The document provides an overview of the human nervous system, detailing its organization, functions, and components including neurons, glial cells, and the division into the central nervous system (CNS) and peripheral nervous system (PNS). Key structures such as the brain, spinal cord, and various types of neurons and glial cells are described along with their specific roles in maintaining homeostasis and facilitating communication within the body. Additionally, it covers the reflex actions and the anatomy of cranial and spinal nerves that connect the CNS to peripheral organs.

1. NERVOUS SYSTEM
Represented by WASIM AKRAM
BSc Nursing
ADWIKA INSTITUTE OF NURSING

2.  INTRODUCTION
 DEFINITION
 ORGANIZATION OF NEURAL SYSTEM
 NEURONS
 GLIAL CELLS
 DIVISION OF NEURAL SYSTEM
 CENTRAL NERVOUS SYSTEM
 BRAIN
 SPINAL CORD
 PERIPHERAL NERVOUS SYSTEM
 CRANIAL NERVES
 SPINAL NERVES
 AUTOMATIC NEURAL SYSTEM
 SYMPATHETIC NEURAL SYSTEM
 PARASYMPATHETIC NEURAL SYSTEM .
CONTENTS

3. INTRODUCTION
 THE FUNCTIONS OF THE ORGANS / ORGAN SYSTEMS
IN OUR BODY MUST BE COORDINATED TO MAINTAIN
HOMEOSTASIS .
 THE NERVOUS SYSTEM MAINTAINS ALL THE NEURAL
CONTROL AND MECHANICAL COORDINATION
THROUGHOUT THE ORGANS AND BODY SYSTEMS .
 THE NEURAL SYSTEM PROVIDES AN ORGANIZED
NETWORK OF POINT TO POINT CONNECTION FOR A
QUICK COORDINATION .
 HERE , WE WILL DISCUSS ABOUT THE HUMAN
NEURAL SYSTEM , MECHANISMS OF NEURAL
COORDINATION LIKE TRANSMISSION OF NERVE
IMPULSE , IMPULSE CONDUCTION ACROSS A
SYNAPSE AND THE PHYSIOLOGY OF REFLEX ACTION .
 This is the most complex and sensitive system in human .

4. DEFINITION
 THE NERVOUS SYSTEM IS DEFINED AS AN ORGAN
SYSTEM CONTAINING A NETWORK OF
SPECIALISED CELLS CALLED NEURONS THAT CO-
ORDINATE THE BODY SYSTEMS AND TRANSMIT
SIGNALS BETWEEN BRAIN AND DIFFERENT PARTS
OF THE BODY .

5. ORGANIZATIONOF
NEURALSYSTEM
 THE NERVOUS SYSTEM IS MADE UP OF NERVOUS
TISSUES .
 THE NERVOUS TISSUES ARE FORMED BY
NEURONS AND NEUROGLIA .
 NEURONS :
NEURONS ARE THE STRUCTURAL AND FUNCTIONAL
UNIT OF NERVOUS SYSTEM .
 NEUROGLIA :
 THESE ARE SUPPORTING CELLS OF THE NERVOUS
SYSTEM .
 THEY PROVIDES PHYSICAL AND METABOLIC
SUPPORT TO THE NEURONS , INCLUDING
NEURONAL INSULATION AND COMMUNICATION .
 THERE ARE THREE TYPES OF GLIAL CELLS :
1. ASTROCYTES
2. OLIGODENDROCYTES
3. MICROGLIAL CELLS .

6. NEURON
 NEURONS ARE THE STRUCTURAL AND
FUNCTIONAL UNIT OF THE NEURAL SYSTEM.
 A NEURON IS A MICROSCOPIC STRUCTURE
COMPOSED OF THREE MAJOR PARTS , NAMELY
CELL BODY , DENDRONS AND AXON .
 CELL BODY :
THE CELL BODY CONTAINS CYTOPLASM WITH TYPICAL
CELL ORGANELLES AND CERTAIN GRANULAR BODIES
CALLED NISSL’S GRANULES .
 DENDRONS :
SHORT FIBRES , REPEATEDLY BRANCHED AND
PROJECT OUT OF THE CELL BODY . ALSO CONTAIN
NISSL’S GRANULES . THESE FIBRES TRANSMIT
IMPULSES TOWARDS THE CELL BODY .
 AXON :
 AXON IS LONG FIBRE , ITS DISTAL PART IS
BRANCHED AND EACH BRANCH TERMINATES AS
SYNAPTIC KNOB WHICH CONTAINS
NEUROTRANSMITTER .
 AXON TRANSMIT IMPULSES AWAY FROM CELL BODY .

