1. The nervous system is divided into the central nervous system and peripheral nervous system. The central nervous system is the brain and spinal cord, and the peripheral nervous system includes cranial and spinal nerves. 2. Neurons conduct electrical and chemical signals to transmit information, while glial cells provide support to neurons. Myelination affects how fast impulses are conducted along neurons. 3. Neurotransmitters are released at synapses to chemically transmit signals between neurons. The signal can be excitatory and increase the chance of firing an action potential, or inhibitory and decrease excitability.

1. NeuropharmacologyNeuropharmacology
(Central Nervous(Central Nervous
System)System)

2. Nervous system:
Central nervous system (CNS): brain and spinal
cord
Peripheral nervous system (PNS): cranial
nerves and spinal nerves
somatic- skeletomuscular sysem
autonomic- internal organs
sympathetic
parasympathetic
Two types of cells: neurons and supporting
(glial) cells

3. Types of neurons:
Interneuron- located entirely within CNS,
integrates functions in CNS
Sensory (from sensory receptor to CNS)
Motor (from CNS to effector organ)
somatic- stimulates skeletal muscles
autonomic- affects smooth and cardiac
muscle, also glandular secretion
Nerve- bundle of neurons (axons)
Ganglion- bundle of nerve cell bodies outside
of CNS
Nucleus- within CNS
Tract- connects regions of CNS

6. Parts of a neuron
Cell body- contains the nucleus and other
organelles
Dendrites- transmit electrical impulses TO the
cell body
Axon- transmits impulse AWAY from the cell body
axons can be several feet long
“Axonal hillock” is located near the cell body
nerve impulses originate there

7. Structures of neurons
sensory
motor
retina

8. Supporting cells
Schwann cells, oligodendrocytes- produce
myelin
Satellite cells- support neurons in PNS
Microglia-phagocytes in CNS
Astrocytes- induces blood-brain barrier
Ependymal cells- special epithelium that line
brain ventricles and central canal of
spinal cord
also part of structure that makes CSF

11. Large axons are myelinated by Schwann cells
or oligodendrocytes
Gaps are left between the “wrappings” of each
cell (nodes of Ranvier)
Myelinated axons conduct nervous impulses
more rapidly than unmyelinated
In CNS, myelinated axons form “white matter”
(Cell bodies and dendrites are gray matter)

12. Schwann cells can help repair damaged nerves
Capacity for repair is much better in the
periphery
In fetal brain, neurotropins promote neuron
growth
Some factors help maintain neural structures
in adult nervous systems
Some inhibitory factors also

13. Astrocytes
Most common glial cell in CNS
Form blood-brain barrier
Help with ion uptake
Help with neurotransmitter uptake
Many glucose transport carriers, which help
move glucose from blood to brain

14. Blood-brain barrier (BBB)
Probably due to effects of astrocytes on brain
capillaries
Everything must move into brain by diffusion
and active transport
Many substances (including therapeutic drugs)
cannot cross BBB

15. Electrical activity in axons
Resting membrane potential in neurons
is –70 mV
Large negatively charged molecules inside
the cell
Positively charged ions outside the cell
(more Na out than K in)
Neurons are excitable: they can change their
membrane potential in response to
stimulation

16. Permeability to ion changes
Occurs in a very small area on the membrane
Depolarization- potential difference approaches
zero
Repolarization- back to the resting potential
Hyperpolarization- potential difference increases
positive charges leave cell
negative charges enter cell

17. Gated ion channels for K and Na
(lots of these at axon hillock)
Resting cell is more permeable to K than Na
Depolarization- membrane becomes permeable
to Na, and Na can diffuse into cell
After Na gates close, K gates open and K diffuses
out of the cell

19. Action potentials are very rapid
Inactivation occurs until membranes are
repolarized (by sodium-potassium pumps)
Stronger stimuli stimulate more and more axons
(more action potentials are stimulated, but
their amplitude does not change)

20. Refractory period
When an action potential is being produced, a
second stimulus will not affect that part
of the membrane
Stimulus when K gates are open and membranes
are repolarizing
Relative refractory period- a very strong stimulus
can overcome repolarizing

22. Synapse- connection between a neuron and
a second cell
From presynaptic to postsynaptic neuron
Release of neurotransmitters (chemicals)
A few electrical synapses in nervous system,
In smooth muscle and heart
gap junctions

23. Chemical synapses
One-way
Presynaptic neuron has synaptic vesicles
Fusion of vesicles is mediated by calcium
Calmodulin is activated
Protein kinase activated
Synaptic vesicles fuse with membrane
Neurotransmitters diffuse across cleft and
bind to receptors

25. Voltage-regulated channels in presynaptic axon
Chemically regulated channels in
postsynaptic membrane
Ion channels are opened, depolarization occurs
Can be excitatory or inhibitory
Depends on which receptors are engaged
Integration of impulses in dendrites and cell
body of postsynaptic neuron

