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PHYL2064PHARMACOLOGY
| Question | Answer |
|---|---|
| Pharmacodynamics is? | Action of drugs on living tissues |
| Pharmacokinetics is? | Absorption, distribution, metabolism & excretion of drugs (ADME). |
| Pharmacotherapeutics is? | Use of drugs in treating disease. |
| Define "agonist". | A substance that promotes a receptor mediated biological response often by competing with other substances at the same receptor. |
| The two types of agonist are? | 1. Endogenous (naturally made within the body) 2. Exogenous (man-made compounds introduced to the body) |
| Define "receptor". | A molecular structure or site on the surface of or interior of a cell that binds to substances (such as agonists & antagonists) with specificity. |
| Types of molecules that serve as receptors can be? | Cellular proteins Membrane proteins Nucleic acids Enzymes |
| What are the three major types of receptors ? | 1. Ligand-gated ion channel receptors 2. G-protein coupled receptors 3. Nuclear receptors |
| Outline ligand-gated ion channel receptor process. What is the time-scale? Give an example | The agonist binds with the receptor on the cell membrane. Stimulates the opening of an ion channel. This causes hyper-polarisation or depolarisation of the cell & thus cellular effects. Time taken: milliseconds E.g.: Nicotinic ACh receptor |
| Outline 'G-protein-coupled' receptor process. What is the time scale? Give and example. | Agonist binds with the receptor, stimulating G protein on the inside of the cell. Acts as a second messanger causing a cascade of effects.Can cause sig amplification of the signal. Time- seconds. E.g.: Muscainic ACh receptor |
| Outline 'Nuclear' receptor process (time-scale is hours, e.g. testosterone). | Agonist (hormone) passes though the membrane and binds with receptor inside the cell - becomes hormone receptor complex. HRC enters the nucleus and binds to a specific gene stimulating transcription into mRNA & then translation of mRNA into a new protein. |
| Define "Binding". | Joining of an agonist & a receptor with structural specificity which causes affinity (attraction). Binding is reversible |
| What factors are crucial for binding to occur? | - Charge - Shape - Hydrophobic/Hydrophilic regions |
| What is affinity? | Measure of attraction of agonist to the receptor Affinity = forward reaction/backward reaction |
| What is the equilibrium dissociation constant (kd)? | Measure of ow often receptor & agonist come apart after they bind Reciprocal of affinity kd value is the conc at which 50% of the receptors are bound to the agonist |
| What is the effective concentration for 50% response (EC50) | Physiological representation of kd value |
| Describe the relationship between kd & affinity | Inverse relationship - the smaller the kd value the higher the affinity the drug has for the receptor site |
| Define "Potency" | The amount of drug needed to have a good effect (higher the potency, the higher the affinity and the lower the kd) |
| What happens if the conc of the agonist is higher than EC50? | This means that all of the receptors will be occupied at any given time, leading to greater physiological effects |
| What happens if the agonist is weak? | A higher concentration of the drug will be needed to achieve EC50 The agonist has a lower affinity, meaning it can bind effectivel bt does not fit as well & so comes off more quickly. Thus number of activated receptors is lower |
| What is the intrinsic activity of a drug? | Ability of the drug to activate the second messenger cascade & induce changes in cellular activity. Some drugs have greater intrinsic activity that others. Possible reason for why some drugs are more effective than others |
| Explain what an antagonist is. What are two tpes of antagonist |
Created by:
EmmaCL
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