Endocrinology Flashcards
(686 cards)
what are endocrine glands?
ductless glands of the endocrine system that secrete their products directly into the blood
what are exocrine glands?
- glands that secrete substances onto an epithelial surface by way of a duct
- e.g. sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, mucous, pancreas
what are types of hormone action?
- endocrine (cell targets distant cell through bloodstream)
- paracrine (cell targets adjacent/nearby cell)
- autocrine (cell targets itself)
- holocrine (rupture of plasma membrane, destroying cell and secretion of product into lumen)
- merocrine (secretions excreted via exocytosis into duct)
- apocrine (apical portion of cell pinches off and becomes extracellular vesicle)
what are characteristics of water-soluble hormones?
- unbound transport
- bind to surface receptor
- short half-life
- fast clearance
- e.g. peptides, monoamines
what are characteristics of fat-soluble hormones?
- protein bound
- diffuse into cell
- long half-life
- slow clearance
- e.g. thyroid hormone, steroids
what are are characteristics of peptide hormones? what is the structure, storage, release, clearance like?
- vary in length
- linear or ring structures
- two chains and may bind to carbohydrates
- stored in secretory granules
- hydrophilic
- released in pulses or bursts
- cleared by tissue or circulating enzymes
what catalyses the formation of L-tyrosine from L-phenylalanine?
phenylalanine hydroxylase
- 6-BH4 affects this
what catalyses the formation of L-dopa from L-tyrosine?
tyrosine hydroxylase
- 6-BH4 affects this
what catalyses the formation of dopamine from L-dopa?
L-aromatic amino acid decarboxylase
- pyridoxal phosphate affects this
what catalyses the formation of norepinephrine from dopamine?
dopamine-beta-hydroxylase
- ascorbate affects this
what catalyses the formation of epinephrine from norepinephrine?
phenylethanolamine-N-methyltransferase
- S-adenosyl methionine affects this
- site of cortisol potentiation
what can be produced from norepinephrine? what catalyses this?
norepinephrine -> normetanephrines
- catalysed by catechol-O-methyltransferase
what can be produced from epinephrine? what catalyses this?
epinephrine -> metanephrines
- catalysed by catechol-O-methyltransferase
what can be produced from normetanephrines and metanephrines? what catalyses this?
vanillylmandelic acid
- catalysed by monoamine oxidase A
what is the pathway of cortisol synthesis?
cholesterol -> pregnenolone -> progesterone -> 17-hydroprogesterone -> 11-deoxycortisol -> cortisol
what is the pathway of estriol production?
cholesterol -> pregnenolone -> 17-hydroxypregnenolone -> DHEA -> androstenedione -> testosterone/estrone -> estradiol/16alpha-hydroxysterone -> estriol
what enzyme catalyses the formation of 17-hydroxypregnenolone from pregnenolone?
17 alpha-hydroxylase
what enzyme catalyses the formation of 17-hydroxyprogesterone from progesterone?
17alpha-hydroxylase
what enzyme catalyses the formation of 11-deoxycortisol from 17-hydroxyprogesterone?
21-hydroxylase
what enzyme catalyses the formation of cortisol from 11-deoxycortisol?
11beta-hydroxylase
what enzyme catalyses the formation of estradiol from testosterone?
aromatase
what enzyme catalyses the formation of estrone from androstenedione?
aromatase
what enzyme catalyses the formation of testosterone from androstenedione?
17beta-hydroxysteroid dehydrogenase
what enzyme catalyses the formation of dihydrotestosterone from testosterone?
5alpha-reductase