process of how drugs work
- drugs bind to receptors and change their activity
- drugs that affect the brain bind to receptors in the brain
- change in receptor activity = change in neuron activity = change in brain funciton
what is a receptor
all cells have sensors (receptors), for a specific thing (ligand, lipids, or neurotransmitter)
a drug is (in terms of charge)
a 3D object with a positive and negative charge, it will fit into its receptor because it has the right 3D shape and its charges align with those of the receptor
three step process for finding drugs to treat brain diseases
- start with a natural product and isolate the psychoactive chemical
- find the receptors for that chemical
- change the chemical structure to make an even better drug (adding an atom here or there will change the shape, and it could change how well it fits and how it changes the receptors function)
modern methods for drug discovery (three steps)
- start with a drug target, like a neurotransmitter receptor or an enzyme
- test thousands of compounds to find the one that binds to your target and changes its activity
- probably change the chemical structure to make an even better drug
when a neuron becomes more excitable
excitatory neurotransmitter
when a neuron becomes less excitable
inhibitory neuron
where are receptors located
surface of the cell
receptors signal to the cell by
changing shape when they bind to their ligand or drug
when the neurotransmitter or drug binds to the ion channel
it opens up a pore to allow ions to flow in or out of the cell
drug binding to a receptor is usually
transient (reversible)
once a drug becomes unbound from a receptor
it can bind to another receptor or it can be eliminated from the body
some drugs bind
irreversibly and the only way to stop their action is to make a new receptor (usually takes several hours)
if a drug is present continuously
the cell will adapt to the presence of the drug, receptors are sometimes upregulated when the drug is an antagonist. receptors are sometimes downgraded when the drug is an agonist
- this is the reason for tolerance and physical dependence
what does upregulate mean
receptors make more protein
tolerance definition
needing more of the same drug to get the same effect
what is the brain
the organ that senses important aspects of the environment and the boy and coordinates the appropriate response
basic functional unit of the brain is the
neuron
sodium / calcium channels
positive charge and are excitatory
chloride channels
negative charge and are inhibitory
When the neurotransmitter or drug binds the channel, it opens up a pore to allow ions to flow in or out of the cell it is called a
ligand gated channel
voltage gated means that
they open a channel in response to an electric current
voltage gated sodium channels help to transmit
the excitatory signal - makes a local excitation travel down the neuron to axon hillock and the axon terminal
voltage gated calcium channels are important
at the axon terminal when the action potential reaches the end, it opens up the voltage gated calcium channela
