An antagonist binds to a receptor and prevents a natural compound or drug from having an effect on the receptor.
A second messenger.
The biochemical and physiological effects of drugs and their mechanisms of action.
It leads to a response.
It involves substances that bind to receptors without activating them, preventing agonist binding.
It represents the logarithmic scale of drug concentration in relation to response.
It binds to a different site on the receptor, exerting its effect through that site.
No, no drugs are completely specific; their actions are dose dependent.
Signal specificity.
By diffusion.
Protein molecules that recognize and respond to endogenous chemical signals.
Agonists and antagonists.
Ligand binding domain and message propagation domain (effector domain).
Individual classes of drugs bind only to certain targets, and individual targets recognize only certain classes of drugs.
It forms a drug-receptor (DR) complex, which can lead to a response if the drug is an agonist.
Signal amplification.
Inactivating the agonist, such as an antacid reacting with acidic drugs.
Antagonists produce effects opposite to those of an agonist (negative efficacy).
It competes for the same binding site as the agonist.
Affinity describes the ability or tendency of a drug to bind to its receptor to form a complex.
Receptors, enzymes, carrier molecules (transporters), and ion channels.
Cyclic AMP (cAMP).
Antagonists have zero efficacy (intrinsic activity = 0), meaning no response is achieved by their binding.
The maximal effect a drug can produce.
Yes, it can be either reversible or irreversible.
They are protein targets for drug binding that act within the cell.
The maximal response a drug produces at full receptor occupation.
Calcium ions (Ca2+).
The receptor is functionally activated.
A type of protein target for drug binding.
Receptors located inside the cell that bind to ligands.
The dose required to produce a certain response.
On cell surfaces, within the cell membrane, and inside the cells.
Irreversible and reversible.
Receptors linked to enzymes.
Key and Lock theory.
Cyclic GMP (cGMP).
The dose at which 50% of the maximal effect is observed.
Ligand-gated ion channel receptors.
It is where the drug binds selectively via chemical bonds.
A type of receptor that is a protein target for drug binding, involved in cellular signaling.
A full agonist has affinity and efficacy, binds to a receptor, and elicits a maximal response (100%).
Potency is inversely related to the dose (drug concentration).
When two substances act to oppose each other's effects.
A type of physiological receptor that interacts with G-proteins.
It transduces and propagates extracellular signals into an intracellular amplified response.
It results in no response but prevents the response of the agonist.
Small, non-protein, water-soluble molecules or ions involved in signal transduction.
A partial agonist has affinity and some efficacy, binds to a receptor, but never produces a maximal effect (< 100%).
The magnitude of the response is proportional to the number (fraction) of receptors occupied by drug molecules.
It is graded or dose-dependent.
Altering the way the body handles another drug, affecting absorption, metabolism, or excretion.
It acts as a second messenger.
Competitive and non-competitive antagonism.
An antagonist binds to a receptor but does not activate it, preventing the response of an agonist.
The receptor is functionally silent.
Channel blockers.
Efficacy (or intrinsic activity) is the ability of a bound drug to change the receptor in a way that produces an effect.
Channels that open in response to the binding of a ligand, serving as a protein target for drugs.
Efficacy increases as a function of concentration.
