While a plant-based meal would qualify as vegan (adjective), a person who follows a plant-based (vegan) diet is not necessarily a vegan (noun). For example, someone could follow a plant-based diet but still wear leather and have no moral issue with hunting or killing animals for food.
Ball-and-stick model of cimetidine, the prototypical H 2 -receptor antagonist. The H2 receptor antagonists are a class of drugs used to block the action of histamine on parietal cells (specifically the histamine H2 receptors) in the stomach, decreasing the production of acid by these cells.he H 2 antagonists are competitive antagonists of histamine at the parietal cell H 2 receptor. They suppress the normal secretion of acid by parietal cells and the meal-stimulated secretion of acid.
Efficacy spectrum of receptor ligands. An agonist is a chemical that binds to a receptor and activates the receptor to produce a biological response. Whereas an agonist causes an action, an antagonist blocks the action of the agonist and an inverse agonist causes an action opposite to that of the agonist.ypes of agonists [edit]. Receptors can be activated by either endogenous (such as hormones and neurotransmitters) or exogenous (such as drugs) agonists, resulting in a biological response.