This document provides an overview of the nervous system, including its main components and functions. It discusses the central nervous system (CNS), which includes the brain and spinal cord. It also discusses the peripheral nervous system (PNS), which is divided into the somatic and autonomic nervous systems. The autonomic nervous system has two divisions - the sympathetic and parasympathetic nervous systems, which work in opposition to control involuntary body functions. Key cell types and the structures of the brain, spinal cord, and nerves are also summarized.

1. BIOMEDICAL INSTRUMENTS
SUBMITTED BY:
DIVYA SHARMA (110170117007)
HARSHITA SHAH (110170117023)
SUBMITTED TO:
PROF. R.K. SHUKLA
(ASSISTANT PROFESSOR)

2. TOPIC: “NERVOUS SYSTEM”

3. CONTENT
 ORGANIZATION OF THE NERVOUS SYSTEM
 THE NEURON
 CENTRAL NERVOUS SYSTEM
 PERIPHERAL NERVOUS SYSTEM
 AUTONOMIC NERVOUS SYSTEM

4. GENERAL ORGANIZATION OF THE NERVOUS
SYSTEM
TWO ANATOMICAL DIVISIONS
 CENTRAL NERVOUS SYSTEM (CNS)
• BRAIN
• SPINAL CORD
 PERIPHERAL NERVOUS SYSTEM (PNS)
• ALL THE NEURAL TISSUE OUTSIDE CNS
• AFFERENT DIVISION (SENSORY INPUT)
• EFFERENT DIVISION (MOTOR OUTPUT)
o SOMATIC NERVOUS SYSTEM
o AUTONOMIC NERVOUS SYSTEM

5. GENERAL ORGANIZATION OF THE NERVOUS
SYSTEM

6. HISTOLOGY OF NEURAL TISSUE
• TWO TYPES OF NEURAL CELLS IN THE NERVOUS SYSTEM:
 NEURONS - FOR PROCESSING, TRANSFER, AND STORAGE OF INFORMATION
 NEUROGLIA – FOR SUPPORT, REGULATION & PROTECTION OF NEURONS

7. NEUROGLIA (GLIAL CELLS)
• CNS NEUROGLIA:
• ASTROCYTES
• OLIGODENDROCYTES
• MICROGLIA
• EPENDYMAL CELLS
• PNS NEUROGLIA:
• SCHWANN CELLS (NEUROLEMMOCYTES)
• SATELLITE CELLS

8. NEURON STRUCTURE

9. •MOST AXONS OF THE NERVOUS
SYSTEM ARE SURROUNDED BY A
MYELIN SHEATH (MYELINATED
AXONS)
•THE PRESENCE OF MYELIN SPEEDS
UP THE TRANSMISSION OF ACTION
POTENTIALS ALONG THE AXON
•MYELIN WILL GET LAID DOWN IN
SEGMENTS (INTERNODES) ALONG
THE AXON, LEAVING
UNMYELINATED GAPS KNOWN AS
“NODES OF RANVIER”
•REGIONS OF THE NERVOUS
SYSTEM CONTAINING GROUPINGS
OF MYELINATED AXONS MAKE UP
THE “WHITE MATTER”
•“GRAY MATTER” IS MAINLY
COMPRISED OF GROUPS OF

10. CLASSIFICATION OF NEURONS
• STRUCTURAL CLASSIFICATION BASED ON NUMBER OF PROCESSES COMING OFF
OF THE CELL BODY:

11. • ANAXONIC NEURONS
• NO ANATOMICAL CLUES TO DETERMINE
AXONS FROM DENDRITES
• FUNCTIONS UNKNOWN

12. • BIPOLAR NEURON
• TWO PROCESSES COMING OFF
CELL BODY – ONE DENDRITE &
ONE AXON
• ONLY FOUND IN EYE, EAR & NOSE

13. • UNIPOLAR (PSEUDOUNIPOLAR)
NEURON
• SINGLE PROCESS COMING OFF
CELL BODY, GIVING RISE TO
DENDRITES (AT ONE END) & AXON
(MAKING UP REST OF PROCESS)

