Anatomy and Physiology of Nervous System

2. FUNCTIONS OF THE NERVOUS SYSTEMFUNCTIONS OF THE NERVOUS SYSTEM
• Sensory input – Gathering information. To
monitor changes occurring inside and outside
the body.
• Integration - To process and interpret sensory
input and decide if action is needed.
• Motor output. A response to stimuli and
Activates muscles or glands.
• The nervous system maintains the homeostasis
of the body.
• Nervous system is a large network of
interconnected systems.

3. CLASSIFICATIONCLASSIFICATION OF THE NERVOUSOF THE NERVOUS
SYSTEMSYSTEM
• Central nervous
system (CNS):
•Brain
•Spinal cord
• Peripheral nervous
system (PNS):
•Nerves outside the
brain and spinal cord

4. THE PERIPHERAL NERVOUS SYSTEMTHE PERIPHERAL NERVOUS SYSTEM
• Sensory (afferent) division - Nerve
fibers that carry information to the
central nervous system.
• Motor (efferent) division - Nerve fibers
that carry impulses away from the
central nervous system.
• Somatic system: They carry
information to somatic effectors
which are skeletal muscles. This
is a motor pathway. This also
include afferent pathways made
of somatic sensory division that
provide feedback. They are
voluntary.
• Autonomic system: Involuntary

5. AUTONOMIC NERVOUSAUTONOMIC NERVOUS
SYSTEMSYSTEMAutonomic nervous system is considered as a self-control
system that comes under peripheral nervous system. It
basically regulates the internal environment of the body,
exchanging commands between peripheral nervous system
and organs in order to maintain important body functions.
There are two divisions in the autonomic nervous system.
Sympathetic nervous system “fight or flight” response. The
main function of the sympathetic nervous system is to
prepare the body for emergency situation and to produce
rapid mobilizations to avoid the danger.
Parasympathetic nervous system. “housekeeping”. This
system is responsible to maintain the activities such as “rest-
and – digest” or “feed- and- breed” that occur when body is at
rest.

6. ENTERIC NERVOUS SYSTEM (ENS)ENTERIC NERVOUS SYSTEM (ENS)
The ENS is also called second brain in the wall of the
gut. The term enteric means intestinal or we call it as
intestinal nervous system.
It is a part of autonomic nervous system.
But it communicates between afferent and efferent
pathways.
It has its own mind and a network of integrators and
feedback loops that act somewhat independently.

7. CLASSIFICATION OF NERVOUS SYSTEMCLASSIFICATION OF NERVOUS SYSTEM

8. NERVOUS SYSTEM HISTOLOGYNERVOUS SYSTEM HISTOLOGY
Neurons = nerve cells
• Cells specialized to transmit electrochemical messages
• Major regions of neurons
• Cell body – nucleus and metabolic center of the cell
• Processes – fibers that extend from the cell body

9. GLIAGLIA
Two main types of cells in nervous system
1.Neurons: they are excitable cells that conduct impulses to
make all nervous system make functional.
2.Glia: they do not conduct impulses but sup[port the
function of neurons in various ways.
a.Neuroglia is derived from glia=glue.
b.Found by Camillo Golgi
c.Unlike neurons it has the capacity of cell division and it
susceptible to cause cancer.
d.Glia mainly consists of 5 types of cells such as Astrocytes,
Microglia, Ependymal cells, Oligodendrocytes, Schwann
cells.

10. GLIAGLIA
Astrocytes: Star shaped cells found in CNS. Largest glia
cells. They feed neurons with lactic acid made from glucose
picked from blood. Helps in production of neurons and
neural connections in the early stage of life. They help to
form Blood Brain Barrier in the capillary network of brain to
prevent the entry of large molecules such as water, alcohol,
CO2 etc.
Microglia: Small stationery cells found in CNS. Does
phagocytosis.
Ependymal cells: Resemble epithelial cells and helps in fluid
circulation around cavities.
Oligodendrocytes: tiny cells found in cluster. They help in
formation of myelin sheath around nerve fibers in CNS.
Schwann cells: or neuro-lemmocytes are the glia of the PNS.
Glial cells function to support neurons and in the PNS.

