Lec #1 The Human Brain Flashcards
Dopaminergic neuron
neuron that releases dopamine
Glutamatergic neuron
neuron that releases glutamate
Excitatory neurotransmitter
released neurotransmitter when bonded to a downstream neuron, causes the neuron to fire more and depolarize the membrane
Inhibitory neurotransmitter
released neurotransmitter when bonded to a downstream neuron, causes the neuron to fire less and hyperpolarize the membrane
membrane potential
- the difference in electrical charge or voltage between the inside and outside of a neuron
- typically negative inside the cell relative to the outside. This difference in charge results from the selective permeability of the cell membrane to ions (charged particles): sodium, calcium and potassium and chloride (positive)
what happens when if a membrane is depolarized enough?
a strong electrical current goes down the axon, the action potential with sufficient amount of positive ions flowing in and triggers calcium channels to enter the axon terminal and causes the release of neurotransmitters
action potential
the electrical current that flows through the axon. When it reaches the end of the axon (terminal), the electrical cuttrny triggers the release of neurotransmitter
drug
A chemical that interacts with a protein to alter its activity.
endogenous ligand (endogenous agonist)
naturally occurring substance within the body that can bind to and activate specific receptors in the body, such as cell surface receptors or intracellular receptor
receptor
The protein that is altered by the drug through a physical interaction between the drug and the protein.
therapeutic target
The target (receptor) that is believed to be the reason why the drug is
effective to treat a disease condition.
therapeutic effect
The beneficial change in physiology that occurs with drug administration.
For example, analgesia (pain-relief) is the therapeutic effect of morphine.
off-set target
The interaction of the drug with other proteins that are not part of the therapeutic effect. Off-target actions of the drug can contribute to unwanted adverse effects(also called side effects). If a drug has off-target effects that are the reason for the adverse effects, it suggests that a more selective drug could provide the same benefits with fewer side effects.
adverse effect
An undesirable and/or pathogenic change in physiology that occurs with drug administration.
mechanism of action
A drug’s mechanism of action is our current understanding of that drug’s target(s), and how the interaction of drug and receptor leads to a change in neuron activity that ultimately changes brain function.
affinity
the strength of the attraction between the drug and the receptor. A drug with high affinity will have several points of electrostatic interactions. For example,
several negatively charged ions on the drug will come in contact with positively charged amino acids on the receptor. A drug with high affinity is often very selective for its target, because each protein has a unique shape.
selectivity
the number of proteins that are affected by a drug. A highly
selective drug will only bind one or two proteins, while a non-selective drug will bind several.
what are 3 steps of finding drugs to treat brain diseases?
- take a natural product and isolate the psychoactive chemical
- identify the receptor for that chemical
- change the chemical structure to improve the drug and how well it fits/ acts on the receptor
Acronym for ADME
Absorption
Distribution
Metabolism
Elimination
agonist drug
a substance that binds to a receptor and activates it, often mimicking the effects of endogenous (naturally occurring) compounds or neurotransmitters.
antagonist drug
substance that binds to a receptor without activating it and blocks or inhibits the receptor’s normal activity.
Antagonists compete with agonists (including endogenous ligands) for receptor binding sites, preventing the receptor from being activated.
Antagonist drugs are used to reduce or block the effects of agonists, typically for therapeutic purposes or to study the specific functions of receptors.
what happens when a neurotransmitter binds itself to ion channels:
2 reactions:
- If the neurotransmitter binding to its receptor on the ion channel leads to the opening of ion channels that allow positively charged ions (typically sodium, Na+) to flow into the neuron, this results in an excitatory postsynaptic potential (EPSP).
- when a neurotransmitter binding to its receptor opens ion channels that allow negatively charged ions (typically chloride, Cl- or potassium, K+) to flow into the neuron or positively charged ions (such as potassium, K+) to flow out of the neuron, this results in an inhibitory postsynaptic potential (IPSP).
what does it mean when the drug is transient (reversible)
the drug does not go on the receptor forever, can go into the bloodstream and be eliminated
what happens when the receptor for a drug is activated so much by an agonist?
desensitization= receptor activated so much, that it refuses to send the signal anymore
what is the only way to stop the action of a drug that binds irreversibly to a receptor?
make a new receptor (takes several hours)
What happens when a drug is present continuously in a cell?
The cell will adapt to the presence of the drug.
What occurs with receptors when a drug acts as an antagonist?
Receptors are sometimes upregulated, leading to the production of more receptor proteins.
What happens to receptors when a drug functions as an agonist?
Receptors are sometimes downregulated, resulting in a decrease in the number of receptor proteins.
what part of the neuron determines whether a neuron will fire
axon hillock