14. • MULTIPOLAR NEURON
• MULTIPLE DENDRITES & SINGLE
AXON
• MOST COMMON TYPE

15. CLASSIFICATION OF NEURONS
• FUNCTIONAL CLASSIFICATION BASED ON TYPE OF INFORMATION & DIRECTION OF
INFORMATION TRANSMISSION:
• SENSORY (AFFERENT) NEURONS –
• TRANSMIT SENSORY INFORMATION FROM RECEPTORS OF PNS TOWARDS THE CNS
• MOST SENSORY NEURONS ARE UNIPOLAR, A FEW ARE BIPOLAR
• MOTOR (EFFERENT) NEURONS –
• TRANSMIT MOTOR INFORMATION FROM THE CNS TO EFFECTORS (MUSCLES/GLANDS/ADIPOSE
TISSUE) IN THE PERIPHERY OF THE BODY
• ALL ARE MULTIPOLAR
• ASSOCIATION (INTERNEURONS) –
• TRANSMIT INFORMATION BETWEEN NEURONS WITHIN THE CNS; ANALYZE INPUTS, COORDINATE
OUTPUTS
• ARE THE MOST COMMON TYPE OF NEURON (20 BILLION)
• ARE ALL MULTIPOLAR

17. CENTRAL NERVOUS SYSTEM (CNS)
 THE HUMAN CENTRAL NERVOUS SYSTEM IS MADE UP OF;
 1. BRAIN
 2. SPINAL CORD
 THE COMPLETE CENTRAL NERVOUS SYSTEM CONSIST OF UP TO 100 BILLIONS INTER-NEURONS
 BRAIN AND SPINAL CORD ARE PROTECTED IN PROTECTED BONY ARMOUR, THE
SKULL AND THE VERTEBRAL COLUMN.
 BOTH THE SPINAL CORD AND BRAIN ARE COVERED IN THREE CONTINUOUS SHEETS
OF CONNECTIVE TISSUE CALLED MENINGES.
 A PLASMA LIKE FLUID, THE CEREBROSPINAL FLUID (CSF) BATHING THE NEURONS
OF CNS IS YET ANOTHER PROTECTION TO CNS.

18. BRAIN
• THE BRAIN OF ALL VERTEBRATES
DEVELOPS FROM THREE SWELLINGS AT
THE ANTERIOR END OF THE NEURAL
CANAL OF THE EMBRYO.
• HUMAN BRAIN IS DIVIDED INTO THREE
PARTS:
 FORE-BRAIN
 MID-BRAIN
 HIND-BRAIN

19. FORE-BRAIN
• THE HUMAN FOREBRAIN IS MADE UP
OF;
• TELENCEPHALON
• DIENCEPHALON
• THE TELENCEPHALON IS THE LARGEST
PART OF FORE-BRAIN IT IS
DIFFERENTIATED INTO TWO
CEREBRAL HEMISPHERE OR
CEREBRUM.

20. FORE-BRAIN
• CEREBRAL CORTEX IS THE LARGEST AND MOST COMPLEX PART OF HUMAN
BRAIN.
• BY MEANS OF A PROMINENT GROOVE, CALLED THE LONGITUDINAL FISSURE, THE
BRAIN IS DIVIDED INTO TWO HALVES CALLED CEREBRAL HEMISPHERES.
• AT THE BASE OF THIS FISSURE LIES A THICK BUNDLE OF NERVE FIBERS, CALLED
THE CORPUS CALLOSUM, WHICH PROVIDES A COMMUNICATION LINK BETWEEN
THE HEMISPHERES ALTHOUGH THE RIGHT AND LEFT HEMISPHERES SEEM TO BE A
MIRROR IMAGE OF ONE ANOTHER, THERE ARE IMPORTANT FUNCTIONAL
DISTINCTIONS.
• EACH HEMISPHERE OF THE CEREBRUM IS SUBDIVIDED INTO FOUR LOBES.