7. NEURON

8. TYPESOF
NEURON
 BASED ON THE PRESENCE OF MYELIN SHEATH :
1. MYELINATED : Axon is covered by myelin sheath with
Schwann Cells . Gaps btwn two adjacent myelin sheath is
known as Node of Ranvier . Found in cranial and spinal nerves .
2. NON-MYELINATED : Axon is covered by Schwann cell that
does not form a myelin sheath . Commonly found in ANS &
SNS .
 BASED ON FUNCTION :
1. SENSORY / AFFERENT NEURON : Carry impulses from
organs / body parts to CNS .
2. MOTOR / EFFERENT NEURON : Carry impulses / signals
from CNS to other body parts as a feedback .
 BASED ON THE NUMBER OF AXON & DENDRONS :
1. MULTIPOLAR : One axon & two or more dendrites ; found in
Cerebral Cortex .
2. BIPOLAR : One axon & one dendrite ; found in Retina of Eye .
3. UNIPOLAR : Cell body with one axon only ; found usually in
the embryonic stage .

9. SYNAPSE
 SYNAPSE IS THE JUNCTION BETWEEN TWO
NEURONS .
 THERE ARE THREE TYPES OF SYNAPSE :
1. AXODENDRITIC SYNAPSE
2. AXOAXONIC SYNAPSE
3. AXOSOMATIC SYNAPSE .

10. DIVISIONOF
NEURAL
SYSTEM

11. C
N
S
 THE CNS INCLUDES THE BRAIN AND THE SPINAL
CORD .
 CNS IS THE SITE OF INFORMATION PROCESSING AND
CONTROL .
 THE BRAIN IS THE CENTRAL INFORMATION
PROCESSING ORGAN OF OUR BODY AND ACTS AS THE
COMMAND AND CONTROL SYSTEM .
 THE BRAIN WEIGHING ARROUND 1.4 kg WHICH LIES
WITHIN THE CRANIAL CAVITY .
 OUR BRAIN CONTROLS
 THE VOLUNTARY MOVEMENTS
 BALANCE OF THE BODY
 FUNCTIONING OF VITAL INVOLUNTARY ORGANS ( lungs ,
heart , kidney ) .
 THERMOREGULATION
 HUNGER AND THRUST
 CIRCADIAN (24-hour) RHYTHMS OF OUR BODY
 ACTIVITIES OF SEVERAL ENDOCRINE GLANDS
 HUMAN BEHAVIOUR .
BRAIN

12. BRAIN
 THE BRAIN IS ALSO THE SITE FOR PROCESSING
OF VISSION , HEARING , SPEECH , MEMORY ,
INTELLIGENCE , EMOTIONS & THOUGHTS .
 COVERING OF BRAIN :
 THE HUMAN BRAIN IS WELL PROTECTED BY THE
SKULL 💀 .
 INSIDE THE SKULL , THE BRAIN IS COVERED BY
CRANIAL MENINGES .
 MENINGES CONSISTS OF :
1. DURA MATTER : OUTER LAYER
2. ARACHNOID MATTER : VERY THIN MIDDLE LAYER
3. PIA MATTER : INNER LAYER ; IT IS CONTACT WITH
THE
BRAIN TISSUES .
 SUB-ARACHNOID SPACE :
 THE SPACE BETWEEN ARACHNOID & PIA MATTER .
 THE SUB-ARACHNOID CONSISTS OF CEREBROSPINAL
FLUID ( CSF ) AND MAJOR BLOOD VESSELS .

13. PARTSOFBRAIN
 THE BRAIN CAN BE DIVIDED INTO THREE MAJOR
PARTS :
1. FOREBRAIN ( PROSENCEPHALON )
2. MIDBRAIN ( MESENCEPHALON )
3. HINDBRAIN ( RHOMBENCEPHALON ) .

