Lecture 36: Endocrine Flashcards
difference in formation of endocrine vs exocrine glands
both invaginate into the connective tissue but exocrine remains in a duct that secretes into the lumen, endocrine is separated and duct cells dissapear
two types of endocrine cells
cord/cluster and follicle (these are both surrounded by capillaries)
hormones
chemical substances synthesized by endocrine cells and secreted
where do hormones get secreted
into bloodstream(distant target cells), into tissue space (adjacent or nearby target cells), onto own cell surface (own target cells)
three signaling mechanisms
- endocrine
- paracrine
- autocrine
endocrine signaling
secreted into the blood
paracrine signaling
secreted into extracellular space (eg somatostatin inhibits insulin secretion in islets of langerhan)
autocrine secretion
secreted on own cell surface (eg insulin, TGF beta)
what are the three types of hormones chemically speaking
- peptides and glycoproteins (pit hormones, parathyroid, islets of langerhan and GI tract)
- steroids (hormones of adrenal cortex, ovary and testis)
- amino acids (tyrosine) eg hormones of thyroid and adrenal medulla
on an EM what is noticeable about peptide/glycoprotein hormones
contain granules which store the hormones
steroid hormone producing cells on EM
hormones not stored in cells
Endocrine glands whose sole functions are hormone production
PPPAT Pituitary Pineal Thyroid Parathyroid Adrenal
endocrine tissues found in association with organs which have other functions
pancrease, ovary, testis, kidney, liver
diffuse endocrine system
single hormone producing cells diffusely scatted in the digestive and respiratory systems
where is the pituitary located
beneath the floor of the third ventricle, connected to the hypothalamus
other word for pituitary
hypophysis
where does the pituitary lie
in the hypophyseal fossa, a bony depression of the sella turcia of the sphenoid bone
other word for anterior pituitary
adenohypophysis / pars distalis
parts of anterior pituitary
pars tuberalis
pars intermedia
parts of posterior pituitary
infundibulum (pituitary stalk) and median eminence (hypothalamus)
other word for posterior pituitary
neurohypophysis / pars nervosa
where do the neurohypophysis (posterior pit) and adenohypohysis (anterior pit) originate from
neuro = nervous tissue of the hypothalamus
adeno = ectoderm of the roof of the mouth
DIFFERENT EMBRYO SOURCES
how many hormones and cell types in the pituitary
6 hormones
1) GH
2) Prolactin
3) Corticotropin (ACTH)
4) FSH
5) LH
6) Thyrotropin (TSH)
5 cell types because FSH and LH are from the same cell type
where are anterior pituitary hormones stored
in the granules
