Practical 4: Rat Ileum Flashcards
what are receptors
target molecules to which hormones and neurotransmitters bind in order to exert their effects in the body
what are agonists
molecules that activate receptors, including hormones and neurotransmitters and also some drugs
what are antagonists
molecules that interfere wih the ability of an agonist to activate its receptor
when an agonist binds to its specific receptor what is formed
a reversible agonist receptor complex which then causes a response
what Is a response
a series of biochemical changes inside the cell expressing the receptors culminating in a change in cell behaviour
in the intestinal smooth muscle receptors do they have and what neurotransmitters
muscarinic acetylcholine receptors and acetylcholine with the synthetic analogue methacholine
what is the EC50
the concentration of agonist that produces 50% of the maximum possible response
what does a competitive antagonist compete for
the same binding site on the receptor that is bound by the agonist
atropine
a competitive antagonist
what does krebs solution contain
the same concs of various ions as those found in interstitial fluid in the body
why does krebs solution contain glucose
to supply the cells with fuel for respiration, ensuring that they remain alive for the duration of the practical
why do we only leave the methacholine in contact with the tissue for 30 seconds per dose
to avoid desensitisation
why must u fil the beaker with krebs solution before emptying the bath
so that the tissue doesn’t dry out or the cells will die
for the dose response curve on the rat ileum in the presence and absence of atropine what are the axis
response (g tension) on the y axis and log methacholine on the x axis
what does the graph look like
there is a parallel rightward shift on the curve, which shows that atropine is a competitive antagonist
