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1. NERVOUS
SYSTEM

2. CONTENT
oINTRODUCTION OF NERVOUS SYSTEM
oORGANIZATION OF NERVOUS SYSTEM
oNERVOUS TISSUE
oNEURONS AND ITS TYPES
oSUPPORTING CELLS
oASCENDING TRACT AND DESCENDING TRACT
oREFLEX

3. INTRODUCTION
• NERVOUS SYSTEM IS:
A PHYSICALLY CONNECTED NETWORK OF CELLS, TISSUES AND ORGANS
THAT ALLOW US TO COMMUNICATE WITH AND REACT TO THE
ENVIRONMENT AND PERFORM LIFE ACTIVITIES.
MASTER CONTROLLING AND COMMUNICATING SYSTEM
• HAS TWO MAIN DIVISION
• CENTRAL NERVOUS SYSTEM
• PERIPHERAL NERVOUS SYSTEM

4. FOUR PRIMARY FUNCTIONS OF
NERVOUS SYSTEM
SENSING THE WORLD
VISION, HEARING, SMELL,
TASTE, TOUCH
TRANSMITTING INFORMATION
PROCESSING INFORMATION
PRODUCING A RESPONSE

5. ORGANIZATION
A. Central Nervous System (CNS)
▫ Brain & spinal cord
▫ Integrative and control centers
-Receives, interprets and sends signals to PNS
B. Peripheral Nervous System (PNS)
▫ Nerves (31 pairs of spinal nerves,12 pairs of cranial nerves)
▫ Communication lines between CNS and rest of body
▫ Two Divisions:
1. Sensory (afferent) Division: Sensory receptors --
CNS
2. Motor (efferent) Division: CNS -- effectors (muscles &
glands)

6. MOTOR DIVISION
• SOMATIC NERVOUS SYSTEM (VOLUNTARY)
- CONTROL SKELETAL MUSCLES
• AUTONOMIC NERVOUS SYSTEM (ANS) (INVOLUNTARY)
– REGULATE SMOOTH MUSCLES, CARDIAC, GLANDS
▫ SUBDIVISIONS:
o SYMPATHETIC :
o “FIGHT OR FLIGHT”
o ACTIVATED DURING EMERGENCIES, EXERCISE OR VIGOROUS PHYSICAL ACTIVITY
o REVS UP BODY TO RESPOND TO SITUATIONS THAT UPSET HOMEOSTASIS
o PARASYMPATHETIC:
o “REST & DIGEST”
o REDUCES ENERGY USE
o PROMOTES:
o STORAGE OF ENERGY
o ELIMINATION OF WASTES
o HOMEOSTASIS

10.  The mammalian brain is highly
complex, containing many
specialized regions that carry
out specific functions.
 Generally, the brain is divided
into:
 Hindbrain
 Midbrain
 Forebrain
THE COMPLEX BRAIN

11. HINDBRAIN
MEDULLA:
 CONTROLS AUTONOMIC
FUNCTIONS.
PONS:
 CONTROLS SLEEP STAGES.
CEREBELLUM:
 COORDINATES MOVEMENT, STORES
SOME MOTOR MEMORY.
 HELPS MAINTAIN POSTURE,
MUSCLE CONTROL, AND BALANCE

12. MIDBRAIN
• LOCATED BETWEEN THE HINDBRAIN AND FOREBRAIN.
• ALL SENSORY AND MOTOR INFORMATION THAT TRAVELS
BETWEEN THE FOREBRAIN AND THE SPINAL CORD
PASSES THROUGH THE MIDBRAIN
• MAKING IT A RELAY STATION FOR THE CENTRAL
NERVOUS SYSTEM.
• THE “TRAFFIC COPS” OF THE BRAIN.
• FILTERS SENSORY INPUT, WHICH ALLOWS US TO
CONCENTRATE.
• FILTERING CAN BE AFFECTED BY HIGHER THOUGHTS.

13. FOREBRAIN
THALAMUS:
 RELAY STATION CHANNELING
SENSORY INFORMATION.
LIMBIC SYSTEM:
 BASIC EMOTIONS, DRIVES, AND
BEHAVIORS.
CORTEX:
 HIGHER THOUGHT

14. LIMBIC SYSTEM
HYPOTHALAMUS:
MASTER CONTROLLER OF THE
ENDOCRINE SYSTEM.
AMYGDALA:
SENSATIONS OF PLEASURE OR
FEAR, RECOGNITION OF FEAR
IN OTHERS.
HIPPOCAMPUS:
FORMATION OF MEMORIES.
Damage to these areas can lead to amnesia or
emotional disturbances
“controls: emotions and memories”

15. CORTEX
 VARIOUS AREAS :
 CONTROL
SENSORY
PROCESSING
 MOTOR
CONTROL,
 THOUGHT,
 MEMORY.
Top layer of the brain
Stores: experiences and/or learning
behavior & emotion
Sensory info
concerning touch
vision
memory & emotion,
speech and hearing

