BIOMEDICAL INSTRUMENTSSUBMITTED BY:

DIVYA SHARMA (110170117007)

HARSHITA SHAH (110170117023)

SUBMITTED TO:

PROF. R.K. SHUKLA

(ASSISTANT PROFESSOR)

TOPIC: “NERVOUS SYSTEM”

CONTENT

ORGANIZATION OF THE NERVOUS SYSTEM

THE NEURON

CENTRAL NERVOUS SYSTEM

PERIPHERAL NERVOUS SYSTEM

AUTONOMIC NERVOUS SYSTEM

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

GENERAL ORGANIZATION OF THE NERVOUS SYSTEM

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

NEUROGLIA (GLIAL CELLS)

• CNS NEUROGLIA:

• ASTROCYTES

• OLIGODENDROCYTES

• MICROGLIA

• EPENDYMAL CELLS

• PNS NEUROGLIA:

• SCHWANN CELLS (NEUROLEMMOCYTES)

• SATELLITE CELLS

NEURON STRUCTURE

•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

NEURON CELL BODIES, DENDRITES

CLASSIFICATION OF NEURONS• STRUCTURAL CLASSIFICATION BASED ON NUMBER OF PROCESSES COMING OFF

OF THE CELL BODY:

• ANAXONIC NEURONS

• NO ANATOMICAL CLUES TO DETERMINE

AXONS FROM DENDRITES

• FUNCTIONS UNKNOWN

• BIPOLAR NEURON

• TWO PROCESSES COMING OFF

CELL BODY – ONE DENDRITE &

ONE AXON

• ONLY FOUND IN EYE, EAR & NOSE

• UNIPOLAR (PSEUDOUNIPOLAR)

NEURON

• SINGLE PROCESS COMING OFF

CELL BODY, GIVING RISE TO

DENDRITES (AT ONE END) & AXON

(MAKING UP REST OF PROCESS)

• MULTIPOLAR NEURON

• MULTIPLE DENDRITES & SINGLE

AXON

• MOST COMMON TYPE

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

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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 GLANDS.

CONDUCTION THROUGH SPINAL CORD

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)

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

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