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60 Cards in this Set
- Front
- Back
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Vasodilator drugs were created for heart issues but were not that great. What did they see when men used vasodilators and what is it used for now?
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Males reported increase in erection, so they now are for treating erectile dysfunction.
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The next family of receptors are intracellular receptors, where are they located?
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Some are located in the cytoplasm, and some are found in the nucleus.
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Upon binding of the hormone and being activated, intracellular receptors eventually bind to what?
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eventually bind to DNA and alter transcription.
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What are the three domains of intracellular receptors?
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Transactivation domain, DNA binding domain, and ligand- binding Domain
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Transactivation domain of intracellular receptors are located where?
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Are usually far from the DNA binding domain and ligand-binding domain.
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DNA binding domain of intracellular receptors contain what and do what?
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Contain Zinc fingers, which are DNA proteins that bind to dNA and dimerize so that the receptors, when activated, can be transported to the nucleus and affect transcription.
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What are Ligand-binding domain of intracellular receptors, hydrophilic or hydrophobic and why?
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Since the hormones that use these receptors are hydrophobic, the ligand-binding domain is also hydrophobic.
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There are heat shock proteins (HSPs) in the rough ER that do what?
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They bind exposed hydrophobic sites of the receptors or other hydrophobic proteins that have just been synthesized and function in preventing aggregation.
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When to HSPs bind to the ligand-binding domain?
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In the absence of the hormone to prevent aggregation.
ex. When you fry an egg, the egg proteins are unfolded and will aggregate to form the white part of the egg. |
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HSPs are located in the RT and function in what?
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In assisting other proteins just synthesized in the ER to fold correctly.
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What is the difference between and agonist and and antagonist?
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Agonists mimic the effect of a molecule and antagonists inhibit the effect of a molecule.
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what are antagonists used for?
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In the treatment of certain breast cancers that are sensitive to estrogen.
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Some responses upon hormone binding are very fast, give an example.
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Steroid hormones, it is thought that there are membrane receptors that involved with this.
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The pituitary gland (hypophysis) is housed in the sphenoid bone of the skull and consist of two different portions which are?
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the Anterior pituitary and Posterior pituitary.
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What is the master gland called?
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Anterior pituitary
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What are some details of the Anterior pituitary.
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-Contains several endocrine cells that secrete 6 hormones
-Activity is regulated by the hypothalamus -cells of the anterior pituitary can develop benign tumors |
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What would result if cells of the anterior pituitary had benign tumors?
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-If they are functional tumors, they will result in over-secretion of hormones which can have adverse effects
-If the anterior pituitary increases in size due to tumor formation, the optic chiasm, area in the brian that carries visual information from the optic nerve from the eyes to the visual cortex, will be squeezed, which can cause loss of visual fields. |
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Describe the Posterior Pituitary?
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-Does not have any endocrine cells.
-Has bundles of axons from neurons of the hypothalamus |
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The posterior pituitary has secretory vesicles that release what 2 hormones?
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Vasopressin (ADH) and Oxytocin, synthesized in the hypothalamus upon activation.
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The hypothalamus secretes several releasing-hormones, these hormones regulate what?
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regulate the secretion of the 6 hormones of the anterior pituitary
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A lot of the secretion of the 6 hormones of the anterior pituitary gland from the hypothalamus are stimulatory. Give an example.
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TRH stimulates TSH release, which stimulates the thyroid to release thyroid hormones.
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what are the inhibitory hormones that are the main regulators?
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PIH (dopamine) prevents release of prolactin, and GHIH (somatostatin) prevents release of GH.
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What are trophic hormones?
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Are hormones secreted by the anterior pituitary that stimulate the secretion/function of glands.
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what are the four trophic hormones from the anterior pituitary?
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1. TSH (stimulates the thyroid gland to take up iodine and to synthesize/secrete thyroid hormone.)
2. ACTH ( stimulate adrenal cortex) 3. FSH and LH (stimulate ovaries or testes) |
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The regulation of ACTH, FSH, LH, and TSH secretions is by what kind of feedback loop?
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by a negative feedback loop of the final hormones.
ex. thyroid hormones would inhibit the anterior pituitary gland and hypothalamus by a short feedback loop. |
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The negative feedback mechanism is useful for diagnosis/treatment, give an example.
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If thyroid hormones are not being secreted, this will increase TRH and TSH secretion. Likewise, if there is high secretion of thyroid hormone secretion, there will be low secretion of TRH and TSH.
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What influences the secretion of the four tropic hormones?
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Things like appetite, body temperature, circadian rhythms, emotion, psychological issues (stress etc...)
*In the case of GH secretion regulation, there will be several types of metabolic and circadian regulation. |
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What is prolactin secreted by?
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secreted by lactotrophs, cells in the anterior pituitary.
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Prolactin's main target is the breast and it does what?
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-Stimulates milk production
-Lactotrophs are inhibited by dopamine (main regulation) and stimulated by PRH |
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Tumors of lactotrophs are the most common among young women and can be very small. What are symptoms of such a problem?
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-One of the first symptoms would be issues with periods because periods are initiated by GnRH causing release of FSH/LH
-can be absent/alteration of menstrual periods -Can be treated successfully with dopamine agonists to block their receptors. |
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Breast normally do not produce milk except after pregnancy, why?
