It gives the brief information about the classification of nervous system, structure of neuron, types of neurons, types of neuroglia, generation of action potential, synapse, neurotransmitters, nerves.

1. Nervous
System
Miss. Rubina U. Watangi. M. Pharm.
Department of Pharmacology
Ms. Rubina U. Watangi, M. Pharm.-Pharmacology 1

2. Classification
of NS
 Somatic
sensations
 Visceral
 sensations
2. General
sensations
Sensory NS
1. Special
sensations
• Brain
• Spinal
cord
PNS
CNS
Nervous System
Motor NS
Somatic
motor
response
• SNS
• PNS
Automatic
motor
response
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3. Functional
components
of nervous
system
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4. Neuron
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5. The
structure of
neurons
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7. • Astrocytes – maintain the blood brain barrier
and preserve the chemical environment by
recycling ions and neurotransmitters
• Oligodendrocytes – myelinate axons in the
central nervous system and provide an overall
structural framework
• Ependymal cells – line ventricles (brain) and
central canal (spine) and are involved in the
production of cerebrospinal fluid
• Microglia – remove cell debris, wastes and
pathogens via phagocytosis
Types of Neuroglia
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8. • Schwann cells – myelinate axons in the
peripheral nervous system
• Satellite cells – regulate nutrient and
neurotransmitter levels around neurons in
ganglia
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9. Neurons and
GlialCells
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Steps of generation of action potential in neurons

11. Conduction
of an
impulse in a
myelinated
nerve fibre.
When an impulse
occurs at one node,
depolarization passes
along the myelin sheath
to the next node so that
the flow of current
appears to ‘leap’ from
one node to the next.
This is called saltatory
conduction
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12. NOTE
 The speed of conduction depends on the
diameter of the neuron: the larger the diameter,
the faster the conduction.
 In addition, myelinated fibers conduct impulses
faster than unmyelinated fibers because
saltatory conduction is faster than continuous
conduction, or simple propagation
 The fastest fibers can conduct impulses to, e.g.,
skeletal muscles at a rate of 130 meters per
second while the slowest impulses travel at 0.5
meters per second.
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13.  The point at which the nerve impulse passes from the
presynaptic neuron to the postsynaptic neuron is the
synapse
 The axon of the presynaptic neuron breaks up into
minute branches that terminate in small swellings
called synaptic knobs, or terminal boutons.
 The space between them is the synaptic cleft/gap.
 Synaptic knobs contain spherical membrane bound
synaptic vesicles, which store a chemical, the
neurotransmitter that is released into the synaptic cleft.
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14. Diagram of a
synapse
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15. Neurotransmitters
 Neurotransmitters are often referred to as the
body's chemical messengers.
 They are the molecules used by the nervous
system to transmit messages between
neurons, or from neurons to muscles.
 Communication between two neurons happens
in the synaptic cleft (the small gap between the
synapses of neurons).
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18. Neurotransmitters
The main difference between excitatory and
inhibitory neurotransmitters is that
 Excitatory neurotransmitters increase the
trans-membrane ion flow of the post-
synaptic neuron, firing an action potential
 Inhibitory neurotransmitters decrease the
trans-membrane ion flow of the post-
synaptic neuron, preventing the firing of an
action potential
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20. Nerves
A nerve consists of numerous neurons collected into
bundles
Bundles of nerve fibers (axon) outside the central
nervous system
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21. Sensory
receptors
Specialized endings of sensory neurons respond to
different stimuli (changes) inside and outside the body.
Somatic, cutaneous or common senses.
 These originate from the skin.
 They are: pain, touch, heat and cold.
 Sensory nerve endings in the skin are fine branching
filaments without myelin sheaths When stimulated, an
impulse is generated and transmitted by the sensory
nerves to the brain where the sensation is perceived.
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22. Proprioceptor senses.
 These originate in muscles and joints.
 Impulses sent to the brain enable perception of the
position of the body and its parts in space maintaining
posture and balance .
Special senses.
 These are sight, hearing, balance, smell and taste
Autonomic afferent nerves.
 These originate in internal organs, glands and tissues,
e.g. baroreceptors involved in the control of blood
pressure, chemoreceptors involved in the control of
respiration
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23. Motor or
efferent
nerves
 Motor nerves originate in the brain, spinal cord and
autonomic ganglia.They transmit impulses to the
effector organs: muscles and glands.
 There are two types:
• somatic nerves – involved in voluntary and reflex
skeletal muscle contraction
• autonomic nerves (sympathetic and
parasympathetic) – involved in cardiac and smooth
muscle contraction and glandular secretion.
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24. Reference
 Waugh, A., & Grant,A. (2009). Ross andWilson: Anatomy
and Physiology in Health and Illness. (11th edition).
Churchill Livingstone
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