Drug & Receptor Interactions Flashcards
What is a receptor?
A protein that responds to a stimulus and transmits chemical signals to produce a response
What is a ligand?
An ion/molecule that forms a complex with a another molecule
What is a prodrug?
A compound that must undergo chemical conversion by metabolic processes before becoming an active pharmacological agent.
Give an example of a prodrug and how it works
Diamorphine - when it enters the brain it is converted into morphine which binds to mu opioid receptors
Define bioavailability
Extent and rate at which the active drug enters systemic circulation
Define affinity
How tightly a drug binds to its receptor
Define efficacy
The capacity of a drug to produce a change in a target cell/organ after binding to a receptor
Define potency
A measure of the amount of drug required to produce an effect of given intensity
What is an agonist?
A neurotransmitter/drug that mimics the action of a neurotransmitter and binds to its receptor
Agonists have a _____ affinity for its own receptor and can produce an _______ or ______ effect of the post-synaptic neuron
high
excitation
inhibition
Partial agonists produce a higher/lower response than a partial/full agonist after binding
lower
full
What is an inverse agonist?
A ligand that binds to the same receptor binding site as an agonist
An agonist increases/decreases the activity of a receptor above its basal level.
An inverse agonist increases/decreases the activity of a receptor below its basal level.
increases
decreases
What can block the effects of agonists and inverse agonists?
antagonists
What is an antagonist?
A drug that has affinity for a neurotransmitter receptor and prevents the action of a neurotransmitter to bind to its own receptor
What is an inhibitor?
A molecule that binds to another e.g. enzyme and decreases its activity.
Give 2 ways in which some drugs inhibit activity of a neuron
- hyperpolarization of neuron
- blockade of binding of a neurotransmitter to its own receptor
Give an example of agonists that inhibit the postsynaptic neuron
GABA
Diazepam
Morphine
Give an example of an antagonist that inhibits the influx of Ca2+ ions
Nifedipine
Give an example of an antagonist that inhibits the B1-adrenergic receptor
atenolol - beta blocker
What causes disinhibition?
The inhibition of the inhibitor
Describe how the release of endorphin can cause the excitation of synaptic transmission through disinhibition of GABAergic inputs
- opioidergic neuron is depolarised
- endorphin is released which binds to opioid receptors on GABA
- The activation of the receptors causes hyperpolarisation of GABA
- GABA neuron stops exerting an inhibitiory control over dopamine
- The dopamine neuron can fire and release dopamine
What is the collective name of the 3 protective membranes that cover the skull?
meninges
What are the 3 layers of the meninges called?
- dura mater
- arachnoid layer
- pia mater
List the 3 main functions of the meninges
- protection
- blood supply
- gives space for the flow of cerebrospinal fluid
Describe how the blood brain barrier maintains a neutral environment
- regulates passage of molecules in/out
- protects brain from microorganisms and toxins circulating in the blood
What are the 2 main pairs of arteries that the brain relies on for its blood supply?
- internal carotid arteries
- vertebral arteries
What part of the brain do the internal carotid arteries supply blood to?
anterior brain
What part of the brain do the vertebral arteries supply blood to?
posterior brain
brainstem
What happens to the brain when it is without O2 and important nutrients?
- brain cells are damaged/ die within minutes
- damage leading to physical/cognitive/mental disabilities
What term refers to the blood flow in the brain?
Cerebrovascular
Define Cerebral blood flow (CBF)
the blood supply to the brain in a given time
What is an adults typical CBF?
750mL/min
or
15% of CO
What term describes too much blood flow?
hyperemia
What can hyperemia lead to?
intracranial pressure (ICP)
List the 3 purposes of the cerebrospinal fluid (CSF)
- buoyancy against gravity
- protection - from brain striking cranium when jolted
- chemical stability
The brain and CSF are similar in ________, which makes the brain float in neutral ________ suspended in CSF
density
buoyancy
What cells of the choroid plexus produce the CSF ?
ependymal cells
