Pharmacology Flashcards
(33 cards)
Define Pharmacology?
The component of medicine that explains the use, mechanisms and effects of drugs
Define ‘drug’?
A drug is a chemical substance of know structure (other than a nutrient or dietary factor) which, when administered produces a measurable biological effect
What are drugs called that work by blocking a receptor on or within a cell called?
Antagonists
What is Pharmodynamics?
This refers to how the drug works and how effective it is on body function
What is pharmacokinetics?
This is what the body does to medication and how it does it. It refers to each of the separate components including Absorption, Distribution, Metabolism and Excretion
What is meant by bioavailiability?
The percentage of active drug that is administered into a patient that actually makes it into circulation.
What are the 2 main ways for excretion of a drug?
Renal excretion- through urine
Hepatobiliary excretion- Lost in faeces
What is meant by a single blinded trial?
The volunteers do not know whether they are given the drug or placebo to avoid bias.
What is meant by a teratogen?
A substance that can cause abnormalities or birth defects in a developing foetus if the mother takes it.
What is an enzyme?
Proteins.
Biocatalysts.
Often modified with lipid, carbohydrates vitamins and metal ions.
How do enzymes contribute to metabolism?
Enable control of biochemical reactions.
Enable control of biochemical pathways- One enzyme can act as the rate limiting enzyme which can therefore control the rate of the whole pathway,
How do enzymes work?
They lower the activation energy between substrate and product.
Induced fit model. Active site on enzyme changes shape slightly to fit around substrate.
How do hydrophobic signalling molecules work?
They repel water so move around the extracellular space bound to a carrier protein. They then get delivered to the target cell where they are then offloaded and can diffuse freely across the cell surface membrane.
How do hydrophilic signalling molecules work?
They stay in water but can’t cross the cell membrane so instead bind to transmembrane protein receptors in the cell surface membrane to trigger a response. This is the more common type.
What are the 3 stages of cell signalling?
Reception- Receptors bind to ligand
Transduction- Receptor protein changes and activates intracellular molecules (2nd messengers)
Cell Response- The response to the signal.
How do G protein coupled receptors work?
They are on the cell surface membrane and cross over the membrane 7 times before ending inside the cell. On this end they are attached to a G protein (made up of 3 subunits- alpha, beta and gamma).
Alpha and gamma subunits are anchored to the cell membrane and keep the G protein right next to the receptor.
What do G proteins bind to when they are inactive?
GDP. This is attached to the alpha subunit and cause the 3 subunits to stay together so that the flower is closed.
What happens when a ligand binds to a G protein coupled receptor?
This causes a change in shape of the G protein coupled receptor and this allows the G protein to dissociate with GDP and instead bind to GTP which activates the G-protein. This causes the alpha subunit to separate from the others which opens up the G protein so the alpha subunit is free to interact with other molecules.
What are the 3 types of G protein? Which ones are stimulatory and which are inhibitory?
Gq- DAG
Gs- adenylate cyclase enzyme- cAMP
Gi- adenylate cyclase (inhibits it- negative feedback on Gs so it inactivates cells)
Gq and Gs are stimulatory and Gi is inhibitory
What is an enzyme coupled receptor?
This is where a transmembrane protein has a receptor on the extracellular side and a enzyme on the intracellular side.
How do tyrosine kinase receptors work?
Type of enzyme coupled receptor:
2 ligands bind which draws 2 tyrosine chains together forms a dimer.
They then cross phosphorylate each other.
This triggers the signalling pathway.
How are tyrosine kinase associated receptors different to tyrosine kinase receptors?
No intrinsic enzyme activity.
Associated with cytoplasmic tyrosine kinase which phosphorylates target proteins to relay signal.
How do ion channel receptors work?
They open up once they bind to a specific ligand.
This is how ions such as Na+ and K+ move across the membrane.
A ligand binds to the channel receptor which opens the channel so the ions flow down the concentration gradient.
This results in a shift in electric charge distribution inside the cell causing a cellular response.
What is the effect of Km on enzyme affinity?
If Km is high then the enzyme will have lower affinity for its substrate as lots of substrate is required to achieve a fast rate.
If Km is low then the enzyme will have a high affinity.
