Neurophysiology: Action Potential and Repolarization

The state of a neuron where it is more negative than its resting potential. This occurs after an action potential due to the continued outflow of potassium ions, making the cell more negative than usual.

A protein embedded in the cell membrane that pumps sodium ions out of the cell and potassium ions into the cell. It helps restore the resting membrane potential after an action potential.

A type of ion channel that allows potassium ions to move across the cell membrane. It plays a role in repolarizing the neuron after an action potential.

A type of ion channel that allows sodium ions to move across the cell membrane. It plays a role in depolarizing the neuron during an action potential.

The state of a neuron where it is inactive and not able to fire an action potential. This occurs after the channel has been activated and inactivated.

The state of a neuron where it is ready to fire an action potential. This occurs when the channel is closed but can be opened by a stimulus.

The difference in electrical charge between the inside and outside of a neuron at rest. It is typically around -70 millivolts.

The process of returning a neuron to its resting membrane potential after an action potential. It involves the movement of potassium ions out of the cell and the inactivation of sodium channels.

Hypocalcemia impairs the closing of sodium channels, causing prolonged depolarization and repetitive firing.

Hypercalcemia decreases cell membrane permeability to sodium, hindering neuron excitation.

Hypokalemia leads to a more negative resting membrane potential due to potassium loss.

Sodium channel blockade prevents reaching threshold potential, halting action potential generation.

The synapse is the junction between two neurons, where communication occurs through neurotransmitters.

Vesicles containing neurotransmitters are released into the synaptic cleft by calcium-mediated fusion with the presynaptic membrane.

Reuptake pumps on the presynaptic membrane recycle neurotransmitters back into the presynaptic neuron.

Synaptic modulation refers to changes in synaptic function, affecting communication between neurons.

A slight delay in transmission occurs at the synapse due to the time required for neurotransmitter release, diffusion, and binding.

Repetitive stimulation can lead to synaptic fatigue, reducing the postsynaptic cell's response.

Downregulation of receptors reduces the sensitivity of the postsynaptic cell to neurotransmitters.

An action potential is a rapid electrical impulse that travels along a neuron, facilitating communication.

Efferent action potentials are sent away from the cell body, transmitting information to other neurons or tissues.

Afferent action potentials are received by the cell body, bringing information from other neurons.

Postsynaptic density is a specialized region on the postsynaptic membrane containing receptors and other molecules involved in synaptic transmission.

A state where a neuron is unable to produce a response, often caused by depletion of neurotransmitters or constant stimulation.

A neurotransmitter depletion that can occur in heart failure patients due to constant stimulation of the sympathetic nervous system.

A technique used to assess neuromuscular blockade by stimulating the nerve repeatedly.

The ability of a neuron to respond to stimulation, influenced by factors like neurotransmitter levels, pH changes, and oxygen availability.

Molecules that bind to receptors, triggering a cellular response.

The minimum concentration of a ligand required to elicit a cellular response.

The ability of a ligand to bind to a specific type of receptor.

The specific cellular response elicited by the activation of a receptor, which varies depending on the tissue.

The strength of the bond between a ligand and a receptor, which can range from weak to strong.

The polar heads of phospholipids are hydrophilic and face the exterior of the cell membrane.

The nonpolar tails of phospholipids are hydrophobic and cluster together inside the cell membrane.

A membrane-bound structure that allows the passage of specific molecules across the cell membrane.

The ability of a molecule to dissolve in lipids, making it easier to pass through the cell membrane.

The movement of molecules from an area of high concentration to an area of low concentration.

A change in the shape of a receptor protein caused by the binding of a ligand.

A type of receptor that allows ions to pass through the cell membrane when a ligand binds.

The state of a receptor when it is not bound to a ligand.

The state of a receptor when it is bound to a ligand and allows ions to pass through.

A type of receptor that is coupled to a G protein, which is activated when a ligand binds.

A type of receptor that is linked to an enzyme, which is activated when a ligand binds.

A type of receptor that is located in the nucleus of cells and binds to hormones and other molecules that affect gene expression.

An ion that flows into the cell, causing a change in membrane potential.

An ion that flows out of the cell, causing a change in membrane potential.

A neurotransmitter that binds to receptors in the central nervous system and is involved in learning and memory.

A neurotransmitter that binds to receptors in the central nervous system and is involved in inhibiting neural activity.

A neurotransmitter that binds to receptors in the spinal cord and is involved in inhibiting neural activity.

The process by which a drug molecule binds to a receptor, leading to a change in the receptor's shape and an effect on the cell.

A nonpolar molecule that can interact with other nonpolar molecules, such as cell receptors. It's important for drugs to be lipophilic to bind effectively to receptors.

A type of intermolecular bond involving a hydrogen atom and a highly electronegative atom, like oxygen or nitrogen. Common in drug-receptor interactions and helps hold enzymes together.

Alternative binding sites for drugs on proteins like albumin. These sites can 'trap' a drug, preventing it from reaching its intended target receptor.