21. FORE-BRAIN
• FRONTAL LOBE- ASSOCIATED WITH REASONING, PLANNING, PARTS OF SPEECH,
MOVEMENT, EMOTIONS, AND PROBLEM SOLVING.
• PARIETAL LOBE- ASSOCIATED WITH MOVEMENT, ORIENTATION, RECOGNITION,
PERCEPTION OF STIMULI.
• OCCIPITAL LOBE- ASSOCIATED WITH VISUAL PROCESSING.
• TEMPORAL LOBE- ASSOCIATED WITH PERCEPTION AND RECOGNITION OF
AUDITORY STIMULI, MEMORY, AND SPEECH.

22. MID-BRAIN
• THE MIDBRAIN IS LOCATED BETWEEN THE
TWO DEVELOPMENTAL REGIONS OF THE
BRAIN KNOWN AS THE FOREBRAIN AND
HIND BRAIN.
• IN MAMMALS, PARTICULARLY IN MAN, MID
BRAIN IS RELATIVELY VERY SMALL. WITHIN
THE MIDBRAIN IS THE RETICULAR
FORMATION, WHICH IS PART OF A CERTAIN
REGION OF THE BRAINSTEM THAT
INFLUENCES MOTOR FUNCTIONS.
• IT RECEIVES THE SENSORY INFORMATION
FROM SPINAL CORD AND SENDS THEM TO
THE FORE-BRAIN.

23. HIND-BRAIN
• CEREBELLUM:
THE CEREBELLUM, OR "LITTLE BRAIN", IS
SIMILAR TO THE CEREBRUM IN THAT IT
HAS TWO HEMISPHERES AND HAS A
HIGHLY FOLDED SURFACE OR CORTEX.
THIS STRUCTURE IS ASSOCIATED WITH
REGULATION AND COORDINATION OF
MOVEMENT, POSTURE, AND BALANCE.

24. HIND-BRAIN
• PONS : IS A STRUCTURE LOCATED ON THE BRAIN STEM. IT IS SUPERIOR TO (UP
FROM) MEDULLA OBLONGATA, INFERIOR TO (DOWN FROM) THE MIDBRAIN AND
VENTRAL TO (IN FRONT OF) THE CEREBELLUM. THE PONS MEASURES ABOUT 2.5
CM IN LENGTH. IT MAINLY CONTROLS WITH SLEEP, RESPIRATION, SWALLOWING,
BLADDER CONTROL, HEARING, EQUILIBRIUM, TASTE, EYE MOVEMENT, FACIAL
EXPRESSIONS, FACIAL SENSATION, AND POSTURE.
• RETICULAR FORMATION : IS A GROUP OF NERVE FIBERS LOCATED INSIDE THE
BRAINSTEM. RETICULAR FORMATION IMPORTANT IN REGULATING AROUSAL,
ATTENTION, CARDIAC REFLEXES, MOTOR FUNCTIONS, CONSCIOUSNESS OR
WAKEFULNESS.

25. HIND-BRAIN
• MEDULLA OBLONGATA:
• MEDULLA OBLONGATA ALSO CALLED THE
MESENCEPHALON, THE LOWEST PART OF
THE BRAINSTEM. THE MEDULLA OBLONGATA
LOOKS LIKE A SWELLING AT THE TIP OF THE
SPINAL CORD.
• THE MEDULLA OBLONGATA REGULATES THE
REFLEX RESPONSES THAT CONTROL
BREATHING, HEART BEAT, BLOOD PRESSURE,
COUGHING, SWALLOWING, HICCUPPING,
SNEEZING, VOMITING, DIGESTION AND
OTHER ESSENTIAL INVOLUNTARY
FUNCTIONS.