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During pregnancy, there is an increase in prolactin secretion to begin to produce milk bust also during pregnancy there is also an increase in estrogen, which prevents milk production.
*after birth, estrogen/progesterone concentrations drop drastically, allowing prolactin stimulate breast for milk production. |
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What is prolactin secretion stimulated by?
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suckling of the nipple which inhibits dopamine secretion.
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what does prolactin inhibit?
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it inhibits the responses of the anterior pituitary to GnRH, preventing ovulation.
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What two hormones have cytokine receptors?
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GH and prolactin.
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The hypothalamus will release GHRH and GHIH (somatostatin) in pulses when is GH secretion increased?
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during sleep at night
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GH has metabolic functions as well as growth effects, which usually happens when there is a deficiency in protein intake. What are the metabolic functions?
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-Increase protein synthesis
-Decrease proteolysis (protein metabolism) -Increase lipid breakdown and metabolism -Energy utilization -Increase gluconeogenesis (glucose synthesis) -Increase insulin resistance. |
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What is GH secretion stimulated by?
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-The hypothalamus releases GHRH to stimulate GH release
-Ghrelin is a hormone released by the stomach that also stimulates GH secretion -Several AA, especially Arg, stimulate GH release and GH will in turn increase protein synthesis. |
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What does Ghrelin stimulate besides the secretion of GH?
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Appetite- an empty stomach stimulates release and a full stomach inhibits release.
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Hypoglycemia is the decrease in blood glucose and it stimulates GH secretion, how?
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The functions of GH increases gluconeogenesis and fat breakdown.
If there is a suspicion of lack of GH, one can be administered a lot of insulin to lower blood glucose, which can stimulate GH release. |
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What is GH secretion inhibited by?
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-The hypothalamus also releases somatostatin to inhibit GH release (do it through the Gi pathway)
-Hyperglycemia, increase in [blood glucose] |
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Overproduction of GH results in what?
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pituitary tumor.
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what is responsible for many of the growth effects on target tissues of GH in childhood and affects all organs?
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IGF1
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What is epiphyses?
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shaft of the bone (diaphysis) and on each end of the bone
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What separates the diaphysis and epiphysis during the growing years?
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growth cartilage, which contain receptors for IGF-1
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At early part of adolescence, there is a growth spurt because of what?
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there are other hormones involved, like the androgens and thyroid hormones.
*Happens earlier in females, and one stops growing when all the growth cartilage in bone has become bone. |
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What is the process of linear growth?
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Upon action of hormone, cells in the growth cartilage (called epiphyseal plates) will divide and multiply and then eventually differentiate into bone and add to the shaft of the bone.
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What is the cause of Laron Dwarfism (short stature)?
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Lack of function of GH receptors, due to mutations in the receptors themselves, which are tyrosine kinase receptors.
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Lack of GH receptors results in what?
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Results in dwarfism because the body cannot grow.
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Too little secretion of GH can be a cause of what?
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-pituitary: GH is not being released
-Hypothalamus: GHRH is not being released |
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Too much secretion of GH can can cause what two diseases?
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-Gigantism- Increased GH secretion during childhood (causes increase in linear growth.)
-Acromegaly- common cause is a tumor in the somatotrophs, cells that secrete GH in the pituitary, which aren't seen till after puberty. |
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What is the difference between acromegaly and gigantism?
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in acromegaly it happens after adolescence and growth cartilage has calcified so there is no linear growth, but growth of organs
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What are the two main effects of ADH?
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-decrease the volume by reabsorbing water in the kidney
-cause vasoconstriction and increase in blood pressure. |
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What is the secretion of ADH sensitive to?
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osmolarity.
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Hypothalamus also receives input from stretch receptors that detect volume and baroreceptors, receptors that detect pressure, how does this happen?
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BV drops and causes a drop in BP, which stimulates baroreceptors and ultimately results in ADH secretion to increase BP.
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How does ADH enforce water reabsorption in the collecting duct specifically?
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By inserting aquaporins, water channels, in the cells.
-ADH binds to receptors in the collecting duct cell and triggers exocytosis of secretory vesicles containing aquaporins 2 channels. |
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How does ADH induce thirst
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If the osmolarity incerases, meaning everything is concentrated, this stimulates ADH secretion to add aquaporins and stimulate reabsorption of H20
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What can be causes of abnormalities of ADH?
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1. Can be caused by a problem with the hypothalamus or pituitary stalk(ADH is not traveling down the axon properly)
2. Be a problem with receptors 3. Can be a problem with transduction mechanism of ADH |
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What are the symptoms of people with ADH deficiency (Diabetes Insipidus) urinate high volumes of dilute urine (polyuria)?
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1. have to go to the bathroom very often
2. have low BP 3. Fatigued easily 4. Be very thirsty all the time (polydipsia) 5. Dehydration |
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People with over excess of ADH secretion causes what?
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dilution of extracellular space specifically sodium.
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People with over excess of ADH secretion also cause hyponatremia which is?
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a lack of extracellular sodium due to high water reabsorption, which is problematic for conduction of action potentials.
* this results in a raise of threshold for excitation and also requires a stronger stimuli. Action potentials are smaller and conducted slowly. |