Endogenous proteins that are alternative drug binding sites. They often bind non-specifically and don't have a specific intended effect.

A type of receptor that forms a complex with a G protein, triggering a cascade of intracellular events. It's important for many drug actions.

A type of receptor that opens in response to changes in the cell's electrical potential. This allows ions to flow through and influence cell activity.

The weakest type of intermolecular attraction, involving temporary fluctuations in electron distribution. It's common in drug interactions, but weaker than other bonds.

A strong, permanent link between two atoms, often involving the sharing of electrons. Uncommon in drug interactions, but can be important in some cases.

A drug that binds permanently to its receptor, usually through a covalent bond. It can have long-lasting effects.

The duration of time that a drug remains effective in the body. This can vary depending on the drug's interactions and binding.

A type of interaction between two molecules with opposite charges. These forces can be weaker than hydrogen bonds, but still important for drug interactions.

A molecule that dislikes water and prefers to interact with other nonpolar molecules. This is important for drugs to cross cell membranes.

A drug that binds to a receptor and produces a desired effect for an extended duration.

A drug that blocks the effects of a specific receptor by binding to it.

An undesirable effect of a drug that lasts for a significant period.

A type of drug interaction where the drug binds permanently to its target receptor.

The study of the three-dimensional arrangements of atoms and molecules.

A molecule with a non-superimposable mirror image.

Two mirror image molecules that cannot be superimposed.

A mixture containing equal amounts of two enantiomers.

The isomer of a chiral molecule that rotates plane-polarized light to the left.

The isomer of a chiral molecule that rotates plane-polarized light to the right.

A racemic mixture of the S and R enantiomers of ketamine.

An isolated, pure form of S-ketamine, which is the preferred enantiomer.

Local anesthetic that can be cardiotoxic if injected into a blood vessel.

Local anesthetic that is less cardiotoxic compared to arbupivacaine.

A process where a cell increases the number and sensitivity of its receptors to respond to a stimulus, typically due to decreased or absent activity.

A process where a cell decreases the number and sensitivity of its receptors to reduce its response to a stimulus, typically due to excessive stimulation.

A drug that binds to a receptor and activates it, mimicking the effect of the natural ligand.

A drug that binds to a receptor and blocks the effect of the natural ligand, preventing activation.

A type of drug study conducted on healthy individuals to evaluate the drug's effects and safety.

Adjusting the dosage of a medication based on the individual patient's response, rather than solely relying on standard guidelines.

A graph that illustrates the relationship between drug dosage and the magnitude of its effect.

The point on a dose-response curve where further increasing the dose does not result in a greater response.

The study of the interactions of drugs with living organisms.

The practice of tailoring medication therapy to an individual patient based on their unique characteristics and needs.

The branch of pharmacology that deals with the use and effects of drugs in treating diseases.

A drug that increases the effect of GABA, an inhibitory neurotransmitter, leading to sedation and other effects.

The science that deals with the study of drugs and their effects on the body.

The study of drug movement throughout the body, including absorption, distribution, metabolism, and excretion.

The study of the mechanisms of action of drugs and their effects on the body.

The steepness of the dose-response curve, reflecting the number of receptors that need to be bound for a drug to have an effect.

The ability of a drug to produce a maximal clinical effect.

The concentration of a drug required to produce a specific response.

The concentration of a drug that produces 50% of its maximal effect.

The dose of a drug that produces a desired response in 50% of the population.

The ratio of the lethal dose (LD50) to the effective dose (ED50), indicating the safety margin of a drug.

An agonist that binds to a receptor and produces a full response.

An agonist that binds to a receptor and produces a partial response.

A drug that binds to a receptor and reduces activity below the baseline.

A drug that produces a spectrum of effects depending on the concentration of the drug.

The effect of a drug can vary between individuals depending on things like...

The dose-response curve is a tool used to characterize the relationship between...

A type of antagonist that competes with the natural ligand for the same binding site on the receptor.

The tendency of a cell or tissue to increase the number of receptors for a specific ligand in response to prolonged exposure to a low concentration of that ligand.

A type of drug that binds to a receptor at a site different from the main ligand-binding site, altering the receptor's function by either enhancing or reducing the effect of the natural ligand.

An example of a non-competitive antagonist used to reverse the effects of rocuronium, a muscle relaxant.

An example of a competitive antagonist used to reverse the effects of opioids.

The process of a cell increasing the number of receptors for a specific ligand in response to prolonged exposure to a low concentration of that ligand.

A type of drug that binds to a receptor at a site different from the main ligand-binding site, altering the receptor's function by either enhancing or reducing the effect of the natural ligand.

An example of a non-competitive antagonist used to reverse the effects of rocuronium, a muscle relaxant.

An example of a competitive antagonist used to reverse the effects of opioids.

A partial agonist can occupy receptors and block the effects of a full agonist. This can be problematic, especially in patients who are opioid-dependent.

A full agonist's typical dose-response curve changes when an antagonist is introduced. The curve shifts to the right (loss of potency) and may also flatten (loss of efficacy) depending on the type of antagonism.

