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50 Cards in this Set
- Front
- Back
Name 4 important drugs to know from this section
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Somatropin
Bromocriptine Cabergoline Octreotide |
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Hormones (+) or (-) second messeger systems and involve intracellular [?] of
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cyclic AMP
Ca2+ Activation of kinases |
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What are the hormones that enter cells called? Where do they bind?
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Steroids
Receptors on the cell membrane |
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Do steroids cause the immediate secretion of hormones?
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No, they regulate the rate of transcription and translation
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3 categories of hormones
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Steroids
Peptides Amines |
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The major steroids
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Adrenal
Sex Calciferols |
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The major peptides
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Hypothalamic releasing factors
Pituitary hormones Insulin and Glucagon Calcitonin Oxytocin, vasopressin, relaxin GI hormones Angiotensin |
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The major amines
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dopamine
epinephrine thyroid hormone |
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How are peptides and catecholamines administered?
Steroids? |
1. Must be parenterally
2. can be oral |
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Negative feedback and examples
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Release of substrate (-) release of hormone
Glucagon/insulin PTH/plasma Ca Aldosterone/plasma Na Glugagon/glucose |
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Example of complex endocrine control
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Hypothalamic-ant. pituitary control of endocrine gland~ ea. step controlled by different hormone
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Examples of hormones with complex control
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TRH/TSH
CRH/ACTH/glucocorticoids GnRH/LH FH/estrogen and progesterone |
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Stucture of hGH (Somatotropin)
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191 a.a.
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Actions of Somatotropin
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+ nitrogen balance (cell takes in more N than it puts out) w/increased protein syn.
Na, K, Ca, P, and Cl retention |
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Difference between hGH and insulin
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GH favors fat as primary sourse of energy, insulin favor sugars
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hGH and diabetics
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hGH has diabetic effect (favors fat metab, not sugar) causing hyperglycemia and ketosis in diabetics (only).
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How do they think GH acts predominantely
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Release of somatomedin C (IGF-1) in growth plates and liver
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Fxn of somatomedin C
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Acts on chondrocytes to stimulate cartilage replication and formation
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Does somatomedin C stimulate fat metab. like hGH?
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No
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What hormone caues hGH secretion? Which (-) secretion?
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1. GHRH (predominant regulator)
2. Somatostatin (SST) |
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How do GHRH and Somatostatin (SST) work?
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Alter adenyl cyclase
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GHRH cascade
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Binds to receptor attached to Gs, activates adneyl cyclase, converts ATP to cAMP, activates kinase, phosphorylates proteins, enhancement of GH synthesis and release
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SST cascade
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Binds receptor, attached to Gi, (-) adenyl cyclase and Ca2+ channels--- inhibits GH release
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Factors that stimulate GH release
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Hypoglycemia
Oral or i.v. amino acids (esp. arginine) Deep sleep Exercise Dopamine agonists |
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Main treatment for hypopituitary dwarfism
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GH or GHRH
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Problem w/using glucocorticoids to suppress immune fxn in children
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Also supresses GH, leads to retarded growth rate and bone age. May never reach full height
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Why did they stop giving hGH extracted from cadavers?
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3 people contracted Creutzfeldt-Jakob dz
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What does recombinant hGH look like? How is it administered?
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Identical (191 aa)
0.1mg/kg 3X/wk or 0.05 mg/kg/day s.c. or i.m. injection |
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Can GHRH be synthesized?
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Yes
*they first isolated it from pancreatic tumors |
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Laron syndrome. Possible treatment
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Hyperpituitary dwarfism- defective GH receptors
Somatomedin C |
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Why has GH been called the fountain of youth?
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Increases muscle mass
Reduces body fat Reduces wrinkling Woo hoo!!! |
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What may GH shots increase the risk of?
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Carpel Tunnel Syndrome
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What is acromegaly? Major cause?
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Hypersecretion of GH in an adult
Pituitary adenoma often Gs is constantly activated |
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Why use bromocriptine to treat acromegaly? Why is this weird?
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This DA agonist parodoxically (-) GH secretion in 50% of pts. w/acromegaly. Normally bromocriptin increase release of GH
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Pts. who respond to bromcriptine usually have what?
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Tumors that secrete GH and Prl.
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New D2 receptor agonist effective in decreasing GH levels
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Cabergoline
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Why can't we use SST to treat acromegaly? Alternative?
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Metabolized too quickly
Octreotide- synthetic SST analog that has longer 1/2 life |
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Administration of octreotide?
Side effects |
i.m. injection once/month
Diarrhea, nausea, abdominal pain (50%) |
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What else does SST inhibit?
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ACTH, TSH, insulin, glucagon, VIP*
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Octreotide can also be called...and used to treat...
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Sandostain
Pancreatic cholera due to xs VIP secretion |
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Problem w/long term treatment of VIP tumors with Octreotide
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Tumors become resistant
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Prl works in concert with what?
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Thyroxine, sex, and adrenal steroids.
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What is the predominant regulator of lactotrophs in the ant. pituitary.
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DA, binds to D2 receptor on lactotroph
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Where in the pituitary is DA released?
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Median eminence
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What enhances the release of Prl? How?
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TRH
Formation of IP3 to increase intracellular Ca2+ |
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How does DA work on lactotrophs?
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binds D2 receptor, activates Gi, (-) adenyl cyclase, opens K and closes Ca channels
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Prolactin secretion in increased by
(7) |
Pregnancy
Suckling Psychic and physical stress Hypoglycemia High dose estrogen DA receptor blockers (chlorpromazine (thorazine), haloperidol) Drugs that deplete DA: reserpine, alpha methyldopa |
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Prl secretion inhibited by...
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DA agonists: l-dopa, bromocriptine, Cabergoline
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Problems from hyperprolactinemia?
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Galactorrhea, ammenorrhea
compression of the optic nerve (bromocriptine makes tumors shrink) |
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When is it safe to take a pt. off thier DA agonist when being treated for hyperprolactinemia?
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Never, tumors recur
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