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31 Cards in this Set
- Front
- Back
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Differentiate berween endocrine autocrine and paracrine
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Endocrine - hormone acts on cells in distance
Paracrine - hormone acts on cells nearby Autocrine - hormone acts on cell from which its secreted |
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2 types of membrane receptors
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Metabotropic-changes activity of metabolic enzymes
Ionotropic- let ions into or out of cell, associated with depolarization, classical synaptic transmission |
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How does cocaine act on cell
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Blocks dopamine reuptake and leads to overexcitability of cells
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Describe steps of synapse
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1.Depolarization opens voltage gated Ca channel
2.Ca leads to vesicle fusion and release of NT 3. NT diffuses over synaptic cleft and binds to ligand gated channel 4.NT also acts on G protein linked receptor 5.NT is reuptaken |
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How is Ach degraded
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by enzyme Ach esterase
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How do cells become polarized
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Na/K pump gets 3 Na out, 2 K in, this creates high Na outside, high K inside
-creates NEGATIVE charge inside |
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How does nicotine act on cell
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Overstimulates N1 and N2 receptors
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How does tetrodotoxin act on cell
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Block voltage gated sodium channels
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How does boulinum toxin act on cell
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Botulinum toxin blocks Ach release, leads to paralysis
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Describe myasthenia gravis
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Autoimmune disorder where nicotinic type I (N1) Ach receptors are attacked and destroyed
Number of N1 receptors is decreased and this causes decrease in muscle response to Ach |
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How is myasthenia gravis treated
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With drugs that inactivate Ach esterase, which will prevent degrading of Ach and increase its half life
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Explain cascade of events involving trimeric g proteins
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1. Hormone or NT binds serpentine receptor (heptahelical receptor)
2.Allosteric changes in serpentine proteins induce G protein to dissociate into alpha subunit and dimeric beta gamma subunit, alpha subunit kicks out GDP and binds GTP 3. Activated alpha subunit is free to drift until it encounters target enzyme, so alpha subunit stays active for limited time and then dissociates |
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What does cAMP activate
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protein kinase A
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What does cAMP do
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cAMP activates PKA which is a Ser/Thr kinase that phosphorylates numerour target enzymes. One of the many targets is CREB, which is a transcription activator
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Which amino acids get phosphorylates
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Tyrosine
Threonine Serine Histidine |
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Describe action of cholera toxin
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Prevents G alpha s from hydrolyzing ATP
Adenylated g protein sabotages ability of g protein to turn GTP into GDP, so GTP cant turn off Result - INCREASED cAMP (mostly in intestinal cells) |
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Desribe action of pertussis toxin
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Prevents G alpha i from binding GTP, results in increased cAMP
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Describe action of beta blockers
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Prevents activation of G alpha s , results in decreased cAMP
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What activates PLC
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G alpha q
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PIP2 cleavage by phospholypase C yields ...
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DAG and IP3
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PIP 2 phosphorylation leads to
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PIP3 which activated PKB
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Which toxin is agonist for PKC
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Phorbol ester
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What is the effect of NO
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Vasodilataion
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How does nitroglycerine work
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Slowly breaks to NO which causes vasodilation and turned off when oxidized to nitrate
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How does Viagra work
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Specific to isoform of cyclic nucleotide found in penis
Inhibits cyclic GMP phosphodiesterase |
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What does caffeine do
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Inhibits phosphodiesterase, thus increasing cAMP in cells
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Phospholipase C associates with what subunit
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Beta gamma subunit
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What does DAG do
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Stays with membrane
Stimulates PKC to phosphorylate Ca dependent targets |
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Phorbol ester
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Mimicks DAG, activates PKC, can lead to cancer
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What does IP3 do
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Goes to ER, stimulates release of Ca, which activates PKC, which in turn activates Ca calmodulin kinase
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Amplification of signaling
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Very low concentration of hormone has large intracellular effect
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