Download Human Nervous system

Human Nervous system
Agha Zohaib Khan
What is Nervous System?
The network of nerve cells and fibers that transmits
nerve impulses between parts of the body.
The nervous system is an organ system containing a
network of specialized cells called neurons that
coordinate the actions and transmit signals between
different parts of human body.
In Human nervous system consists of two parts, central
and peripheral. The central nervous system contains the
brain, spinal cord, and retina. The peripheral nervous
system consists of sensory neurons, clusters of neurons
called ganglia, and nerves connecting them to each other
and to the central nervous system.
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Functions of Nervous System
1. Sensory input – gathering information
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To monitor changes occurring inside and
outside the body (changes = stimuli)
2. Integration –
 to process and interpret sensory input and
decide if action is needed.
3. Motor output
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A response to integrated stimuli
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The response activates muscles or glands
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Structural Classification
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Central nervous system (CNS)
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Brain
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Spinal cord
Peripheral nervous system (PNS)
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Nerve outside the brain and spinal cord
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Neurons
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Neurons = nerve cells
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Cells specialized to transmit messages
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Major regions of neurons
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Cell body – nucleus and metabolic center
of the cell
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Processes – fibers that extend from the
cell body (dendrites and axons)
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Neuron- basic structural
unit of the nervous
system
Dendrites- carry
impulses towards the
cell
Axon-carry impulses
away from the cell
Myelin sheath
Synaptic terminal
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Functional Classification of Neurons
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Sensory (afferent) neurons
> Carry impulses from the sensory receptors
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Motor (efferent) neurons
> Carry impulses from the central nervous system
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Central Nervous System
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Cerebrum-largest part
of brain. Responsible
for reasoning, thought,
memory, speech,
sensation, etc.
Divided into two
halves.
Further divided into
lobes; occipital, parietal,
temporal and frontal
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Cerebellum-responsible
for muscle coordination
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Brain stem- most basic
functions; respiration,
swallowing, blood
pressure.
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Medulla Oblongata
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The lowest part of the brain stem
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Merges into the spinal cord
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Includes important fiber tracts
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Contains important control centers
> Heart rate control
> Blood pressure regulation
> Breathing
> Swallowing
> Vomiting
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Spinal cord- begins at
foramen magnum and
ends at second lumbar
vertebrae
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Contains both afferent
(to the brain) and
efferent (motor
neurons- away from the
brain)
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Both the brain and spinal cord are covered by a
membrane system called the meninges
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In addition, the brain has four hollow areas called
ventricles. Cerebrospinal fluid is produced in the
ventricles and baths the brain and spinal column
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Peripheral Nervous System
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The peripheral nervous system (PNS, or occasionally
PeNS) consists of the nerves and ganglia outside of the
brain and spinal cord.
he main function of the PNS is to connect the central
nervous system (CNS) to the limbs and organs.
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Peripheral nervous system
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Somatic system
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12 pairs cranial nerves
31 pairs spinal nerves
Autonomic
is the part of the (PNS)
that acts as a control
system functioning largely
below the level of
consciousness.
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