NUR 521 Exam 1 Study Guide Part 2
Module 2: Chapters 11-25
Foundations of Neuropharmacology:
The study of drugs that alter processes controlled by the nervous system.
These drugs produce the same effect of natural activity in the body.
2 main categories:
o Peripheral Nervous System (PNS) drugs.
o Central Nervous System (CNS) drugs.
**The nervous system regulates all bodily processes. Must 1st understand how neurons regulate
bodily function when drugs are absent.
Neurotransmitters- chemicals that transmit signals specifically between nerve cells (neurons) in
the nervous system, allowing communication within the brain and between nerve cells and
muscles.
Hormones- chemical messengers produced by glands in the endocrine system, released into the
bloodstream and travel throughout the body to regulate various physiological processes, such
as growth, metabolism, and reproduction.
Neural regulation of other cells:
Two basic steps in the process by which the neuron influences the behavior of the postsynaptic
cell.
1. Axonal conduction: conducting of action potential down the axon of the neuron.
2. Synaptic transmission: information is carried across the gap between the neuron and
the postsynaptic cell. Requires the release of neurotransmitter (T) molecules from the
axon terminal followed by binding of these molecules to receptors on the postsynaptic
cell. (could be another neuron, a muscle cell, or a cell within a secretory gland) **These
drugs are much more selective**
This causes a change in behavior; the change depends on the neurotransmitter involved
and the type of cell involved.
i. Another neuron- may increase/decrease firing rate.
ii. Muscle cell- may cause contraction/relaxation.
iii. Glandular cell- may increase or decrease secretion.
Drugs can work to alter these 2 mechanisms. Most neuropharmacological drugs work
to alter synaptic transmissions. Only a few alter axonal conduction.
,Axonal Conduction: Not very selective because conducting an implulse along an axon is the
same in all neurons. Therefore, a drug that alters axonal conduction will affect conduction in all
nerves to which it has access. Cannot produce selective effects.
Example: local anesthetics- work by decreasing axonal conduction and suppress
transmission to any nerve they reach.
Synaptic Transmission: drugs that alter synaptic transmission, produce effects that are highly
selective. Selectivity can occur because synapses, unlike axons differ from one another and
synapses at different sites within the body use different neurotransmitters (hormones). For
most neurotransmitters the body has more than one type of receptor. These drugs have many
uses because of their selectivity.
Step 1: Transmitter synthesis- precursor molecules, which create transmitters must 1 st be
present in the presynaptic nerve terminal.
Step 2: Transmitter storage- after synthesized must be stored until time of release.
Occurs within vesicles (tiny packets) in the axon terminal. Each nerve terminal contains
a large number of transmitter-filled vesicles.
Step 3: Transmitter release- triggered by the arrival of an action potential at the axon
terminal. The action potential starts a process in which vesicles merge with the terminal
membrane. This lets their contents (transmitters) escape into the synaptic gap.
Step 4: Receptor binding- initiates a cascade of events that result in altered behavior of
the postsynaptic cell.
Step 5: Termination of transmission- removal of the transmitter from receptors, then
removal of free transmitter from the synaptic gap. Transmitters are removed from the synaptic
gap by either reuptake (taken back by the cell), enzymatic degradation (broken down by
enzymes), or diffusion (moved around).
The effect of a drug on a neuronally regulated process is dependent on how well it can
directly or indirectly change the activity of the receptors on target cells.
,Receptor activation:
Drugs that MIMIC the effects of natural neurotransmitters INCREASE receptor activation.
Drugs whose effects REDUCE the amount of natural transmitter available for receptor binding
DECREASE receptor activation.
Effects of drugs on the steps of Synaptic Transmission:
1. Transmitter Synthesis: can increase, decrease or cause synthesis of transmitter molecules
that are more effective than the natural transmitter itself.
2. Transmitter Storage: drugs that interfere with storage cause receptor activation to
decrease, disruption of storage depletes vesicles of their transmitters, decreasing the
amount of transmitter available for release.
3. Transmitter Release: drugs can promote or inhibit transmitter release.
a. Drugs that promote release, increase receptor activation.
b. Drugs that inhibit release, reduce receptor activation.
i. Amphetamines- promote transmitter release.
ii. Botulinum Toxin (Botox)- inhibit transmitter release.
