Endocrine System Flashcards
what are some common features of the endocrine system?
- glandular epithelium (except posterior pituitary)
- richly vascularised
- secrete variety of hormones
- controlled by positive and negative feedback loops
what is the function of the pituitary gland?
coordinates the endocrine organs through feedback loops
what are the functional components of the pituitary gland and what is their structure?
posterior pituitary - downgrowth of hypothalamus
anterior pituitary - epithelial structure
what neural tissue does the posterior pituitary contain?
- axons
- glial cells
what does the posterior pituitary store and secrete?
- oxytocin
- ADH (vasopressin)
what stain would you use to see the nested architecture of the pituitary?
reticulin
what pituicytes are present in the anterior pituitary and what is their prevalence?
50% somatotrophs 25% lactotrophs 15-20% corticotrophs 10% gonadotrophs 1% thyrotrophs
what do somatotrophs secrete?
GH
what do lactotrophs secrete?
prolactin
what do corticotrophs secrete?
ACTH
what do gonadotrophs secrete?
- FSH
- LH
what do thyrotrophs secrete?
TSH
where are somatotrophs primarily found?
lateral wings of anterior pituitary
what is the shape of lactotrophs?
- polygonal
- cytoplasmic processes wrap around other cells
what is the shape of thyrotrophs?
- angular chromophobes
- elongated cytoplasmic processes
what is the shape of gonadotrophs?
scattered round/oval cells
what could you use to stain gonadotrophs?
- α subunit
- common to LH and FSH
- β unit of LH
- β unit of FSH
what is the shape of corticotrophs?
- round basophilic cells
- large cytoplasmic vacuoles
where are corticotrophs primarily found?
middle of gland
what colour do corticotrophs stain on H&E?
dark purple
what are sustentacular cells?
supporting cells that surround normal follicles
what would you use to stain sustentacular cells?
S100
what is a pituitary adenoma?
benign tumour of the pituitary
what can happen when the pituitary enlarges due to tumorous growth?
- sella turcica expands
- tumour grows out of sella turcica
- compresses optic chiasm
describe the histological structure of adenomas
- lose nestled architecture
- pituicytes arranged in rosettes
- central area of fibrillary material and capillary
what is the pineal gland?
conical structure just below posterior end of corpus callosum
what does the pineal gland secrete?
melatonin
what is the shape of the nuclei in the pineal gland?
central round
describe the histological structure of the pineal gland
- arranged in rosettes
- several pinealocytes arranged around central fabrillary area
what does the thyroid gland contain?
- follicular cells
- colloid
what does the thyroid gland produce?
- thyroxine
- calcitonin
what do follicular epithelial cells in the thyroid gland produce?
thyroxine
what do C-cells in the thyroid gland secrete?
calcitonin
what do the parathyroid glands produce?
PTH
how many parathyroid glands are there?
4
what are the cell types found in the parathyroid glands?
- chief cells
- oxyphils
- adipocytes
describe the histological structure of chief cells
- small polygonal cells
- scant cytoplasm
what cells in the parathyroid glands secrete PTH?
chief cells
describe the histological structure of oxyphil cells
- large polygonal cells
- abundant eosinophilic cytoplasm
which organ houses the islets of langerhans?
pancreas (mainly in tail)
describe the histological structure of the islets of langerhans
- balls of cells
- surrounded by thin fibrous capsule
what cells are found in the islets of langerhans and what is their prevalence?
70% beta-cells 20% alpha-cells 5-10% delta-cells 1-2% PP cells <1% epsilon
what do beta cells secrete and what is their action?
insulin
- lowers blood glucose conc.
what do alpha cells secrete and what is their function?
glucagon
- stimulates hepatic glycogenolysis → raise blood glucose conc.
what do delta cells secrete and what is their function?
somatostatin
- Inhibits gastric parietal cells → slows gastric acid secretion
what do PP cells secrete and what is their function?
pancreatic polypeptide
- Reduces gut mobility
- delays gastric emptying
what do epsilon cells secrete and what is their function?
ghrelin
- stimulates appetite
what are adrenal glands surrounded by?
adipose connective tissue
what are the principle layers of the adrenal glands?
- cortex
- medulla
what are the layers of the adrenal cortex?
- zona glomerulosa
- zona fasciculata
- zona reticularis
what does the zona glomerulosa of adrenal glands produce?
mineralocorticoids
- aldosterone
what does the zona fasciculata of adrenal glands produce?
glucocorticoids
- cortisol
what does the zona reticularis of adrenal glands produce?
androgenic steroids
describe the histological structure of the zona glomerulosa
- thin, incomplete
- small cells
- vacuolated cytoplasm
describe the histological structure of the zona fasciculata
- most prominent layer
- large polygonal cells
- almost clear cytoplasm
describe the histological structure of the zona reticularis
anastamosing columns of small polygonal cells
what are the shapes of the cells in the adrenal medulla?
large, polyhedral chromaffin cells
what does the adrenal medulla secrete?
- adrenaline
- noradrenaline
