Chapter 10: The Endocrine system Flashcards
Hormones vs. Neurotransmitters
hormones in blood; neurotransmitters in synapses epinephrine can be either
hormones
chemical messengers that are released in one tissue and transported by the bloodstream to reach target cells in other tissues
amino acid derivative hormones
small molecules structurally similar to amino acids: epinephrine, norepinephrine, thyroid hormones, melatonin
peptide hormones
chains of amino acids; largest class of hormones all hypothalamic, pituitary gland, heart, kidney, thymus, digestive, and pancreatic hormones, poterior pituitary (ADH, oxytocin)
lipid derivative hormones
two classes: steroids, aldosterone and eicosanoids (prostaglandins)
steroid hormones
insoluble in water, bind to specific transport proteins in the blood; lipid-soluble released by the reproductive organs and the adrenal glands
Eicosanoids
fatty acid-based compounds derived from 20-carbon fatty acid arachidonic acid; coordinate local cellular activities, affect enzymatic processes in extracellular fluids, including blood clotting; lipid-soluble include prostaglandins
g protein
an enzyme complex coupled to a membrane receptor
cyclic-AMP
most common second messenger; created by an enzyme called adenylate cyclase; activates kinase enzymes which attach high-energy phosphate group to another molecule
phosphorylation
The metabolic process of introducing a phosphate group into an organic molecule
adenylate cyclase
converts ATP to cAMP
kinase
enzyme that transfers phosphate ions from one molecule to another; activated by cAMP
phosphodiesterase (PDE)
breaks down cAMP
first messenger
A water soluble hormone that binds to its receptor at the outer surface of the plasma membrane because it cannot pass through cell membrane
Second messenger
acts as a signal molecule in the cytoplasmexamples include: cAMP, calcium ions, cyclic-GMP
methods of free hormone activation
- diffusing out of bloodstream/binding to target cells2. absorbed/broken down by liver or kidney3. broken down by enzymes in blood or interstitial fluids
regulatory hormones
Control release of hormones from anterior pituitary; may be releasing (RH) or inhibitory (IH)
posterior pituitary gland
releases ADH and oxytocin
anterior pituitary gland
releases TSH, ACTH, FSH, LH, PRL, GH, and MSH
hypophysis
pituitary gland
infundibulum
connects hypothalamus to pituitary gland
hypophyseal portal system
blood leaving capillary beds in hypothalamus travels to a capillary bed in anterior pituitary to allow for secretion of releasing hormones
tropic hormones
regulatory hormones
thyroid-stimulating hormone (TSH)
“thyrotropin”targets thyroid gland; released in response to thyrotropin-releasing hormone (TRH) from hypothalamusresults in secretion of thyroid hormones
adrenocorticotropic hormone (ACTH)
targets adrenal cortex; released in response to corticotropin-releasing hormone (CRH) from hypothalamusresults in glucocorticoid secretion
gonadotropins
FSH and LH released in response to gonadotropin-releasing hormone (GnRH) from hypothalamus regulates the activities of the male and female sex organs, or gonads
follicle-stimulating hormone (FSH)
targets follicle cells of ovaries, sustentacular cells of testes; released in response to GnRH; inhibited by inhibitinresults in estrogen secretion, egg follicle development, sperm maturation
luteinizing hormone (LH)
targets gonads; released in response to GnRHresults in ovulation, progesterone and esterone secretion, testosterone secretion
inhibin
inhibits secretion of FSH
prolactin (PRL)
targets mammary glands; released in response to prolactin-releasing hormone (PRH)results in production of milk
growth hormone (GH)
“human growth hormone (hGH)”targets all cells; released in response to GH-RHresults in growth, protein synthesis, lipid mobilization/catabolism; glucose-sparing effect
somatotropin
hGH
melanocyte-stimulating hormone (MSH)
targets melanocytes; virtually non-functional in humans except during fetal development, in very young children, in pregnancy, and in some diseasesresults in increased melanin synthesis
somatomedins
“insulin-like growth factors”peptide hormones that bind to receptor sites on a variety of cell membranes, increase the rates at which amino acids are incorporated into new proteins
glucose-sparing effect
causes tissues to use fatty acids instead of glucose as an energy sourceaccelerate rates of glucose synthesis/glycogen formation, releases fatty acids from adipose tissue into bloodstream; tissues break down fatty acids rather than glucose
antidiuretic hormone (ADH)
manufactured in hypothalamus, released by posterior pituitary gland, targets kidneysresults in reabsorption/conservation of water, elevation of blood volume/pressure, vasoconstrictionreleased in response to increased osmotic pressure or low blood volume
oxytocin
manufactured in hypothalamus, released by posterior pituitary gland, targets reproductive organsresults in smooth muscle uterine labor contractions, milk ejection, peaks during sexual activity
vasopressin
ADH; decreases water lost at kidneys and causes vasoconstriction
diabetes insipidus
posterior pituitary gland no longer releases adequate amounts of ADH or the kidney is resistant to its effect; water conservation is impaired; leads to polydipsia and polyuria
isthmus
connects the two lobes of the thyroid gland