how do drugs work Flashcards

1
Q

what is the plasma mebrane

A

a selectively permeable barrier between the extracellular environment and the cytosol

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2
Q

what are the components of the plasma membrane

A

Na+, K+, Ca2+, Cl-, Glucose

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3
Q

is there a similar amount of calcium inside and outside the cell

A

no

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4
Q

is there more calcium inside or outside the cell

A

outside

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5
Q

how do drugs work

A

once they arrive at the proper site of action, they bind to receptors

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6
Q

where are receptors usually located

A

on the outer membrane of cells

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7
Q

what does the binding of drugs to receptor do

A

it can sometimes trigger activation of enzymes located within the cell

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8
Q

what type of proteins are receptors usually

A

integral membrane proteins at the plasma membrane, can also be found inside the cell

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9
Q

what do receptors do

A

recognise and bind to specific chemicals which invokes response

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10
Q

can receptor numbers change

A

yes they can be increased (up-regulation) or decreased (down-regulation)

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11
Q

why would up regulation or down-regulation occur

A

in response to a chronically low or high concentration of the agonist to optimise sensitivity

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12
Q

what two properties do agonists have

A
  1. affinity - strength of binding to receptor
  2. efficacy - intrinsic activity
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13
Q

what does efficacy do

A

induces a conformational change in the receptor and activation of a response

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14
Q

what property does an antagonist have

A

has affinity

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15
Q

what does an antagonist do

A

blocks the receptor

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16
Q

why can’t antagonists activate a response

A

they don’t have efficacy

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17
Q

examples of antagonists

A

anti-histamines, beta-blockers

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18
Q

when does down-regulation occur

A

in response to chronically high concentration of ligand.

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19
Q

what does down-regulation do

A

decreases the sensitivity of the cell response to frequent or intense stimulation

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20
Q

when does up regulation happen

A

in response to very low levels of a ligand

21
Q

what does up regulation do

A

increase sensitivity

22
Q

what underlies disease processes

A

aberrant cellular signalling

23
Q

does the intercellular signal chemical (first messenger) enter the cell

24
Q

what does binding of the SIGNAL chemical to the receptor do

A

initiate a series of chemical changes (activation of intracellular second messenger) in the cell

25
what does signal transduction enable
amplification
26
steps of signal transduction
1. direct opening of ion channels 2. direct activation of an enzyme 3. indirect activation/inactivation of enzyme, indirect opening/closing of ion channel involves a g-protein 4. intracellular second messengers involved include: Cyclic nucleotides (eg cAMP) Inositol triphosphate and diacylglycerol and Ca2+
27
what are 3 G-protein component
1. seven transmembrane receptor where the ligand binds 2. G-protein ('switch' coupling receptor to effector enzyme) 3. effector enzyme
28
what does GTP bound mean
the G protein is on
29
What does GDP bound mean
the G protein is off
30
how does a G protein switch itself on and off
the protein itself is an enzyme which converts GTP to GDP and thereby switches itself on and off
31
what is the first signal following fertilisation
calcium signalling
32
is Ca2+ ever produced or destroyed
no it is moved between compartments
33
what does the effects of Ca2+ depend on
concentration
34
what are the actions of calcium
- activation of specific protein kinases, ion channels - regulation of activity of many enzymes
35
what can Ca2+ channel blockers be used to do
modulate muscle contractions
36
what do Ca2+ release channels do
release Ca2+ into the cytosol in response to an increase in intracellular IP3 or Ca2+
37
what is the functional effect of Ca2+ release channels
contraction, proliferation
38
what are targets for histamine receptors
parietal cells - decreased gastric acid secretion
39
what happens when opioid receptors are targeted
decreased peristalsis, increases tone of anal sphincter (partly via Ca2+ channel blockade)
40
example of drug that targets histamine receptors
ranitidine
41
examples of drugs that targets opioid receptors
loperamide
42
what can cause drug side effects (receptor based)
when enzymes bind to receptors found in more than one place in the body
43
why is there low levels of calcium intracellularly
because calcium is a trigger for many functions
44
what do you need to consider when designing drugs
absorption, distribution, metabolism, excretion (ADME)
45
how do receptors work as second messengers
chemicals enter cells and bind to the receptors which changes the confirmation of that receptor
46
what is the GI tract predominantly made up
smooth muscle
47
how are calcium ions kept low
by storing them in many different areas
48
what is a key factor in triggering relaxation in smooth muscle contraction
nitric oxide