproinsulin is made in rER then proinsulin is made which is then transferred to Golgi which is packaged in vesicles.
what type of capillary surrounds islets of Langerhan?
fenestrated
role of somatostatin?
inhibits glucagon and insulin, -regulates a and b cell function.