11. Axon of another
neuron
Axon of another
neuron
Cell BodyCell BodyDendritesDendrites
AxonAxon
Myelin
Sheath
Myelin
Sheath
Dendrites of
another neuron
Dendrites of
another neuron

13. CHARACTERSETICS OF NEURON:CHARACTERSETICS OF NEURON:
•NEURONS ARE LIKE OTHER BODY CELLSNEURONS ARE LIKE OTHER BODY CELLS
• THEY HAVE A CELL MEMBRANE & A NUCLEUS THATTHEY HAVE A CELL MEMBRANE & A NUCLEUS THAT
CONTAINS DNACONTAINS DNA
• SOME WORKING PARTS OF THE CELL KNOWN ASSOME WORKING PARTS OF THE CELL KNOWN AS
ORGANELLES,ORGANELLES,
• THEY CARRY ON PROTEIN SYNTHESIS AND ENERGYTHEY CARRY ON PROTEIN SYNTHESIS AND ENERGY
PRODUCTION.PRODUCTION.
•NEURONS ARE DIFFERENT FROM OTHER BODY CELLS:NEURONS ARE DIFFERENT FROM OTHER BODY CELLS:
• THEY HAVE AN IRREGULAR SHAPE & THEY HAVETHEY HAVE AN IRREGULAR SHAPE & THEY HAVE
SPECIALIZED EXTENSIONS CALLED DENDRITES ANDSPECIALIZED EXTENSIONS CALLED DENDRITES AND
AXONSAXONS
• THEY COMMUNICATE WITH EACH OTHER THROUGHTHEY COMMUNICATE WITH EACH OTHER THROUGH
THE ELECTROCHEMICAL PROCESSTHE ELECTROCHEMICAL PROCESS
• THEY HAVE SOME OTHER SPECIALIZEDTHEY HAVE SOME OTHER SPECIALIZED
STRUCTURES (SUCH AS THE SYNAPSE)STRUCTURES (SUCH AS THE SYNAPSE)
• THEY USE CHEMICALS FOR COMMUNICATIONTHEY USE CHEMICALS FOR COMMUNICATION
CALLED NEUROTRANSMITTERS.CALLED NEUROTRANSMITTERS.

14. STRUCTURE OF NEURONSTRUCTURE OF NEURON
• A DENDRITE IS A STRUCTURE OF THE NEURON THATA DENDRITE IS A STRUCTURE OF THE NEURON THAT
BRINGS INFORMATION TO THE CELL BODY FROMBRINGS INFORMATION TO THE CELL BODY FROM
ANOTHER NEURON. IT HAS A ROUGH SURFACE, WITHANOTHER NEURON. IT HAS A ROUGH SURFACE, WITH
LITTLE BUMPS CALLED DENDRITIC SPINES THATLITTLE BUMPS CALLED DENDRITIC SPINES THAT
INCREASE THE SURFACE AREA OF THE DENDRITEINCREASE THE SURFACE AREA OF THE DENDRITE
SO IT CAN RECEIVE MORE INFORMATION FROM THESO IT CAN RECEIVE MORE INFORMATION FROM THE
NEIGHBORING NEURON. USUALLY THERE ARE MANYNEIGHBORING NEURON. USUALLY THERE ARE MANY
DENDRITES ON EACH CELL, AND DENDRITES DON’TDENDRITES ON EACH CELL, AND DENDRITES DON’T
HAVE MYELIN AS THE AXON DOES. DENDRITESHAVE MYELIN AS THE AXON DOES. DENDRITES
USUALLY BRANCH NEARER TO THE CELL BODY THANUSUALLY BRANCH NEARER TO THE CELL BODY THAN
DOES THE AXON.DOES THE AXON.
• AN AXON CARRIES INFORMATION AWAY FROM THEAN AXON CARRIES INFORMATION AWAY FROM THE
CELL BODY TO THE DENDRITES OF A NEIGHBORINGCELL BODY TO THE DENDRITES OF A NEIGHBORING
NEURON OR TO ANOTHER BODY STRUCTURE SUCHNEURON OR TO ANOTHER BODY STRUCTURE SUCH
AS A MUSCLE. AXONS HAVE SMOOTH SURFACESAS A MUSCLE. AXONS HAVE SMOOTH SURFACES
AND NO SPINES LIKE DENDRITES HAVE. MOSTAND NO SPINES LIKE DENDRITES HAVE. MOST
NEURONS HAVE ONLY ONE AXON, AND THE AXONNEURONS HAVE ONLY ONE AXON, AND THE AXON
BRANCHES FURTHER FROM THE BODY THAN THEBRANCHES FURTHER FROM THE BODY THAN THE
DENDRITE DOES.DENDRITE DOES.

