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32 Cards in this Set
- Front
- Back
Endocrine System
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-regulatory system
-involved in maintaining homeostasis -endocrine + nervous system = 2 regulatory systems in the body |
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Difference b/w Hormone and Neurotransmitter
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Neurotransmitter - released from axonal terminals into synaptic cleft
hormone - released from endocrine glands into extracellular fluid - interstitial fluid, or blood |
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Hormones
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released from endocrine glands in response to changes in the environment(internal or external) termed stimuli
-these changes of stimuli lead to homeostatic imbalances and hormones are released to correct these stimuli --hormones work through negative feedback mechanism |
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Hormone receptor characteristics
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1) all hormone receptors are proteins - globular
2) they bind to hormones in a reversible manner 3) they bind to specific hormones w/ a high affinity and specificity - for their specific receptors 4) 2 families of hormone receptors - depends on calsses of hormones they bind --cell surface receptors(membrane receptors) --intracellular receptors ----cytoplasmic receptors ----nuclear receptors |
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Polar Hormones
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biogenic amine, peptide/protein/glycoprotein hormones bind to cell surface receptors - transmembrane receptors
-span the plasma membrane and are exposed to the interior/exterior of the membrane -polar hormones can't cross lipid bilayer --hence cell surface receptors |
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Intracellular receptors
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located in cytoplasm(cytoplasmic receptors) or in nucleus(nuclear receptors)
-steroid hormones derived from lipid cholesterol are all nonpolar --can cross lipid bilayer to bind to intracellular receptors --all steroid hormone receptors are intracellular |
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How Hormones Interact w/ their target cells
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1)classical endocrine interaction
2)paracrine interaction 3)justacrine interaction 4)autocrine interaction |
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Classical endocrine interaction
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gland releases hormone into bloodstream which transports the hormone to the target cells located a distance away
-ex. thyroid stimulationg hormone released from anterior pituitary travels through blood stream to reach its target organ - thyroid organ TSH stimulates thyroid gland to secrete 2 thyroid hormones - T3 n T4 |
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Paracrine Interaction
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the endocrine cells releasing the hormones are neighboring cells to the target cells -> endocrine cells + target cells in same organ
-ex. in pancreas - both a pancreatic cells(secrete glucogon) and B pancreatic cells(secrete insulin) when insulin is released one of the action of it is to bind to insulin receptors on the neighboring a cells to inhibit glucogon release Insulin acts to stimulate cellular uptake of glucose from blood, glucogon acts to stimulate release of glucose from cells into blood - when released it binds to receptors on B cells to inhibit insulin release |
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Justacrine interaction
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the endocrine cells and target cells in close contact - juxtaposed
--the hormone binds to receptors on target cells w/o first getting into extracellular fluid ex. in closely packed cells - placenta -> fetal-maternal exchange unit |
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Autocrine interaction
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the endocrine cells releasing the hormone also acts as target cells for the hormone
ex. B pancreatic cells release insulin after meals when blood glucose levels are high(hyperglycemia) - insulin binds to insulin receptors on B cells to stimulate more release of insulin |
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Hormonal Interrelationship
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how hormones affect other hormones release in the body
5 types 1)agonism 2)antagonism 3)permissiveness 4)cooperativity 5)synergism |
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Agonism
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a hormone released binds to the receptors of another hormone to stimulate the biological effects of the absent hormone
ex. hA binds to hB receptors -> effects of hB |
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Antagonism
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a hormone released binds to the receptors of another hormone, blocking that hormone from accessing its own receptors
-biological effects of blocked hormone NOT observed |
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Permissiveness
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a hormone released binds to its own receptors and elicits its biological effects which include stimulation of another hormone - increase in release or increase in receptors of that hormone
ex. hA -> ^release of hB and ^ #receptors of hB hence hA increases biological effects of hB |
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Cooperativity
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at least 2 hormones work in tandem to bring about a desired biological effect
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Synergism
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a group of hormones work together to bring about a biological response greater than the sum of thei individual effects
ex. hA -> 2 units of bio effect hB -> 3 units hC -> 4 units hA+B+C = 20 units instead of 9 |
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Hypothalamus
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"master gland" - the 9 hormones produced by it directly or indirectly affect the actions/release of other hormones
-9 hormones -antidiuretic hormone, oxytocin, growth hormone releasing hormone, growth hormone inhibiting hormone, prolactin releasing hormone, prolactin inhibiting hormone, corticotropic releasing hormone, gonadotropic releasing hormone, thyrotropic releasing hormone |
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Antidiuretic Hormone
Oxytocin |
ADH = vasopressin
These 2 are delivered via hypothalamic hypophyseal tract by anterograde transport to the posterior pituitary for storage and release in response to appropriate stimuli |
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Growth hormone releasing hormone
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stimulates cells in anterior pituitary to secrete growth hormone
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Growth hormone inhibiting hormone
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stimulates same cells in anterior pituitary to inhibit growth hormone release - somatostatic
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Prolactin releasing hormone
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stimulates cells in the anterior pituitary to secrete prolactin - stimulates milk production in breasts
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prolactin inhibiting hormone
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dopamin - inhibits same cells from secreting prolactin
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corticotropic releasing hormone
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stimulates cells in anterior pituitary to produce the hormone adrenocorticotropic hormone - stimulates the adrenal cortex to secrete the glucocorticoids - these regulate glucose levels - major one in humans is cortisol
--overproduction of cortisol -> cushings syndrome |
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Gonadotropic releasing hormone
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stimulates cells in the anterior pituitary to secrete gonadotropics
-follicle stimulating hormone -luteinizing hormone --these stimulate the gonads(testes/ovaries) to produce sex steroid hormones ----testosterone in males, estrogen/progesterone in females ------required for the formation of sex cells - gametes -- sperm in males, ova in females |
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Thyrotropic releasing hormone
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stimulates cells in the anterior pituitary to produce thyroid stimulating hormone - stimulates thyroid gland to produce 2 thyroid hormones T3, T4
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negative feedback
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the biological effects of hormones negate/eliminate the stimuli that caused the release of the hormones
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stimuli for hormone release
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3 types
-humoral -hormonal -neural |
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Humoral stimuli
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changes in the levels of chemicals in the body’s humors ( bodily fluids) stimulate endocrine glands to release hormones
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Neural Stimuli
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activation of the nervous system stimulates endocrine glands to release hormones
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Hormonal stimuli
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released hormones stimulate endocrine glands to release other hormones
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Posterior Pituitary gland
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may/may not be an endocrine gland - based of definition of endocrine gland
-if they need to produce the hormones then NO -if they need to release hormones - then YES |