Nucleus of a cell: the largest organelle. Surrounded by a double membrane called the nuclear envelope consisting of nuclear pores. These pores regulate what goes in and out of the nucleus. A bulk of the interior of the nucleus is made up of nucleoplasm which contains chromatin and nucleoli.
A receptor antagonist is a type of receptor ligand or drug that blocks or dampens agonist-mediated responses rather than provoking a biological response itself upon binding to a receptor.They are sometimes called blockers; examples include alpha blockers, beta blockers, and calcium channel blockers.n antagonist that binds to the active site of a receptor is said to be non-competitive if the bond between the active site and the antagonist is irreversible or nearly so.
A competitive antagonist, if present, will compete with agonist to bind to a receptor, without activating it â but in such a way to prevent the binding of the agonist. That is, the agonist and antagonist are in competition to bind to a receptor since the receptor can only bind to one of them at a time. At any agonist concentration, there will be reduced receptor occupancy by agonist in the presence of antagonist.