26. Criteria for establishing a molecule as aCriteria for establishing a molecule as a
neurotransmitterneurotransmitter
 synthesissynthesis
 the molecule is synthesized in the presynaptic neuronsthe molecule is synthesized in the presynaptic neurons
 localizationlocalization
 the molecule is present in the presynaptic terminalthe molecule is present in the presynaptic terminal
 releaserelease
 the molecule is released upon stimulation of the presynaptic neuronthe molecule is released upon stimulation of the presynaptic neuron
 mimicrymimicry
 when applied exogenously (e.g., from a micropipette), inwhen applied exogenously (e.g., from a micropipette), in
concentrations similar to those observed following stimulation ofconcentrations similar to those observed following stimulation of
the presynaptic cellthe presynaptic cell
 the molecule mimics the action of the endogenously releasedthe molecule mimics the action of the endogenously released
transmittertransmitter
 inactivationinactivation
 a specific mechanism or a set thereof exists to remove the moleculea specific mechanism or a set thereof exists to remove the molecule
from the synaptic cleft or to degrade itfrom the synaptic cleft or to degrade it

27. Acetylcholine
Excitatory to some neurons in CNS and motor
neurons
Inhibitory to others
Different cells have different types of receptors
Nicotinic- stimulatory; nicotine also binds
skeletal muscle fibers, autonomic ganglia
Muscarinic- muscarine also binds
smooth and cardiac muscle; glands

28. Ion channel most direct type of activation
EPSP (excitatory postsynaptic potential)
no threshold
can be graded (number of stimulated
receptors)
no refractory period
summation: effect of several EPSPs added
(i.e., graded)

29. Muscarinic receptors- operated by G proteins
Three subunits to G protein, different ones
can be effectors
Tends to have in inhibitory effect (IPSP)

30. Why inhibitory?
K+ diffuses out, causing hyperpolarization
Both EPSPs and IPSPs can be produced
voluntarily- summate or cancel each
other out

31. Acetylcholinesterase (AChE)
Inactivates ACh. Otherwise ACh-receptor
complexes would keep forming.

33. In PNS ACh stimulates muscles to contract
In ANS: sympathetic and parasympathetic
nerves
Effect depends on whether nicotinic or
muscarinic receptors are activated
If EPSPs are above threshold an action
potential will be generated along the axon

34. Monoamines as neurotransmitters
Monoamines
dopamine
norepinephrine
serotonin
Tend to be stimulatory; must be quickly inhibited
to maintain control

35. Control mechanisms:
Uptake of monoamines by presynaptic neuron
Degradation by monoamine oxidase in
presynaptic neuron
By post-synaptic neuron (COMT*, degrades
catecholamines)
COMT= catechol-O-methyltransferase

36. Monoamines act through second messenger
(cAMP)
Catecholamines
norepinephrine- hormone and neuro-
transmitter
controlled by:
reuptake
monoamine oxidase (MAOIs inhibit this)
COMT in postsynaptic neuron

38. Serotonin
derived from tryptophan
affects specific cells in brain stem
regulates mood and behavior, appetite,
cerebral circulation
SSRIs- serotonin-specific reuptake inhibitors
increase effect of serotonin
antidepressants
May have different effects depending on
receptor

39. Dopamine
dopaminergic cells located in midbrain
effects on motor and emotional function
Nigrostriatal- motor; in substantia nigra
Parkinson’s disease- degeneration of these
neurons
L-DOPA and MAO inhibitors- increase dopamine
transmission

40. Drugs relieve symptoms for awhile, but do not
stop killing of neurons
Growth factors?
Transplants? (fetal cell, xenotransplants, auto-
transplants of carotid body cells, etc.)
Areas of research:
what exactly is the problem
interaction with other neurotransmitters
effects on other parts of the brain (in
mood, behavior, physical activity, etc.)

41. Summary
1. The nervous system is comprised of the
central nervous system (brain, spinal cord)
and the periphery (cranial and spinal nerves)
Periphery is divided into autonomic and motor
neurons.
2. Cells of the nervous system are glial cells and
neurons. Neurons conduct nervous impulses,
glial cells “support” neurons.
3. Myelination affects the speed at which impulse
is delivered.

42. 4. Neurons conduct electrical and chemical
signaling. Action potential starts at a very
small area of the membrane and is conducted
along the length of the membrane.
Action potential rises with Na influx and falls
with K efflux.
5. Speed of transmission is affected by a.) presence
of myelin, and b.) the diameter of the neuron.
(faster in larger neurons)
6. Neurotransmitters deliver signals across
synapses.

43. 7. Sometimes signal is excitatory, sometimes
inhibitory.
Excitatory: receptors serve as ion channels,
depolarizes, brings closer to threshold.
Inhibitory: causes hyperpolarization
A given synapse is always one or the other.
Some act as second messengers (more
long-term effects).
8. Neurotransmitters are typically small fast-
acting molecules. Some are larger and
slower-acting than others
learning, motivation, response to stress, etc.

44. 9. Long-term potentiation: if a neuron is
stimulated once, synaptic transmission
is more efficient thereafter
May favor use of certain neural pathways:
“learning”
10. Some transmitters are inhibitory.
Postsynaptic: GABA and glycine
Presynaptic: interference with axon
interferes with calcium influx