IB 140 - Topic 1
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82 terms
Terms | Definitions |
|---|---|
 Endocrinology | Study of endocrine glands and the physiological effects of their hormone secretion. |
| What is hormone regulation influenced by? | Pituitary Gland in the brain and the CNS |
| What is the endocrine system | Ednocrine cells secrete homrones which are released into adjacent tissue space where they enter the bloodstream. |
| What are hormones | CHemical substances formed in one organ or part of the body and carried int he blood to another organ or body part; chemical messengers; they signal certain tissues to grow or change their cellular activity |
| Steroid Hormones | derived from cholesterol; androgens; estrogens; progestogens |
| Hormone Receptors | target tissues are responsive to a given hormone and have specific receptors on their cell membrane or on their nucleus to respond to a particular hormone molecule |
| Paracrines | Chemical messengers that are produced by endocrine cells and diffuse to act locally on adjacent cells with appropriate receptors; not carried in the blood stream. |
| ligand | a molecule that bind to a receptor |
| protein and peptide hormones | GnRH, FSH, LH, and PRL |
| Extracellular domain | hormonal signal is received when ligand attaches to ligand-binding site in extracellular membrane that sticks out beyond the cell. |
| Transmembrane domain | anchors receptor within within plasma membrane |
| Intracellular Domain | extension of receptor protein within the cytoplasm |
| Signal Transduction | Translation of the hormone message to the interior of the cell with first messenger (hormone) causing a conformational change that triggers a biochem change in the cell cytoplasm, causing a release of the 2nd messenger |
| Transcription | transfer of genetic code information from one kind of nucleic acid to another, especially with reference to the process by which a base sequence of mRNA is synthesized on a template of complementary DNA |
| Translation | Complex process by which mRNA transfer RNA and ribosomes effect the production of protein from amino acids, the specificity of synthesis being controlled by the base sequences of the mRNA. |
| Hormone Effect Time | Steroid hormone initial action on the body is slow (hours or days) but effect is long lasting; protein and peptide hormones act within minutes |
| Biological Activity of Steroid Hormones in a Tissue depends on | local concentration of hormone, number of receptors for hormones that are present, cells can gain or lose receptors, timing, |
| Three endogenous estrogens | estradiol, estriol, and estrone |
| Estradiol Strenth | strongest affinity to receptors |
| Estriol Strength | weak estrogen that binds to estrogen receptor about 10% as well as estradiol |
| Estrone Strength | weaker estrogen that binds to estrogen receptor about 1% as well as estradiol |
| Sex Steroid Binding Globulins | binding proteins only release a certain number of steroid molecules at a time; bound do not effect target cells; released non bound steroid molecules effect target cells; only 2% of free estradiol in blood; availability that is regulated by the concentration of carrier proteins; changes with pregnancy and obesity; |
| Synthetic analogs | molecules synthesized by chemists that are chemically similar to estrogen |
| agonists | stimulate estrogen receptors |
| antagonists | block estrogen receptors |
| estradiol effects | activates all three receptor types; decrease osteoporosis, increase in breast and uterine cancer |
| tamoxifen activates | bone and uterine receptors; decrease osteoporosis and increase uterine cancer |
| raloxifene activates | activates only bone receptors; decreases osteoporosis |
| Melatonin | can cause mild sedative effect; dark exposure increases secretion; light suppresses it; at high enough doses it can inhibit the reproductive gonadal systems; melatonin evels in prepubertal children drop before puberty; involved with circadian rhythems; third eye of the breain- seat of the soul |
| Adenohypopphysis (anterior pituitary gland) made up of | pars distalis; pars intermedia; pars tueralis |
| Cell body | contains a nucleus |
| Dendrites | Extensions of cell that conduct nerve impulses toward cell body |
| Axons | carry information away from cell body |
| Synapse | Site where one neuron connects with another |
| Neurotransmitter | chemical secreted by end of the axon, which travels across synapse and initiates electrochemical changes leading to nerve impulses in next neuron |
| Neurosecretary Neurons | the cell bodoies are in the hypothalamus; axons go through the neurohypophysis; the speed of the nerve impulse is slower than a regular neuron; a lot of neurohormones in the cell bodies; |
| Neurophypophysis | cell bodies of these lie on the hypothalamus in the brain; axons in neurohypophysis; secretory axons release oxytocin and vasopressin |
| effects of oxytocin secreted from neurohypophysis | stimulates contractile cells of the mammary glands so that milk can be ejected from the nipples; causes smooth muscle in uterus to contract to facilitate labor or childbirth |
| effects of vasopressin secreted from neurohypophysis | causes kidney to retain water; causes blood vessels to constrict and blood pressure to rise |
| hormones released from adenohypophysis | FSH, LH, ADH, Thyrotropin, Prolactin, GH, O M L |
| Growth Hormone | large protein that simtulates tissue growth by supporting incoroporation of amino acids into proteins |
| ACTH | polypeptide hormone that stimulates adrenal gland to secrete steroid hormones-- cortisol |
| TSH | stimulates thyroid hormone to synthesize and secrete thyroid hormones-- thyroxine |
| PRL | supports mammary glands in femal to become functional and secrete milk |
| MSH | stimulates production of brown pigment, melanin, which is present in cells called melanophores |
| Opioids | natural pain killers |