14. FOREBRAIN
 THE FOREBRAIN CONSISTS OF CEREBRUM,
THALAMUS AND HYPOTHALAMUS .

15. CEREBRUM
 THE CEREBRUM FORMS THE MAJOR PART OF THE
BRAIN .
 A DEEP CLEFT DIVIDES THE CEREBRUM
LONGITUDINALLY INTO TWO HALVES : LEFT
CEREBRAL HEMISPHERE & RIGHT CEREBRAL
HEMISPHERE .
 THE HEMISPHERES ARE CONNECTED BY A TRACT
OF NERVE FIBRES CALLED CORPUS CALLOSUM .
 LOBES OF CEREBRUM :
1. FRONTAL LOBE
2. PARIETAL LOBE
3. TEMPORAL LOBE
4. OCCIPITAL LOBE .
* LIMBIC LOBE / LIMBIC SYSTEM – a complex structure
formed by Inner parts of CH + Amygdala , Hippocampus .

16. 1.
Frontallobe=>

17. 2.
Parietallobe=>

18. 3.
Temporallobe=>

19. 4.
Occipitallobe=>

20. THALAMUS
 THE CEREBRUM WRAPS ARROUND A STRUCTURE CALLED
THALAMUS .
 THALAMUS IS A MAJOR COORDINATING CENTRE FOR
SENSORY AND MOTOR SIGNALING LIKE HEARING , TASTE
, SIGHT & TOUCH . => RELAY STATION .
 FUNCTION :
 SENSORY RELAY CENTER.
 CENTER FOR INTEGRATION OF SENSORY IMPULSES .
 CENTER FOR INTEGRATION OF MOTOR IMPULSES .
 ROLE IN EMOTIONAL ASPECT OF BEHAVIOUR .
 CENTER OF SEXUAL SENSATIONS .
 CENTER OF REFLEX ACTIVITY .
 ROLE IN LANGUAGE .

21. HYPOTHALAMUS
 THIS IS THE MOST IMPORTANT ENDOCRINE PORTION
IN OUR BRAIN LIES AT THE BASE OF THE THALAMUS .
 IT IS ALSO KNOWN AS MASTER OF MASTER GLAND .
 FUNCTION :
 AUTONOMIC FUNCTION :
 Cardiovascular regulation
 Regulation of peristaltic movement of GIT .
 ENDOCRINAL FUNCTION :
 Control of anterior pituitary .
 Regulation of posterior pituitary function .
 Regulation of uterine contractility and regulation of milk ejection .
 CONTROL OF CIRCADIAN RHYTHM ( BIOLOGICAL CLOCK
) .
 REGULATION OF FOOD INTAKE .
 REGULATION OF THIRST MECHANISM .
 The Hypothalamus and Limbic lobe togetherly involve in the
regulation of sexual behaviour , expression of emotional
reactions ( excitement , pleasure , rage & fear ), and motivation .

22. MIDBRAIN
 THE MIDBRAIN IS LOCATED BETWEEN THE
THALAMUS / HYPOTHALAMUS OF THE FOREBRAIN
AND PONS OF THE HINDBRAIN .
 A CANAL CALLED THE CEREBRAL AQUEDUCT
PASSES THROUGH THE MIDBRAIN .
 THE DORSAL PORTION OF THE MIDBRAIN
CONSISTS MAINLY OF FOUR SWELLINGS ( LOBES )
CALLED CORPORA QUADRIGEMINA .
 FUNCTION :
 THE NUCLEI ACT AS RELAY STATION FOR THE
ASCENDING AND DESCENDING NERVE FIBRES .
 THE MIDBRAIN HAVE IMPORTANT ROLES IN
AUDITORY AND VISUAL REFLEXES .

23. HINDBRAIN
 THE HINDBRAIN COMPRISES PONS , CEREBELLUM AND
MEDULLA OBLONGATA .
 BRAIN STEM : THREE MAJOR REGIONS MAKE UP THE
BRAIN STEM ; MIDBRAIN , PONS & MEDULLA
OBLONGATA . BRAIN STEM FORMS THE CONNECTIONS
BETWEEN THE BRAIN AND SPINAL CORD .

