test 2 part 3 Flashcards
1
Q
Pharmacodynamics
A
- The actions of a drug on the body
- The influence of drug concentrations on the magnitude of the response
- Signal Transduction
- Alterations in biochemical and/or molecular activity of a cell initiated by the drug-receptor complex
2
Q
what is a Drug
A
- Any substance that brings about a change in biologic function through its chemical actions
- Must have appropriate
- Size- small are less likely to be selective (can fit a lot of different receptors)
- Electrical charge
- Shape
- More than half of all drugs are chiral molecules
- Atomic composition
3
Q
Drug Electrical Charge: Drug-Receptor Bonds
A
- Covalent (electron sharing)
- Very strong
- Not reversible
- Electrostatic
- More common than covalent
- Vary from strong to weaker hydrogen bonds to van der Waals forces
- Hydrophobic (most common)
- Relatively weak
- Important in highly lipid soluble drugs within lipids of cell membranes
- Drugs that bind through weak bonds are generally more selective than drugs that bind through very strong bonds
4
Q
Drug Shape: Racemic Mixtures
A
- Majority of drugs available as racemic mixtures (2 different isomers)
- Potency and duration of action different in many cases
5
Q
Receptor
A
• Any biologic molecule to which a drug binds and produces a measurable response • Enzymes • Nucleic acids • Structural proteins -1. needs to be selective for a ligand -2. pharmacological response -needs both to be a receptor
6
Q
albumin as a binding site
A
- inert binding site
- does not have a direct biological effect
- drug binding to albumin does effect the volume of distribution and the amount of free drug in the bloodstream
7
Q
Signal Transduction
A
- unoccupied receptor does not influence intracellular processes
- receptor with bound agonist is activated. It has altered physical and chemical properties, which leads to interaction with cellular molecules to cause a biologic response
8
Q
The Drug-Receptor Complex
A
- Cells have many types of receptors
- Specific for particular agonist
- Produce unique response once activated
- Magnitude of response proportional to number of drug-receptor complexes
- Most receptors named for the type of agonist it interacts best with
- Not all drugs exert their effect through receptors
9
Q
Receptor States
A
- Inactive (R)
- Active (R*)
- Reversible equilibrium usually favoring inactive state unless ligand bound to it
- Equilibrium shifts to R* when agonist binds
- Magnitude of effect directly related to fraction of R*
10
Q
Major Receptor Families
A
- Ligand-gated ion channels
- G protein-coupled receptors
- Enzyme-linked receptors
- Intracellular receptors
11
Q
Ligand-gated Ion Channels
A
- Ligand binding site on extracellular portion
- Opens channel for a few milliseconds
- Ions then move in or out
12
Q
G Protein-coupled Receptors
A
- unoccupied receptor does not interact with G protein
- Occupied receptor changes shape and interacts with G protein. G protein releases GDP and binds GTP
- Alpha subunit of G protein dissociates and activates adenylyl cyclase
- When hormone is no longer present, the receptor reverts to its resting state. GTP on the alpha subunit is hydrolyzed to GDP, and adenylyl cyclase is deactivated.
- largest receptor family
- response lasts minutes
13
Q
Enzyme-linked Receptors
A
• When activated, phosphorylate tyrosine residues on themselves and then other specific proteins • Acts as a molecular switch • Multiplication of initial signal • Response lasts minutes to hours -activates enzymes inside of the cell
14
Q
Intracellular Receptors
A
• Ligand must diffuse into the cell to interact with receptor
• Primary target: transcription factors in cell nucleus
• Response lasts hours to days
-takes a little for a response and once the proteins are formed then the response lasts hours to days
-not easily reversible
15
Q
Two Important Features of Signal Transduction
A
- The ability to amplify signals
2. Mechanisms to protect the cell from excessive stimulation
