Nervous System and Brain Pathways
Neurotransmission
Ion Channels
Pharmacokinetics and Bioavailability
Choosing the Right Drug
100
What is the primary function of the parasympathetic branch of the autonomic nervous system?
It regulates the body's rest and digest functions, slowing the heartbeat, stimulating digestion, and promoting relaxation.
100
What is the resting potential of a neuron, and what does it mean?
–70 millivolts (mV); it is the electrical charge of a neuron when it is not actively transmitting a signal.
100
What type of ion channel is quickly activated by neurotransmitter binding and allows ions to flow through the cell membrane?
Ionotropic (ligand-gated) ion channels.
100
What does bioavailability refer to in pharmacokinetics?
The amount of a drug that is available to the body after it has been metabolized.
100
What type of drug acts as a receptor antagonist by blocking neurotransmitter effects?
Antagonists.
200
What does the acronym S.L.U.D.D. stand for, and which branch of the autonomic nervous system does it represent?
Salivation, Lacrimation, Urination, Digestion, and Defecation; it represents the parasympathetic nervous system.
200
What happens to the charge of a neuron when it reaches the threshold of excitation?
The charge rapidly changes from –70 mV to +40 mV, creating an action potential.
200
Which ions are primarily associated with voltage-gated ion channels?
Sodium (Na+), Potassium (K+), Calcium (Ca2+), and Chloride (Cl–).
200
Which route of administration has the highest bioavailability and why?
Intravenous (IV) administration, because it delivers the drug directly into the bloodstream, bypassing absorption barriers.
200
Which drug administration route would be most appropriate for delivering a fast-acting bronchodilator for an asthma attack?
Inhalation
300
What is the primary difference between the somatic and autonomic nervous systems?
The somatic nervous system controls voluntary movements of skeletal muscles, while the autonomic nervous system regulates involuntary functions like heartbeat and digestion.
300
What ions are primarily located outside and inside the neuron during its resting potential?
Outside: Sodium (Na+) and Chloride (Cl–); Inside: Potassium (K+) and negative anions (A–).
300
What is the function of the G-protein in metabotropic ion channels?
The G-protein, once activated by a neurotransmitter, opens ion channels or activates intracellular signaling pathways, mediating diverse and prolonged cellular effects.
300
What is the "First Pass Effect," and how does it impact oral drug administration?
The process where the liver metabolizes a drug before it reaches systemic circulation, reducing the drug's potency by roughly 25%.
300
What is synergism, and how does it differ from potentiation?
Synergism multiplies the effect of a drug when combined with another drug with complementary properties, whereas potentiation enhances the effect of one drug without the second drug having an independent effect.
400
Which neurotransmitter is primarily associated with the mesolimbic pathway, and what symptoms might an increase in this pathway cause?
Dopamine; an increase can cause delusions, hallucinations, and other positive symptoms associated with conditions like schizophrenia.
400
What is happening to a neuron during #4?
The neuron is unable to fire another action potential as it returns to its resting state, ensuring signals move in one direction.
400
What is the key difference between ionotropic and metabotropic ion channels?
Ionotropic channels open directly when a neurotransmitter binds, while metabotropic channels use G-proteins to open ion channels indirectly and have slower, longer-lasting effects.
400
How does depot binding influence the duration of a drug's effect?
Depot binding occurs when a drug binds to inactive sites like fat or muscle tissue, slowly releasing into circulation over time, extending the drug's therapeutic effects.
400
What type of medication would be used to treat symptoms associated with dopamine deficiency in Parkinson’s disease?
Dopamine agonists
500
Which midbrain structure is a major producer of dopamine, and what is its role in the mesolimbic and mesocortical pathways?
The ventral tegmental area (VTA); it sends dopamine to the limbic system (mesolimbic pathway) and the cerebral cortex (mesocortical pathway), influencing mood, motivation, and cognitive functions.
500
How do the nodes of Ranvier enhance the speed of electrical signal transmission in myelinated axons?
The electrical signal "jumps" from one node to the next in a process called saltatory conduction, bypassing insulated sections and significantly increasing transmission speed.
500
What is the primary function of chloride (Cl–) channels in inhibitory neurotransmission?
Chloride channels allow Cl– to enter the neuron, hyperpolarizing the membrane and making it less likely to fire an action potential.
500
What is the therapeutic index, and why is it important in drug dosing?
The therapeutic index is the ratio of a drug's toxic dose (TD50) to its effective dose (ED50). A higher therapeutic index indicates a safer drug.
500
What is the primary risk of synergism when combining CNS depressants like alcohol and opioids?
Increased risk of respiratory depression and overdose.