24. PONS
 PONS CONSISTS OF FINE TRACTS THAT
INTERCONNECT DIFFERENT REGIONS OF THE BRAIN
.
 THE PONS IS SITUATED ON THE ANTERIOR SURFACE
OF THE CEREBELLUM BELLOW THE MIDBRAIN AND
ABOVE THE MEDULLA OBLONGATA .
 FUNCTION :
 CONNECTING PATHWAY BETWEEN CEREBRAL CORTEX
AND CEREBELLUM .
 PATHWAY FOR ASCENDING AND DESCENDING TRACTS
OF SPINAL CORD AND MEDULLA OBLONGATA .
 JOINING STATION FOR MEDIAL LEMNISCUS WITH
FIBERS OF 5TH , 7TH , 9TH & 10TH CRANIAL NERVES .
 CONTAINS PNEUMOTAXIC AND APNEUSTIC CENTERS
FOR REGULATION OF RESPIRATION .

25. MEDULLA
OBLONGATA
 THE MEDULLA OF THE BRAIN IS CONNECTED TO
THE SPINAL CORD .
 THE MEDULLA OBLONGATA IS CONICAL IN SHAPE
AND CONNECTS THE PONS ABOVE AND SPINAL CORD
BELLOW .
 FUNCTION :
 PATHWAYS FOR ASCENDING AND DESCENDING TRACTS
.
 IT CONTROLS –
 MOVEMENT OF TONGUE
 MOVEMENT OF SHOULDER
 FUNCTION OF VAGUS NERVE
 AUDITORY NERVES .
 HOUSE OF VITAL CENTERS :
 RESPIRATORY CENTER
 VASOMOTOR & CARDIAC CENTER
 DEGLUTITION CENTER
 VOMITING CENTER
 SALIVARY SECRETION CENTER .

26. CEREBELLUM
 CEREBELLUM HAS VERY CONVOLUTED SURFACE
WHICH PROVIDE THE ADDITIONAL SPACE FOR MANY
MORE NEURONS .
 CEREBELLUM IS THE LARGEST PART OF THE
HINDBRAIN , CONTAINS OF TWO LATERAL PARTS
CALLED THE CEREBELLAR HEMISPHERE CONNECTED
IN THE MIDLINE BY A NARROW CENTRAL REGION
CALLED THE VERMIS .
 FUNCTION :
 CONTROL OF BODY POSTURE AND EQUILIBRIUM .
 CONTROL OF MUSCLE TONE AND REFLEXES .
 CONTROL OF VOLUNTARY MOVEMENTS .
 INFLUENCE ON AUTONOMIC SYSTEM .
 CONTROL OF EYEBALL MOVEMENTS .

27. SPINAL
CORD
 THE SPINAL CORD IS LONG BUNDLE OF NERVES AND
CELLS THAT EXTENDS FROM THE LOWER PORTION OF
THE BRAIN TO THE LOWER BACK .
 IT CARRIES SIGNAL BETWEEN THE BRAINS AND THE
REST OF THE BODY PARTS .
 SPINAL CORD ( 42 to 45 cm ) EXTENDS FROM THE
MEDULLA OBLONGATA AND IS CONTINUOUS TO THE
LEVEL OF SECOND LUMBER VERTEBRA .
 IT CONDUCTS IMPULSES TO AND FROM THE BRAIN
AND CONTROLS MOST OF THE REFLEX ACTIVITIES .
 IT IS FORMED OF TWO TYPES OF NEUEAL TISSUES :
INTERNAL GREY MATTER & OUTER WHITE MATTER .
 THE AREA WITHIN THE VERTIBRAL COLUMN BELOW
THE 2ND LUMBER VERTEBRA CONTAINS SPINAL
NERVES THAT ARE COLLECTIVELY CALLED , THE
CAUDA EQUINA .
C
N
S

28. REFLEXACTION
 REFLEX ACTION IS AN IMMEDIATE INVOLUNTARY
ACTION OF ANY ORGAN OR PART OF THE BODY IN
RESPONSE TO A PARTICULAR STIMULUS .
 THE NERVOUS PATHWAY TAKEN BY NERVE
IMPULSES IN A REFLEX ACTION IS CALLED REFLEX
ARC .
 THE COMPONENTS THAT MEDIATE A REFLEX ,
USUALLY INCLUDE :
1. RECEPTOR
2. AFFERENT PATHWAY
3. INTEGRATING CENTRE
4. EFFERENT PATHWAY
5. EFFECTOR
 SOME COMMON EXAMPLES OF REFLEXES ARE :
 CLOSING OF EYES WHEN STRONG LIGHT IS FLASHED
 SALIVATION ON SEEING SIME FAVOURITE FOOD
 PROMPTLY ELEVATION OF HAND FROM FIRE .

