Wokring With Tables And Graphs Flashcards
What is present in a good graph ?
Axes correctly labelled Appropriate scale Broken scales must be indicated Only put lines on if the relationship between x and y is k own Descriptive legend
What is present in a good table ?
Accurate title Labelled columns and rows with units Data to a suitable level of accuracy Describe legend below showing any statistical treat,net Simple enough to understand
In drug-concentration curves what is characteristic of agonists ?
They are able to produce a graded concentration response relationship - as the concentration of the agonist increases the magnitude of the response increases but this is not linear
What is the shape of a drug concentration curve ?
A hyperbola
Why are most agonist-concentration graphs plotted as logarithmic graphs ?
It prevents clumping of data occurring when the concentrations range is large
Makes the graph become s shaped with a well defined linear region
What is the threshold region of a log-concentration response curve ?
Minimum concentration to produce a quantifiable response
What is the linear region of a log-concentration response curve ?
It is the middle region which produces large changes in response to small increments in concentration
This portion is parallel for drugs which produce an effect at the same mechanism but they will have different potencies
What is the maximum response in a log-concentration response curve ?
It is the finite capacity which the biological system can respond to the drug
What is the maximum response dependent upon ?
Ability of the agonist to activate the receptor
Capacity of the system to convert receptor stimulus into a measurable response
What is the EC50?
It is the concentration of agonist which gives a 50% response
What is the purpose of concentration-response curves ?
Used to measure drug activity or selectivity of a biological system
Enables construction of models of drugs actions for comparison
What 2 basic properties can be determined by concentration-response curves ?
Potency and intrinsic activity
What is potency ?
It is a measure of the concentration of drug needed to elicit a response
What is intrinsic activity ?
Measure of the ability of a drug to elicit a response when it occupies its receptor
Full agonists which have intrinsic activity of 1
Partial agonists which have intrinsic activity <1
What is the pEC50/pD2?
Negative log concentration of the EC50
What happens to the concentration response curve when an antagonist is applied ?
It shifts the curve to the right
What is competitive surmountable antagonism ?
Shifts concentration response curve to the right in a parallel manner and max response is unchanged
What is the extent of displacement of an agonist by an antagonist dependent upon ?
Concentration of antagonist present
Strength of binding to the receptor
With competitive surmountable antagonism the parallel displacement can be measured by ratios of what ?
The EC50s
Ec50 without antagonist and ec50 with antagonist
What is the ec50 ratio equal to ?
[B]/Kb
What is the Kb?
Dissociation constant of the antagonist
As it increases the dissociation from the receptor decreases
Antagonists with high affinity have small Kb
How is Kb calculated ?
By plotting log(A’/A-1) vs log[B]
If you get a straight slope of 1 the x-axis intercept is -logKb
Schild plot
What is a schild plot ?
It is used to determine whether an antagonist is competitive or not
Schild plots with a linear slope of 1 and both the x and y intercepts are equal indicate a competitive antagonist