A drug that causes a temporary state of unconsciousness and pain relief. Examples include Propofol and Fentanyl.

A beta blocker that slows down the heart rate and reduces blood pressure. It acts as an antagonist to norepinephrine.

A neurotransmitter that stimulates the sympathetic nervous system, increasing heart rate and blood pressure.

A type of muscle relaxant commonly used for intubation and surgery. It is a full agonist that causes a temporary paralysis of muscles.

A drug's effect is increased by another drug that acts on the same receptor, but in a different way, like a benzodiazepine enhancing GABA's effect.

A drug's effect is reduced by another drug acting on the same receptor. The opposite of PAM.

The combined effect of two drugs is equal to the sum of their individual effects. Like adding two doses of anesthesia together.

One drug prevents or blocks the effect of another drug.

The combined effect of two drugs is greater than the sum of their individual effects. This can be dangerous with anesthetics and opioids.

One drug enhances the effect of another drug, similar to a synergistic effect, but may also lead to dangerous interactions.

A decrease in a drug's effectiveness after repeated administration. It's not fully understood, but might be due to pharmacokinetic or pharmacodynamic changes.

The body's ability to produce less of a response to a drug over time, often with high doses of vasoconstrictors like phenylephrine.

A combination of drugs that each work on different pathways to achieve a greater effect. Used for HIV/AIDS treatment.

An example of potentiation in action, where a drug given before a diuretic potentiates its effect.

Giving drugs together can have unexpected effects, especially when they work synergistically. This can lead to unintended consequences, such as respiratory depression.

A decrease in a drug's effect over time due to the body's adaptation to the drug, often requiring increased doses to achieve the same effect.

A drug that increases the effectiveness of furosemide, a diuretic, which helps in treating fluid retention.

The concentration of a drug needed to produce half of its maximal effect.

A drug that binds to a receptor and produces a response (effect).

The ability of a drug to elicit a response at a given concentration.

The maximum effect a drug can produce, regardless of the dose.

The ratio of the lethal dose (LD50) to the effective dose (ED50). It indicates the safety margin of a drug.

A drug that binds to a receptor but does not activate it, preventing the agonist from binding.

A decrease in the response to a drug over time with repeated administration.

The study of how genetic variations influence an individual's response to drugs.

Differences in drug metabolism among different populations.

Differences in drug effects at the receptor or tissue level between individuals.

The use of genetic information to personalize drug selection and dosage.

A competitive antagonist shifts the dose-response curve to the right.

A non-competitive antagonist shifts the dose-response curve down and to the right.

The slope of a dose-response curve reflects the number of receptors occupied by the drug.

The higher the pH, the more ionized the acid will be in the plasma, resulting in a higher concentration of its conjugate base (A-) floating around on the plasma side compared to the other side of the membrane.

The blood-brain barrier is a semi-permeable membrane that regulates the passage of substances from the blood to the brain. It plays a crucial role in protecting the brain from harmful substances.

Drug molecules can bind to different proteins in the body, including albumin, which can sequester the drug and prevent it from reaching its target receptor. This can affect the drug's efficacy.

Variations in DNA sequence that can lead to differences in how people respond to drugs. For example, a change in a single nucleotide can affect how well a person metabolizes a drug.

A single nucleotide polymorphism (SNP) is a variation in a single nucleotide base in a DNA sequence. It's one of the most common types of genetic variation.

The CYP450 enzyme system plays a crucial role in breaking down drugs. Cyp2D6 is a particular enzyme involved in metabolizing many drugs including opioids.

People who are poor metabolizers of a drug might experience more prolonged effects because their bodies don't break it down as efficiently.

A person who breaks down a drug quickly.

If you see a patient who seems to need a particular drug more often, consider the possibility of genetic variations affecting their metabolism.

Differences in how drugs are absorbed, distributed, metabolized, and excreted in different populations.

Factors like age, sex, weigh, body surface area, and genetic variations can all impact how a person responds to medication.

Sometimes patients may not respond to a drug as expected, or they might have an exaggerated response. This could be due to genetic variations or other factors.

Adjusting drug dosage based on a patient's individual characteristics, including genetics and demographics, to optimize treatment effectiveness.

Treatment algorithms based on genetic factors are increasingly used for conditions like heart disease, mental health, and more.

Females tend to be more sensitive to muscle relaxants and might emerge from anesthesia quicker than males.

Red-haired individuals often require higher doses of anesthesia.

Women in labor have a higher risk of awareness under general anesthesia due to progesterone's sedative effects, requiring less general anesthetic to achieve sedation, increasing the risk of remembering events during the procedure.

Progesterone's sedative effects contribute to increased sensitivity to general anesthetics during labor, meaning lower doses are needed to achieve the desired effect. This is unrelated to neuraxial anesthesia, which involves spinal or epidural injections.

Immature kidneys in newborns have reduced renal extraction of uncharged drugs. This means they may eliminate these drugs more slowly compared to adults, potentially leading to drug accumulation and longer-lasting effects.