15. NEURON ANATOMYNEURON ANATOMY
• Dendrites – conduct impulses
toward the cell body
• Telo-dendria: the distal tip
axon that end in synaptic nobe.
• Cell body (soma): also called
perikaryon. It contains
organelles & substance
(specialized rough ER)
• Axons – conduct impulses
away from the cell body
• Schwann cells – produce
myelin sheaths in jelly-roll like
fashion
• Nodes of Ranvier – gaps in
myelin sheath along the axon

16. AXONS.AXONS.
• IF AN AXON HAS MYELIN, THE INFORMATION ITIF AN AXON HAS MYELIN, THE INFORMATION IT
SENDS CAN TRAVEL FASTER THAN IF THE AXONSENDS CAN TRAVEL FASTER THAN IF THE AXON
DOES NOT HAVE MYELIN.DOES NOT HAVE MYELIN.
• MYELIN IS PRODUCED BY SUPPORT CELLS IN THEMYELIN IS PRODUCED BY SUPPORT CELLS IN THE
NERVOUS SYSTEM CALLED GLIA. MYELINATIONNERVOUS SYSTEM CALLED GLIA. MYELINATION
AFFECTS THE SPEED OF NEURAL TRANSMISSION.AFFECTS THE SPEED OF NEURAL TRANSMISSION.
• THERE ARE BREAKS AT VARIOUS POINTS IN THETHERE ARE BREAKS AT VARIOUS POINTS IN THE
MYELIN THAT SURROUNDS THE AXON, AND THESEMYELIN THAT SURROUNDS THE AXON, AND THESE
BREAKS ARE CALLED NODES OF RANVIER.BREAKS ARE CALLED NODES OF RANVIER.
• AS AN ELECTRICAL SIGNAL, CALLED AN ACTIONAS AN ELECTRICAL SIGNAL, CALLED AN ACTION
POTENTIAL, TRAVELS DOWN THE AXON, THE ACTIONPOTENTIAL, TRAVELS DOWN THE AXON, THE ACTION
POTENTIAL “JUMPS” FROM NODE TO NODE.POTENTIAL “JUMPS” FROM NODE TO NODE.
• THIS JUMPING ALLOWS THE SIGNAL TO TRAVELTHIS JUMPING ALLOWS THE SIGNAL TO TRAVEL
MUCH FASTER THAN IT WOULD BE ABLE TO IF ITMUCH FASTER THAN IT WOULD BE ABLE TO IF IT
HAD TO TRAVEL ALONG AN AXON WITHOUT MYELIN.HAD TO TRAVEL ALONG AN AXON WITHOUT MYELIN.
• THIS TYPE OF MOVEMENT BY AN ACTION POTENTIALTHIS TYPE OF MOVEMENT BY AN ACTION POTENTIAL
ALONG AN AXON WITH MYELIN IS CALLEDALONG AN AXON WITH MYELIN IS CALLED

17. Types of Neurons
Sensory Motor Interneurons

18. MOTOR NEURONMOTOR NEURON

19. SENSORY NEURONSENSORY NEURON

22. NEURONSNEURONS
Figure 7.6

27. NEURON FUNCTIONNEURON FUNCTION

29. ELECTRICAL NATURE OF NEURONSELECTRICAL NATURE OF NEURONS

30. ELECTRICAL NATURE OF NEURONSELECTRICAL NATURE OF NEURONS

31. • When a stimulus is applied to a neuron the stimulus
gated Na+ channel open. Na+ diffuse rapidly into the
cell because of the concentration gradient and electrical
gradient producing local depolarization.
• When the magnitude of the local depolarization
surpasses the limit called threshold potential Voltage
gated channels of Na+ open. They are ion channels
that respond to voltage changes. There are many Na+
and K+ channels in the membrane of the neuron.
• As more Na+ rushes into the cell the membrane moves
rapidly toward 0mV and then continues in a positive
direction to a peak of +30mV. + indicate that there are
excess positive ions inside the membrane.

32. • Voltage gated channels stay open for only about 1
milliseconds before they automatically closes. It is automatic
and happens if and only if the threshold potential is
surpassed otherwise no action potential created.
• Once the peak action potential is reached the membrane
potential begins to move back towards resting potential
which called repolarization. (-70mV). Surpassing the
threshold potential not triggers Na+ channel but also K+
channel. The K+ channel is slow to respond but still it helps
in the outflow of the excess positive ions thus repolarizing
the membrane.
• Since the K+ channel often remain open as the membrane
reaches its resting potential, too much K+ ions may rush out
thus there is a period of hyperpolarization before the resting
potential is restored and K+ channel closes.

