Drugs And Receptors Flashcards
What is the lock and key mechanism?
Drug- key will on,y bind to a specific receptor- lock
Where are the targets for drug actions?
Receptors Ion channels Carrier/molecules pumps Enzymes DNA
What happens when a drug binds to a receptor?
Receptors are usually located in plasma membrane
Drug binds to receptor and signals change within the cell, alters cell properties
I.e. Change shape or secrete a chemical
Connected to second messenger such a G protein
What happens when drug binds to ion channels?
Acts directly on ion channels
Cause the channels to open or close
Changes the electrical activity of the cell, which may lead to excitation or inhibition
How is the carrier molecules/ pumps affected?
Carriers are proteins which allow substances to enter the cell
Drugs that interact with them either increase or decrease the uptake of the substance into the cell
What happens when drugs bind to enzymes?
Either inhibit or excite the activity of the enzyme
Reactions are either slowed down or sped up
What happens when drugs bind to DNA?
In the cell nucleus
Influence the way in which DNA message is transcribed or copied yo produce mRNA and proteins.
This can directly increase or decrease the synthesis of proteins
What are other drug targets?
Selective toxicity- some drugs target proteins that are not found in the human cells such as penicillin: cell wall
Anti fungals- target a form of cholesterol not found in human membrane
Antivirals- block enzymes involved in replication or prevent virus entry into the host cell
Antihelmintics-drugs which expel parasitic worms from the body by stunning or killing them
Amoebicides- interfere with DNA of amoeba preventing them from reproducing example: metronidazole
Give an example of s drug that binds to enzymes
Aspirin: blooms the cox 2, responsible for producing PG, which cause inflammation.
Viagra :blocks the enzymes responsible for relaxing smooth muscles in blood vessels, blood vessels dialyse casing more blood flow.
Give an example of drug that binds to receptors
Salabutomol: b agonist, chemical structure similar to that of the hormone adrenaline. Causes airways to widen
Beta-blockers:stop adrenaline binding to receptors, high blood pressure or arrhythmias
Anti-histamine: blocks I stamina receptors in airways, nasal cavity, eyes, skin
Give an example of drug that binds to ion channels
Local anaesthesia: block sodium channels, stop nerve impulse
Valium
Benzodiapines: anti anxiety, acts on GABA, slows down transmission to brain.
Give an example of s drug that binds to pumps
Omaprazole: PPI, reduce acid secretion in stomach, trade gastric and duodenum ulcers, heart burn.
Cocaine: reduces the uptake of chemical transmitter noradrenaline, causing it to remain in the synapse. Stimulators effect.
Give an example of s drug that binds to DNA
Hydrocortisone- steroids, reduces production of proteins that cause inflammation, suppress immune response
Give an example of s drug that binds to foreign proteins
Penicillin: antibiotics. Weakens the cell wall of certain bacteria,stop them growing and dies
Ketocoanazole: anti fungal. Blocks production of ergosterol which forms the part of the fungal cell membrane, resulting in holes, cell content leaking out
Name the two types of cell interaction
Agonist and antagonist
What does agonists do?
Bind to receptor causing a response and often mimic the chemicals in the body
Example: b-agonist , Salabutomol: binds to receptor forms a complex, once complex formed its activated to cause a response
Insulin- insulin receptors
Nicotine- nicotine receptors
What does the antagonist do?
Binds to receptor and stop chemicals from producing a response
May be reversible or irreversible
They compete with agonist for space, they occupy the space where the agnostic normally fits in. Thus when antagonist bind to the receptor the agonist can’t produce a full response
If the antagonist concentration is high enough, the agonist will be abolished.
Example: propranolol, competes with adrenaline to slow heart down
Antropine, compete with AcH to block AcH receptors
What happens when a drug binds to a receptor?
Activates the second messengers, cascade of enzyme reactions and finally a response
Give an example of a drug binding to a receptor and how a response occurs
Agonist I.e. Salabutomol, binds to b receptor causing the activation of G protein. This stimulus the second messenger adenylate cyclase enzyme to convert ATP to cAMP. cAMP converts inactive protein 1 to active protein 1. Causing protein 2 to lose calcium from the cytoplasm, causing a response of relaxation.
What happens when a steroid binds to a nuclear receptor?
Steroids must enter the cell before causing a response.
They are lipid soluble and so can cross the cell membrane
Once in the sytoplasm, the steroids bind to free receptors to for a complex
2 complexes join together allowing them to enter the nucleus
Once inside, binds to DNA, genes are either switched on or off, if switched on RNA is produced, rescue protein production
List the cellular response to drugs
Contraction Secretion Excitation Inhibition Interruption of cell cycle
What is potency?
How much of the drug is needed to produce a response
High potency: small dose needed
How do drugs work?
Bind to a particular part of a cell or tissue and produce a response
Normally proteins found in the cell