| FSH | Stimulates ovaries to produce mature germ cells in their enclosed tissue sacs; stimulates the follicular cells to produce estrogen; stimulates testes to produce sperm; |
| LH | stimulates ovaries to secrete female sex hormones; induces release of egg from ovary; stimulates interstitial cells in the testes to synthesize and secrete androgens |
| Hormone Levels at Puberty | growth hormone is higher amounts; gh and androgens |
| FSH and LH from birth to puberty | Fetus and Neonate: high levels; 1-8: low levels; 9-12: levels rise, first FSH and then LH; LH- pulses need to be ever 1-3 hours and of large amplitude for pubery to occure |
| Pubertal Hormones in Females | sudden surge of LH and lesser FSH results in menarche; first might not cause ovulation, but enough to cause menastruation; within several months of menarche, LH surge is large enough to cause the first ovulation. |
| Estradiol and Estrone role in puberty | Estradiol: from growing follicles in ovary; estrone produced by body fat |
| Estrogen Causes.. | mammary gland developement, bony pelvis growth, subcutaneous fat deposition; growth of external genitalia, growth of vagina, oviduct and uterus |
| adrenarche | first endocrine change during puberty |
| Causes of weak androgens, DHEA, and androstenedione | growth of pubic and axiliary hair; slight lowering of voice; sebaceous gland and acne developement; long bone growth, increase sex drive, weak androgens and converted to testosterone allowing tissues to grow and mature |
| Pubertal Hormones in Males | increase in secretion of LH and FSH in males around 10 years of age; onset of spermatogenesis and rise in tesosterone secretion from testis |
| testicular androgens and adrenal andorgens cause | sex accessory structure growth (seminal vesicles, prostate gland, penis scrotum); secondary sexual characeteristics growth (pubic, axillary, facial hair; larynx growth); retention of nitrogen, Ca, and phophorous which supports bone and muscle growth; penis growth and touch sensitivity enhancement; male sex drive enhancement |
| Where are neurohormones released? | from neurosecretory neurons at the median eminence in the floor of the hypothalamus |
| Where are cell bodies of neurosecretory neurons clustered? | in the Hypophysiotropic area (HTA) of the hypothalamus |
| Hypothalamic-Adenohypophysial Connection | Neurohormones are released at median eminence in hypothalamus and transported to pars distalis of adenohypophysis via the hypothalamo hypophysial portal vascular system |
| Releasing Hormone (RH) | increases output of specific adenohypophysial hormone |
| Release-inhibiting hormone (RIH) | decreases output of specific adenohypophysial hormone |
| Releasing Hormones from Hypothalamus | GnRH, PRH, CRH, RH, GHRH, MSHRH |
| Release Inhibiting Hormones from Hypothalamus | PRIH, GHRIH, MSHRIH |
| GnRH | increases release of RSH and LH from adenohypophysis; neurons in HTA secrete GnRH and axons extend to median to exert their control over pituitary LH and FSH secretion; secreted in pulses every hour or so into the hypophseal portal system; because of this the pituitary releases FSH and LH in pulsatile fashion |
| PRH | increases release of prolacting from adenohypophysis; secreted by hypothalamus |
| PRIH | is secreted by neurosecretory neurosn in the hypophysiotropic area of hypothalamus |
| Negative Feedback | secretion of hormone above a set point cuases a decrease in secretion of pituitary hormone in blood |
| Positive feedback | secretion of a hormone above a set point causes in increase in secretion of pituitary hormone in the blood |
| Regulation of Gonadotropin Secretion Negative Feedback | 1) secretion of steroid sex hormones by the ovaries or testes 2) sex hormones have feedback affects on the systems that control secretion 3) estrogen lower secretion of LH and FSH 4) moderate/ high lower secretion of LH and FSH |
| Gonadostat | Hypothalamus containing control center that monitors levels of estrogen and progesterone s |
| When Estrogen or progesterone levels rise above the set poin the gonadostat signal.... | ignals the hypophysiotropic area to stop secreting GnRH which results in the reduction of secretion of LH and FSH from anterior pituitary; |
| When Estrogen or progesterone levels are below the set point the gonadostat signals... | signals the hypophysiotropic area to increase secretion of GnRH which results in the increased secretion of LH and FSH from the anterior pituitiary |
| Regulation of Gonadotropin Secretion Positive Feedback | high levels of estrogen have a positive feedback by stimulation the GnRH surge center resulting in increased GnRH secretion which increases the release primary of LH and FSH. |
| Gonad Glycoprotein Hormones | Gonads release glycoproteins hormones that influence gonadotropin secretion. |
| inhibin | acts directly on the pituitiary to selectively suppress the secretion of FSH |
| Activin | opposes the action of inhibin and stimulates the release of FSH |
| Follistatin | binds to activin and blocks its action |
| Estrogen affinities | estradiol: strongest affinity to receptor; estriol: weak estrogen that binds to estrogen receptor about 1%0% of estradiol; estrone: weaker estrogen that binds to estrogen receptor about 1% as well as estradiol |
| Progesterone Effects | Negative feedbacks effects on FSH and Lh secretion during luteal phase; supports secretory activity of the uterus during the luteal phase; supports pregnancy; raises the uterine threshold to contractile stimuli during pregnancy; supports breast developement |
| Androgen Effects | tesosterone causes prenatal differenetitaion of the wolffian ducts which are precursors to male seminal vesicles and male sex accessory ducts; causes developement of male secondary sex characteristsics at puberty |
| DHT | causes prenatal differentiation of external genitalia; distribution of male hair distribution; increases size and secretory activity of epididymus, vas deferens, prostrate and seminal vesicles |
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