34. REFRACTORY PERIODREFRACTORY PERIOD

35. CONDUCTION OF THE ACTIONCONDUCTION OF THE ACTION
POTENTIALPOTENTIAL

36. CONDUCTION OF THE ACTIONCONDUCTION OF THE ACTION
POTENTIALPOTENTIAL

37. SYNAPTIC TRANSMISSIONSYNAPTIC TRANSMISSION

38. TYPES OF SYNAPSETYPES OF SYNAPSE

39. TYPES CONTD….TYPES CONTD….
Multiple ways of
connecting
1.Axon to Dendrite –
excite or inhibit neuron
2.Axon to Axon Terminal
– moderate NT releases
3.Axon to Extracellular
Space or blood –
potential for diffuse
effects

40. MECHANISM OF SYNAPTICMECHANISM OF SYNAPTIC
TRANSMISSIONTRANSMISSION

41. MECHANISM OF SYNAPTICMECHANISM OF SYNAPTIC
TRANSMISSIONTRANSMISSION

42. SYNAPSE FUNCTIONSYNAPSE FUNCTION

43. SYNAPSES AND MEMORYSYNAPSES AND MEMORY

44. NEUROTRANSMITTER TYPESNEUROTRANSMITTER TYPES

45. NEUROTRANSMITTER TYPESNEUROTRANSMITTER TYPES

48. Figure 9-4b

49. Figure 9-4b

50. Figure 9-4b

51. Figure 9-4b

56. Figure 9-6: The blood-brain barrier

57. Figure 9-6: The blood-brain barrier

69. http://www.driesen.com/diencephalon.htm

89. Figure 9.8

97. neuroscienceMizanneuroscienceMizan

101. neuroscienceMizanneuroscienceMizan

110. LUMBAR PLEXUSLUMBAR PLEXUS

111. SACRAL PLEXUS & COCCYGEAL PLEXUSESSACRAL PLEXUS & COCCYGEAL PLEXUSES

117.  Component: Sensory
 Function: Smell
 Opening to the Skull: Openings in
cribriform plate of Ethmoid (facial
bone)
 Origin: Olfactory receptor nerve cells

119.  Component: Sensory
 Function: Vision
 Opening to the Skull: Optic
Canal/foramina
 Origin: Back of the eyeball

121.  Component: Motor
 Function:
 Raises upper eyelid
 Turns eyeball upward, downward and
medially
 Constricts pupil
 Accommodates the eye
 Opening to the Skull: Superior orbital fissure
 Origin: Anterior surface of the midbrain

123.  Component: Motor
 Function: Assisting in turning eyeball
downward and laterally
 Opening to the Skull: Superior orbital fissure
 Origin: Posterior surface of the midbrain

125.  Component: Sensory
 Function:
 Cornea
 Skin of forehead
 Scalp
 Eyelids and nose
 Mucous membranes of paranasal
sinuses and nasal cavity
 Opening to the Skull: Superior orbital fissure
 Origin: Anterior aspect of the pons

126. o Component: Sensory
o Function:
o Skin of the face over maxilla
o Teeth of the upper jaw
o Mucous membrane of the nose, the
maxillary sinus and palate
o Opening to the Skull: Foramen ovale
o Origin: Anterior aspect of the pons

127. o Component: a. Motor
o Function:
o Muscles of mastication
o Mylo-hyoid: muscle from mandible to hyoid
forming the floor of the mouth
o Anterior belly of digastric: muscle under the jaw
o Tensor tympani: is a muscle within the ear. It is
contained in the auditory tube. Its role is to
decrease sounds, such as those produced from
chewing.
o Opening to the Skull: Foramen Rotundum
o Origin: Anterior aspect of the pons

128. • Component: b. Sensory
• Function:
• Skin of cheek
• Skin over mandible and side of head
• Teeth of lower jaw and TMJ
• Mucous membrane of mouth and anterior
part of tongue
• Opening to the Skull: Foramen Rotundum
• Origin: Anterior aspect of the pons

130.  Component: Motor
 Function: Lateral rectus muscle turns eyeball
laterally
 Opening to the Skull: Superior orbital fissure
 Origin: Anterior Surface of hindbrain
between pons and medulla

143. Feature Somatic Motor
Pathways
Autonomic Pathways
Direction of flow Efferent Efferent
No. of neurons
between CNS
and effectors
One Two
Pre-ganglionic
Post ganglionic
Myelin sheath Present Pre-ganglionic: Present
Post ganglionic: Absent
Effectors Skeletal
Muscles
Smooth muscles, cardiac
etc.

168. Hydrocephalus

181. FLEXOR (WITHDRAWL) REFLEXFLEXOR (WITHDRAWL) REFLEX
IT IS A SPINAL REFLEX, AT
THE TIME OF INJURY. THIS
PULLS AWAY FROM THE
PAINFUL STIMULI. THIS IS
ALSO CALLED FLEXOR
REFLEX BECAUSE FLEXOR
MUSCLE OF THE UPPER
EXTREMITY IS INVOLVED
IN IT. A PAINFUL
STIMULUS CAN TRIGGER
BOTH IPSILATERAL (SAME
SIDE) AND
CONTRALETERAL
(OPPOSITE SIDE)
STABILIZE OF THE BODY
WEIGHT . THIS IS ANTHIS IS AN