16. SPINAL CORD
•GREY MATTER
–MOSTLY MADE UP OF CELL BODIES OF NEURON
•WHITE MATTER
–COMPOSED OF NERVE FIBERS ( ASCENDING AND
DESCENDING TRACTS ) EMBEDDED IN NEUROGLIAL CELLS

18. NERVOUSTISSUE
1. NEURONS (NERVE CELLS)
• FUNCTIONAL UNIT OF THE NERVOUS SYSTEM
• TRANSMIT MESSAGE
ANATOMY:
CELL BODY – CONTAINS NUCLEUS; METABOLIC
CENTER
DENDRITE – FIBER THAT CONVEYS MESSAGES
TOWARD CELL BODY
AXON – CONDUCT NERVE IMPULSES AWAY FROM
THE CELL BODY
AXON TERMINALS – END OF AXON; CONTAIN
NEUROTRANSMITTERS& RELEASE THEM
SYNAPTIC CLEFT/SYNAPSE – GAP BETWEEN NEURONS

20. NERVOUSTISSUE
2. SUPPORTING CELLS (NEUROGLIA)
CNS: ASTROCYTES, MICROGLIA, EPENDYMAL CELLS,
OLIGODENDROCYTES
BARRIER BETWEEN CAPILLARIES AND NEURONS
PROTECT NEURONS
IMMUNE/DEFENSE
LINE BRAIN AND SPINAL CORD CAVITIES
WRAP NERVE FIBERS
PRODUCES MYELIN SHEATHS (COVERING)
PNS: SCHWANN CELLS, SATELLITE CELLS
SURROUND LARGE NEURONS PROTECT & CUSHION

22. Myelin
 Whitish, fatty material that covers nerve fibers to
speed up nerve impulses
Schwann cells
 Surround axons and form myelin sheath
Myelin sheath
• Tight coil of wrapped membranes
Nodes of Ranvier
 Gaps between Schwann cells

23. • Ganglia: collections of cell bodies
• Bundles of nerve fibers = tracts (CNS) or nerves (PNS)
• White matter
• Dense collections of myelinated fibers
• Gray matter
• Unmyelinated fibers & cell bodies
• (nerve cell bodies, dendrites, axon terminals, bundles of
unmyelinated axons and neuroglia (gray color)

24.  Dendrites receive signals.
 The cell body integrates
signals.
 The axon transmits action
potential. The myelin sheath
makes the signal travel
faster.
 Synaptic terminals transmit
signals.
The Neuron

25. NEURONS
• NEURON FUNCTION
• IRRITABILITY:
• ABILITY TO RESPOND TO STIMULUS &
CONVERT TO NERVE IMPULSE
• CONDUCTIVITY:
• TRANSMIT IMPULSE TO OTHER NEURONS,
MUSCLES, OR GLANDS
• CLASSIFICATION OF NEURON
• FUNCTIONAL CLASSIFICATION
• STRUCTURAL CLASSIFICATION

26. 1. FUNCTIONAL CLASSIFICATION:
DIRECTION NERVE IMPULSE IS TRAVELING
Sensory
neurons
Motor
neurons
Interneurons
carry impulses from
sensory receptors to
CNS
carry impulses from
CNS to muscles &
glands
connect sensory &
motor neurons
Vision, hearing,
equilibrium, taste,
smell, pain,
pressure, heat

27. 2. STRUCTURAL CLASSIFICATION:
PROCESSES EXTENDING FROM CELL BODY
Multipolar Bipolar Unipolar
1 axon, several
dendrites
1 axon, 1 dendrite 1 process
Most common
(99%)
Rare
Short with 2
branches (sensory,
CNS)
Eg. Motor
neurons,
interneurons
Eg. retina, nose,
ear
Eg. PNS ganglia

29. NERVE IMPULSES
• CELL MEMBRANE AT REST = POLARIZED
NA+OUTSIDE CELL, K+INSIDECELL
INSIDE IS (-) COMPARED TO OUTSIDE
• STIMULUS ---EXCITED NEURON (NA+RUSHES IN)
--BECOMES DEPOLARIZED
• DEPOLARIZATION ACTIVATES NEURON TO
TRANSMIT AN ACTION POTENTIAL (NERVE
IMPULSE)
ALL-OR-NONE RESPONSE
IMPULSE CONDUCTS DOWN ENTIRE
AXON
• K+ DIFFUSES OUT ---REPOLARIZATION OF
MEMBRANE
• NA+/K+ ION CONCENTRATIONS RESTORED BY
SODIUM- POTASSIUM PUMP (USES ATP)
Exciting aNeuron

31. REFERENCES
• ELAINE N. MARIEB, HUMAN ANATOMY AND PHYSIOLOGY 9TH EDITION .
• DR. HENRY GRAY AND DR. HENRY VANDYKE CARTER , GRAYS ANATOMY
FOR STUDENTS 40TH EDITION.
• VARIOUS INTERNET SOURCES.