4. Receptor Binding: many drugs act directly at receptors by:
a. Binding to receptors and cause activation.
i. Morphine, epinephrine, insulin.
b. Bind to receptors and block/prevent receptor activation by other agents.
i. Naloxone, antihistamines, metoprolol.
c. Bind to receptor components and enhance activation by the natural transmitter at
the site.
i. Benzodiazepines such as diazepam are used to treat anxiety, seizure
disorders, and muscle spasms.
5. Termination of Transmitter Action: drugs can interfere with the termination of a
transmitter action by two mechanisms.
a. Blockade of transmitter reuptake
b. Inhibition of transmitter degradation (the breaking down of transmitter by enzymes).
** Drugs that act by either above mechanism will increase transmitter availability, causing
receptor activation to increase**
Peripheral Nervous System Regulation:
Need to know 3 things to understand PNS drugs:
1. Type or types of receptors through which the drug acts.
2. The normal response to activation of those receptors.
3. What the drug does to the receptor function. Does in increase or decrease receptor
activation?
, Example:
• Isoproterenol is a B1 and B2 Agonist
• Agonist = a substance that initiates a physiological response when combined with a
receptor. Antagonist = a substance that blocks a physiological response.
• It acts on 2 types of adrenergic receptors: B1 and B2.
• When activated, B1 receptors increased HR and Increased force of cardiac
contraction.
• When activated, B2 receptors bronchial dilation and elevation of blood glucose
levels.
• Isoproterenol causes activation of both B1 and B2 adrenergic receptors.
We can now predict the principal effects of this drug. By activating β1 and β2 receptors,
isoproterenol can elicit three major responses: (1) increased cardiac output (by increasing
heart rate and force of contraction), (2) dilation of the bronchi, and (3) elevation of blood
glucose.
Take Home Point: For each PNS drug, you should learn (1) the identity of the receptors at
which that drug acts, (2) the normal responses to activation of those receptors, and (3)
whether the drug increases or decreases receptor activation.
By knowing which receptors drugs target, drug effects are relatively easy to predict.
The nervous system has two main divisions:
1. The central nervous system (CNS)
2. The peripheral nervous system (PNS)
Parasympathetic and Sympathetic Divisions of the PNS:
The PNS has two major subdivisions:
1. The Somatic Motor System: Controls voluntary movement of muscles.
2. The Autonomic Nervous System: further subdivided, both regulate many involuntary
processes.
a. Parasympathetic Nervous System
b. Sympathetic Nervous System
Module 2: Chapters 11-25
Foundations of Neuropharmacology:
The study of drugs that alter processes controlled by the nervous system.
These drugs produce the same effect of natural activity in the body.
2 main categories:
o Peripheral Nervous System (PNS) drugs.
o Central Nervous System (CNS) drugs.
**The nervous system regulates all bodily processes. Must 1st understand how neurons regulate
bodily function when drugs are absent.
Neurotransmitters- chemicals that transmit signals specifically between nerve cells (neurons) in
the nervous system, allowing communication within the brain and between nerve cells and
muscles.
Hormones- chemical messengers produced by glands in the endocrine system, released into the
bloodstream and travel throughout the body to regulate various physiological processes, such
as growth, metabolism, and reproduction.
Neural regulation of other cells:
Two basic steps in the process by which the neuron influences the behavior of the postsynaptic
cell.
1. Axonal conduction: conducting of action potential down the axon of the neuron.
2. Synaptic transmission: information is carried across the gap between the neuron and
the postsynaptic cell. Requires the release of neurotransmitter (T) molecules from the
axon terminal followed by binding of these molecules to receptors on the postsynaptic
cell. (could be another neuron, a muscle cell, or a cell within a secretory gland) **These
drugs are much more selective**
This causes a change in behavior; the change depends on the neurotransmitter involved
and the type of cell involved.
i. Another neuron- may increase/decrease firing rate.
ii. Muscle cell- may cause contraction/relaxation.
iii. Glandular cell- may increase or decrease secretion.
Drugs can work to alter these 2 mechanisms. Most neuropharmacological drugs work
to alter synaptic transmissions. Only a few alter axonal conduction.
,Axonal Conduction: Not very selective because conducting an implulse along an axon is the
same in all neurons. Therefore, a drug that alters axonal conduction will affect conduction in all
nerves to which it has access. Cannot produce selective effects.
Example: local anesthetics- work by decreasing axonal conduction and suppress
transmission to any nerve they reach.
Synaptic Transmission: drugs that alter synaptic transmission, produce effects that are highly
selective. Selectivity can occur because synapses, unlike axons differ from one another and
synapses at different sites within the body use different neurotransmitters (hormones). For
most neurotransmitters the body has more than one type of receptor. These drugs have many
uses because of their selectivity.
