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.
Agonists and Antagonists. Agonists are chemicals that mimic the action of a particular neurotransmitter. They bind to receptors and generate postsynaptic potentials. Antagonists are chemicals that block the action of a particular neurotransmitter. They bind to receptors but canât produce postsynaptic potentials.Because they occupy the receptor site, they prevent neurotransmitters from acting.eurons, Hormones, and the Brain. 1  The Nervous System. 2  Neurons: Cells of the Nervous System. 3  Neurotransmitters. 4  Studying the Brain. 5  Structure and Functions of the Brain. 6  The Endocrine System. 7  Quick Review. 8  Review Questions. 9  Neurons, Hormones, and the Brain Quiz. 10  How to Cite This SparkNote.