29. PERIPHERAL
NEURAL
SYSTEM(PNS)
 THE PNS COMPRISES ALL THE NERVES OF THE BODY
ASSOCIATED WITH THE CNS ( BRAIN & SPINAL CORD ) .
 THE NERVE FIBRES OF THE PNS ARE OF TWO TYPES :
1. AFFERENT FIBRES : The afferent nerve fibres transmit
impulses from tissues / organs to the CNS .
2. EFFERENT FIBRES : The efferent nerve fibres transmit
regulatory impulses from CNS to the concerned peripheral
tissues / organs .
 THE PNS IS DIVIDED INTO TWO DIVISIONS :
1. THE SOMATIC NEURAL SYSTEM RELAYS IMPULSES
FROM THE CNS TO SKELETAL MUSCLE .
2. THE AUTONOMIC NEURAL SYSTEM TRANSMIT
IMPULSES FROM THE CNS TO THE INVOLUNTARY
ORGANS AND SMOOTH MUSCLES OF THE BODY .
 THE NERVES RUNNING OUTSIDE THE BRAIN AND
SPINAL CORD CONSTITUTE PERIPHERAL NEURAL
SYSTEM .
 THESE NERVES ARE OF TWO TYPES :
1. CRANIAL NERVES – 12 pairs
2. SPINAL NERVES – 31 pairs .

30. CRANIAL
NERVES
CRANIAL NERVES ORIGIN FUNCTION
1. OLFACTORY
NERVE
Olfactory epithelium
in nasal cavity
SMELL
2. OPTIC NERVE Retina of eye VISION (Retina of
eye)
3. OCULOMOTOR
NERVE
Floor of midbrain MOVEMENTS OF
EYEBALL
4. TROCHLEAR
NERVE (smallest
cranial nerve )
Floor of midbrain ROTATION OF
EYEBALL
5. TRIGEMINAL
NERVE (largest
cranial nerve )
Ventral surface of
pons varolii
SKIN SENSATION,
TONGUE
MOVEMENTS ,
MASTICATION
6. ABDUCENS
NERVE
Pons varolii Serves lateral rectus
eye muscle (Rotation
of eyeball )
7. FACIAL NERVE
( bears geniculate
ganglion )
Lower part of pons
varolii
Taste , facial
expression, Lacrimal
, chewing (salivation),
movement of neck .

31. CRANIAL
NERVES
CRANIAL NERVES ORIGIN FUNCTION
8. AUDITORY
NERVE
(Vestibulo-cochlear)
Lateral side of pons
varolii
HEARING and
EQUILIBRIUM
9. GLOSSO-
PHARYNGEAL
NERVE
Lateral side of
medulla
Taste, touch,
movement of
pharynx, salivation .
10. VAGUS NERVE
or,
PNEUMOGASTRIC
Longest cranial
nerve – Wandering
Nerve .
Lateral side and
floor of medulla
Vocal cord , lungs,
respiratory reflexes,
peristaltic
movements
swallowing,
secretion of gastric
glands, inhibition of
heart beat .
11. SPINAL
ACCESSORY
NERVES
Both medulla and
spinal cord
Movement of
muscles of Pharynx ,
larynx, neck,
shoulder .
12. HYPOGLOSSAL
NERVE
Ventral side of
medulla oblongata
Movement of tongue
.

32. SPINALNERVES
 THERE ARE 31 PAIRS OF SPINAL NERVES ARISING
FROM EITHER SIDE OF THE SPINAL CORD .
 EACH SPINAL NERVE IS A MIXED NERVE, CONTAINING
BOTH SENSORY AND MOTOR NERVE FIBRES RUNNING
BETWEEN THE SPINAL CORD AND PERIPHERAL
TISSUES.
 SPINAL NERVES ARE CLASSIFIED INTO 5 GROUPS :
1. CERVICAL NERVES – 8 pairs
2. THORACIC NERVES – 12 pairs
3. LUMBER NERVES – 5 pairs
4. SACRAL NERVES – 5 pairs
5. COCCYGEAL NERVES – 1 pairs

33. AUTONOMIC
NEURAL
SYSTEM(ANS)

34. 🤟