26. BRAIN-STEM
• THE LOWER EXTENSION OF THE BRAIN WHERE IT CONNECTS TO THE SPINAL
CORD. IT IS FORMED BY THE COMBINATION OF MEDULLA OBLONGATA, PONS
AND MID–BRAIN. NEUROLOGICAL FUNCTIONS LOCATED IN THE BRAINSTEM
INCLUDE THOSE NECESSARY FOR SURVIVAL (BREATHING, DIGESTION, HEART
RATE, BLOOD PRESSURE) AND FOR AROUSAL (BEING AWAKE AND ALERT). THE
BRAINSTEM IS THE PATHWAY FOR ALL FIBER TRACTS PASSING UP AND DOWN
FROM PERIPHERAL NERVES AND SPINAL CORD TO THE HIGHEST PARTS OF THE
BRAIN.

27. SPINAL CORD
• IT IS THICK, WHITISH NERVE CORD THAT
LIES BELOW THE MEDULLA AND EXTENDS
DOWN THROUGH THE NEURAL CANAL OF
VERTEBRAE UP TO THE HIPS.
• THE SPINAL CORD EXTENDS DOWN FROM
THE BRAIN STEM AT THE BASE OF THE
SKULL, ENCLOSED IN THE VERTEBRAL
COLUMN. BRAIN AND SPINAL CORD IN
CONTINUITY COMPRISE THE CENTRAL
NERVOUS SYSTEM.
• THE OUTER LAYER OF THE SPINAL CORD
CONSISTS OF WHITE MATTER, I.E., MYELIN-SHEATHED
NERVE FIBERS. THESE ARE
BUNDLED INTO SPECIALIZED TRACTS THAT
CONDUCT IMPULSES TRIGGERED BY
PRESSURE, PAIN, HEAT, AND OTHER
SENSORY STIMULI OR CONDUCT MOTOR
IMPULSES ACTIVATING MUSCLES AND

28. CONDUCTION THROUGH SPINAL CORD

29. PERIPHERAL NERVOUS SYSTEM (PNS)
 IN MAN, THE PERIPHERAL NERVOUS SYSTEM CONSISTS OF
• 12 PAIRS OF CRANIAL NERVES
• 31 PAIRS OF SPINAL NERVES
 THE PNS TRANSMITS SIGNALS BETWEEN CNS AND REST OF THE BODY.
 PNS IS FURTHER DIVIDED INTO
• SOMATIC NERVOUS SYSTEM(VOLUNTARY)
• AUTONOMIC NERVOUS SYSTEM(INVOLUNTARY)

31. AUTONOMIC NERVOUS SYSTEM
 AUTONOMIC NERVOUS SYSTEM IS THE DIVISION OF THE PERIPHERAL NERVOUS
SYSTEM THAT CONTROLS THE GLANDS AND THE MUSCLES OF THE INTERNAL
ORGANS.
 THE AUTONOMIC NERVOUS SYSTEM OPERATES ON ITS OWN AND IS
INVOLUNTARY.
 THE TWO DIVISIONS OF AUTONOMIC NERVOUS SYSTEM ARE
 SYMPATHETIC NERVOUS SYSTEM
 PARASYMPATHETIC NERVOUS SYSTEM

32. COMPARISON
• IT IS FORMED BY THE SPINAL NERVES
ARISING FROM THORACIC AND LUMBAR
REGION.
• IT PREPARES THE BODY FOR HIGHLY
ENERGETIC ACTIVITY SUCH AS FIGHT
OR FLIGHT.
• IT IS RESPONSIBLE FOR
• DILATED PUPIL
• ACCELERATED HEARTBEAT
• SLOWER DIGESTION
• STIMULATED GLUCOSE RELEASE
• ACCELERATED BREATHING RATE
PARASYMPATHETIC
NERVOUS SYSTEM
• IT IS FORMED BY VAGUE NERVE, SOME
OF THE CRANIAL NERVES AND SPINAL
NERVES ARISING FROM SACRAL REGION.
• IT PROMOTES ALL THE INTERNAL
RESPONSES ASSOCIATED WITH A
RELAXED STATE.
• IT IS RESPONSIBLE FOR
• CONTRACTED PUPIL
• SLOWER HEARTBEAT
• STIMULATED DIGESTION
SYMPATHETIC
NERVOUS SYSTEM