Flashcards in Essential Pharmacology Deck (11):
What is the basic functions of a receptor?
o Enable specificity
o Evoke an appropriate response
Define what is meant by a receptor
Receptors are proteins that recognise a specific compound or molecule. This can result in the triggering of a massive variety of effects, or in some cases, can inhibit the effects of their proteins and chemicals.
Explain the terms agonists and antagonists
Agonists mimic the normal effect of a receptor
Antagonists block the normal action of a receptor
Describe the relationship between agonist concentration and effect
As we increase the concentration of the agonist molecule, more receptors are occupied by it and so, the effect it has increases. This only works up until a certain point where all of the receptors become saturated and there are no longer any more free ones for the agonist to bind to.
Define the term affinity of a drug for a receptor
The strength of the chemical attraction between the drug and the receptor.
Explain the idea of efficacy of an agonist
How good an agonist is at activating the particular receptor.
Define the sources of intracellular calcium
o From internal stores via calcium triggered release from endoplasmic reticulum
o From outside the cell via ligand-gated or voltage-gated channels
o Via inhibition of Ca2+ transport out of the cell
Describe the processes of transmembrane signalling via receptors
There are a few types of membrane receptors that can signal across membranes.
o Receptors that act as ion channels
o Receptors with intrinsic enzyme activity
o Receptors that interact with JAK kinases
o Receptors that interact with G-Proteins
What are intracellular receptors and what usually binds to them?
Intracellular receptors are receptors located inside the cell rather than on its cell membrane. Classic hormones that use intracellular receptors include lipid soluble molecules such as thyroid and steroid hormones.
Describe G-protein coupled receptors
• 7 transmembrane domains, with the ligand-binding site on one of the extracellular loops.
• Associated with heterotrimeric G proteins made up of Gα, Gβ and Gγ subunits. Upon activation, the subunits dissociate, with the variable Gα subunit and Gβγ carrying out a myriad of functions. Biggest group of receptors.