Pharamcodynamics Flashcards
Define pharmacodynamics.
Is what the drug does to the body and how the body responds.
Name the four ways drugs work.
- Replace missing chemicals or acts as substitutes.
- Stimulate particular cell activities.
- Slow down or inhibit particular activities.
- Interfere with the function of the foreign cells.
Name the types of proteins drugs bind to exert their effects on the body.
- Receptors
- Enzymes
- Ion channels
- Carrier molecules
Define the term affinity.
The ability to bind to a receptor.
What is the collective name for a chemical that binds to a receptor.
Ligand
Describe what it means by lock and key.
A receptor molecule with a specific shape or three dimensional structure and only substances that fit precisely can interact with it.
Identify some drugs that mimic naturally occurring substances produced in the body.
Morphine
Phenylephrine
Contraceptive pill
Define the term efficacy in terms of pharmacodynamics.
It is the measure of the bound ligand to activate a response.
Define the term agonist.
The drug has the same effect on the receptors as does the natural substance that normally binds to the receptors.
Define the term antagonist.
The bound drug blocks the binding sites of the natural substance and so prevents its effects. (Plastic plug cover).
Describe what a competitive antagonist is.
It is the most common and important type of antagonism. It competes with the agonist for the agonist binding site on the receptor. Because the two are in competition, increasing the agonist concentration can overcome the blocking effect and restore the response.
However, the competitive antagonist forms strong bonds to the agonist site and therefore this block cannot be overcome.
Describe what a non-competitive antagonist is for.
They bind to a site other than the agonist binding site. They cause a conformational change in the receptor which reduces the ability of the agonist to bind to its binding site. This reduces the response to the agonist.
Describe Alpha-receptors.
They are associated mainly with increased contractibility of vascular smooth muscle and intestinal relaxation.
Describe Beta-receptors.
They are associated with vasodilation and relaxation of non-intestinal smooth muscle and cardiac stimulation.
Define the term enzyme.
A protein which acts as a biological catalyst.
Give an example of an irreversible enzyme inhibitor which used in a clinic.
Ibuprofen
NSAISs are examples of drugs that block the activity of an enzyme. What does NSAIDs inhibit?
Cyclo-oxygenase (COX)
What are Acetylcholinesterase used for?
It is a neurotransmitter that helps with memory and thinking.
People with Alzheimer’s disease use this to stabilise or improve their symptoms.
How does Acetylcholinesterase stabilise symptoms of Alzheimer’s?
It breaks down acetylcholine in the synapse. By inhibiting the breakdown of the acetylcholine more of this neurotransmitter would remain in the synapse and enhance memory.
Name the ions that interfere with the movement of ions across cell membranes.
Sodium,calcium and potassium.
Give an example of a common drug which affects ion channels.
Calcium channel blocker ( Often used to treat hypertension or angina).
Describe what calcium channel blockers does.
They act as vasodilators by blocking the intracelluar calcium required for the contraction of arteriole smooth muscle.
This vasodilation causes a reduction in peripheral vascular resistance (PVR) leading to reduced blood pressure.
Name a drug that affects ion channels (modulators).
Benzodiazepines acts as modulators of the GABAa receptor.
Name a drug that affects transport carriers/proteins.
SSRIs which prevent the reuptake of serotonin from the synaptic cleft back into the pre-synaptic neurone.
One of the actions of serotonin in the CNS is as mood enhancer.
What are sodium channels vital for?
They are vital to the propagation of the action potential along nerve cells.
They block the sensation of pain.
What do potassium channel blockers prevent?
Amiodarone-used to prevent arrhythmias.
What do potassium channels openers responsible for?
They are responsible to treat hypertension or angina as they relax smooth muscle causing vasodilation.
