Test 4 Review Flashcards
neurotransmitters
signaling molecules that have specific receptors
cell signaling
how cells communicate with each other, using neurotransmitters
hydrophilic ligands have receptors located where?
cell surface, because these ligands are water soluble and can’t cross the lipid membrane
hydrophobic ligands have receptors located where?
intracellular, because these ligands are lipid soluble and can penetrate the lipid membrane
synapse
junction between two nerves where chemical signaling happens
4 modes of cell communication
endocrine signaling, neuroendocrine signaling, paracrine signaling, and autocrine signaling
endocrine signaling
the blood is the transporter from one cell to another
neuroendocrine signaling
neuron is taken to the target by blood
paracrine signaling
cells are very close together, and the message is transmitted by interstitial fluid
autocrine signaling
the cell message is returned to the same cell
steps that happen when the receptor is extracellular
- the ligand (1st messenger) attaches to receptor and activates G-proteins
- G-proteins are the middlemen between the receptor and adenylate cyclase enzyme
- adenylate cyclase converts ATP to cAMP
- cAMP (2nd messenger) converts inactive kinase to active kinase, catalyzing the reaction
steps taken when the receptor is intracellular
- lipid soluble ligand penetrates membrane and joins with the receptor (called ligand-receptor complex)
- the complex travels to the nucleus and attaches to the DNA
- DNA produces mRNA, which synthesizes proteins, leading to the cellular response
is the extracellular or intracellular method faster?
extracellular method is faster, and elicits a response faster as a result
3 Types of Signaling
- Agonist activates signaling-drug is the agonist and opens ion channels
- Agonist activates G protein-drug generates a second messenger and activates the signaling (extracellular receptor method)
- Agonist binds to intracellular receptor-transports to the nucleus and uses protein synthesis
which type of signaling do the majority of drugs use?
extracellular receptor method
agonist
initiates same action of neurotransmitter at receptor
full agonist and partial agonist
full-max response
partial-not complete response
antagonist
has affinity for receptor but produces no activity
competitive antagonist
competes with agonist for receptor site and blocks it
noncompetitive antagonist
binds to another part of the receptor to change the shape of the site so the neurotransmitter can’t bind to it
receptor-agonist complex
produces activity (a neurotransmitter bound to a receptor)
receptor-antagonist complex
produces no activity (blocks site or changes shape of site)
phospholipase C inhibitor (PLC)
noncompetitive antagonist that doesn’t affect the actual receptor, it just changes the reaction so that the reaction stops
intensity of drug effect characterized by 3 things:
- affinity
- intrinsic activity
- efficacy
functional antagonist
when 2 drugs oppose each other–you can get the desired result by manipulating how much of the drug you give that increases cAMP activity
-ex) one drug increases cAMP activity, and the other decreases cAMP activity
what happens when cAMP activity is increased?
it converts the inactive kinase enzymes faster resulting in a quicker and better response
chemical antagonist
chemically changes structure of agonist
- used as an antidote
- ex) protamine (weak base) will neutralize an overdoes of heparin (weak acid)
enzyme inhibition
certain drugs can inhibit certain enzymes
-ex) anti-cholinesterase drugs inhibit cholinesterase, resulting in increased acetylcholine levels
cholinesterase
enzyme that breaks down acetylcholine into inactive form
-it relaxes muscles
what kind of person would you give anti-cholinesterase drugs to?
someone with an acetylcholine deficiency that may have muscle paralysis
phosphodiastrase (PDE)
converts cAMP to ATP (active to inactive)
- if it is inhibited it results in increased cAMP levels
- caffeine is something that can inhibit PDE
irreversible enzyme inhibition
some drugs will permanently inhibit enzymes
-ex)COX enzyme allows inflammation production. aspirin inhibits COX enzyme, preventing inflammation
enzyme inhibition receptor steps (red and green diagram on PP)
- empty receptor-ion channel is closed
- GABA binds to the receptor-ion channel opens
- chloride ions enter and make cell more negative
- benzodiazepine enhances the reaction-more chloride ions enter and make you more sleepy
which of the drugs is more potent and why?
drug x is more potent because it produces the same response as drug y but with lower dose
what happens from point A to B on drug x?
receptors are beginning to be filled, the response is not full yet
what happens from point B to C on drug x?
the drug is really beginning to fill the receptors and take effect
what happens from point C to D on drug x?
the receptors begin filling up and becoming oversaturated, response begins to plateau
nonselective drug
drug isn’t “picky,” it will act on a variety of receptors
potency
amount of drug required to produce the desired response
therapeutic index
relationship between the effective dose and lethal dose
- narrow margin: unsafe, effective and lethal doses are more similar
- wide margin: safe, effective and lethal doses are far apart