Step 1: Transmitter synthesis- precursor molecules, which create transmitters must 1 st be
present in the presynaptic nerve terminal.
Step 2: Transmitter storage- after synthesized must be stored until time of release.
Occurs within vesicles (tiny packets) in the axon terminal. Each nerve terminal contains
a large number of transmitter-filled vesicles.
Step 3: Transmitter release- triggered by the arrival of an action potential at the axon
terminal. The action potential starts a process in which vesicles merge with the terminal
membrane. This lets their contents (transmitters) escape into the synaptic gap.
Step 4: Receptor binding- initiates a cascade of events that result in altered behavior of
the postsynaptic cell.
Step 5: Termination of transmission- removal of the transmitter from receptors, then
removal of free transmitter from the synaptic gap. Transmitters are removed from the synaptic
gap by either reuptake (taken back by the cell), enzymatic degradation (broken down by
enzymes), or diffusion (moved around).
The effect of a drug on a neuronally regulated process is dependent on how well it can
directly or indirectly change the activity of the receptors on target cells.
,Receptor activation:
Drugs that MIMIC the effects of natural neurotransmitters INCREASE receptor activation.
Drugs whose effects REDUCE the amount of natural transmitter available for receptor binding
DECREASE receptor activation.
Effects of drugs on the steps of Synaptic Transmission:
1. Transmitter Synthesis: can increase, decrease or cause synthesis of transmitter molecules
that are more effective than the natural transmitter itself.
2. Transmitter Storage: drugs that interfere with storage cause receptor activation to
decrease, disruption of storage depletes vesicles of their transmitters, decreasing the
amount of transmitter available for release.
3. Transmitter Release: drugs can promote or inhibit transmitter release.
a. Drugs that promote release, increase receptor activation.
b. Drugs that inhibit release, reduce receptor activation.
i. Amphetamines- promote transmitter release.
ii. Botulinum Toxin (Botox)- inhibit transmitter release.
4. Receptor Binding: many drugs act directly at receptors by:
a. Binding to receptors and cause activation.
i. Morphine, epinephrine, insulin.
b. Bind to receptors and block/prevent receptor activation by other agents.
i. Naloxone, antihistamines, metoprolol.
c. Bind to receptor components and enhance activation by the natural transmitter at
the site.
i. Benzodiazepines such as diazepam are used to treat anxiety, seizure
disorders, and muscle spasms.
5. Termination of Transmitter Action: drugs can interfere with the termination of a
transmitter action by two mechanisms.
a. Blockade of transmitter reuptake
b. Inhibition of transmitter degradation (the breaking down of transmitter by enzymes).
** Drugs that act by either above mechanism will increase transmitter availability, causing
receptor activation to increase**
Peripheral Nervous System Regulation:
Need to know 3 things to understand PNS drugs:
1. Type or types of receptors through which the drug acts.
2. The normal response to activation of those receptors.
3. What the drug does to the receptor function. Does in increase or decrease receptor
activation?
, Example:
• Isoproterenol is a B1 and B2 Agonist
• Agonist = a substance that initiates a physiological response when combined with a
receptor. Antagonist = a substance that blocks a physiological response.
• It acts on 2 types of adrenergic receptors: B1 and B2.
• When activated, B1 receptors increased HR and Increased force of cardiac
contraction.
• When activated, B2 receptors bronchial dilation and elevation of blood glucose
levels.
• Isoproterenol causes activation of both B1 and B2 adrenergic receptors.
We can now predict the principal effects of this drug. By activating β1 and β2 receptors,
isoproterenol can elicit three major responses: (1) increased cardiac output (by increasing
heart rate and force of contraction), (2) dilation of the bronchi, and (3) elevation of blood
glucose.
Take Home Point: For each PNS drug, you should learn (1) the identity of the receptors at
which that drug acts, (2) the normal responses to activation of those receptors, and (3)
whether the drug increases or decreases receptor activation.
By knowing which receptors drugs target, drug effects are relatively easy to predict.
The nervous system has two main divisions:
1. The central nervous system (CNS)
2. The peripheral nervous system (PNS)
Parasympathetic and Sympathetic Divisions of the PNS:
The PNS has two major subdivisions:
1. The Somatic Motor System: Controls voluntary movement of muscles.
2. The Autonomic Nervous System: further subdivided, both regulate many involuntary
processes.
a. Parasympathetic Nervous System
b. Sympathetic Nervous System
