ppt introduction to nervous system by dr.qazi imtiaz rasool h.o.d. gmc srinagar kashmir
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ppt introduction of nervous system by qaziTRANSCRIPT
INTRODUCTION OF NERVOUS SYSTEM
BY QAZI IMTIAZ RASOOL H.O.D GMC
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What are we doing with ourbrains at this moment?
Don’t get nervous about NERVOUS SYSTEM
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The student’s brain;
Feeling your chair Squirming (moving) ,Watching ,Listening, Remembering ,Paying
Attention, Sleeping
Feeling anxious Feeling hungry
What happens when you ask a question?
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MAINTENANCE AND PROTECTION OF THE CNS
1. Glial Cells: physical and metabolic support
2. Skull and Spinal Column
3. Cerebrospinal fluid
4. Blood-brain barrier
5. Blood supply
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Skull and Spinal Column
1. PROVIDE MECHANICAL SUPPORT
2. PROTECTS THE NEURAL AND
SUPPORTING TISSUE
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CEREBROSPINAL FLUID
1. SHOCK ABSORBER
2. DENSITY IS THE SAME AS BRAIN
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Blood-brain barrier
1. LIMITS ACCESS OF BLOOD MATERIALS TO
BRAIN TISSUE
2. PROTECTS BRAIN FROM FLUCTUATIONS IN
BLOOD LEVELS
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INTRODUCTION TONERVOUS SYSTEM
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Primary Tissues4 Different Primary Tissues:
Muscle Nervous Epithelial
Connective
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11 Systems
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Homeostasis1. Maintaining constancy of internal environment.
Body temp ; urine vol ; gas vol ;Circulation, movement
2.Dynamic consistency. Sensory device, sight, hearing, taste, pain
2. Maintained by feedback loops.
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Basic physiological Functions of the Nervous SystemSensation
Monitors changes/events occurring in and outside the body. Such changes are known as stimuli and the cells that monitor them are receptors.
IntegrationThe parallel processing and interpretation of
sensory information to determine the appropriate response
ReactionMotor output.
The activation of muscles or glands (typically via the release of neurotransmitters (NTs))
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.
1. Electrical properties of the neuron2. Signal transmission3. Action potential4. Events at the synapse5. Electrical synapses6. Ionic environments of the neurons7. Chemical messengers of the neurons
a. Neurotransmittersb. Neuromodulators
c. Neuropeptidesd. Neurohormones
Basic Principles of NS Function at molecular level
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NUMBER
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History of Neurobiology
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Luigi Galvani.
(1737-1798 AD)
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Cell theory
Schlieden +Schwann-1839
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Camillo Golgi
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Reymonds-1896
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Waldeyer
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Evolution
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ARBORAZATION
Is Handedness Inherited?human bias for right-handedness has been
around a long time and is pervasivestudies of prehistoric cave drawings, tools, and
arm/hand bones (Corballis, 1989; Steele, 2000)right-handedness prevalent in all human
cultures before effects of culture: more than 9 of 10 fetuses
suck the right hand’s thumb in the womb (Hepper et al., 1990, 2004)
chimpanzees and gorillas (closely related to humans) = 65% right-handed (Hopkins et al., 2005)other, more distant primates are more evenly
split
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SPECIAL FEATURES OF NERVOUS SYSTEM
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BASIC FUNCTIONAL UNIT
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Nervous TissueHighly cellular
2 cell typesNeurons
Functional, signal conducting cellsNeuroglia
Supporting cells
1.
2.
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1.COMPARISION
WITH COMPUTORS
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COMPARISION WITH COMPUTORS1. INPUT
2. OUTPUT3. CENTRE
4. INTEGRATION5. SPEED
6. NEW IDEAS7. ENERGY
8. PROPER CONNECTIONS9. INSULATION
10.DAY DREAMING11.OUTPUT FLEXIBILITY
12.ORGINALITY
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Computers vs. Brains Processing elements: There are,108
transistors
R 10 synapses
1. Processing speed: 109 Hz
2. Intelligence and consciousness: the computer shows lack of intelligence.
3. Evolution: computers have been evolving for decades
1. Brain 100 Hz
2. The brain is highly intelligent andconscious.
3.The brains have been evolving for tens of millions of years,
14
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1. Fault tolerant: whereas the computer is not.
2. Adaptive: whereas the computer doesn’t evencompare with an infant’s learning capabilities.
3. Style of computation:
whereas the computer mostly serially and centralized
1. Fault tolerant: The brain is fault tolerant
2. Adaptive: The brain learns fast.
3. The brain computes in parallel and distributedmode,
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Neuroscience in the news
1.relatively recent2.interdispilanary 3.uses many levels of analysis Organisms
(behavior)SystemsCircuitsNeurons
Molecules
4. Neuro -genesis Growth of new neurons Once thought impossible
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. 1.Stem cells research , Immature cells that renew
themselves
and have the potential. to develop into
mature cells
2.Embryonic stem cells are most useful Controversial
3.In 2001, President U.S.A signed executive order
preventing creation of new cell
lines.
4.Some scientists want the ban lifted
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2.LACK OF LYMPHACITIC SYSTEM
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3. DEVELOPMENT
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4.Neural Induction1) Induction signals
1) From embryonic tissue2) Modulate gene expression
2) Retinoic acid1) Steroid hormone
3) Peptide hormones1) Fibroblast growth factor (FGF)2) Transforming growth factor (TGF)
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Neuronal structure develops in 4 major stages:
1. Proliferation,Neurogenesis
2. Migration
3. Differentiation
4. Synaptogenesis
5. .Development of the neuronal structure physiologically occurs in 8 stages
1. Mitosis/Proliferation
2. Migration(rate=6-10µm/min)
3. Differentiation
4. Aggregation
5. Synaptogenesis
6. Neuron Death
7. Synapse Rearrangement
8. Myelination
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Stages of Development
target identification
migration
neurogenesis
axonal extension
synaptogenesis
morphological differentiation
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6.Critical Periods in Human Development
1. Embryonic development (9 week)
2. Fetal development (until birth)
3. Postnatal development e.g. Critical
period for language acquisition
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7. MATURATION
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8. NEUROPLASICITY
1. Development2. Activity
3. Learning4. Habituation
5. Response to injury6. Rehabilitation
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9 stimulating environment increases dendritic branching and number of dendritic spines
Standard environment Enriched environment
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10 .DESTRUCTION
1..one-year old human has about 100 billion (1011)
neurons.
2. No new neurons will be formed after that age,? ?
?3.neurons will be lost at a rate of roughly 200,000
per day (a net loss of 2 to 5% by
age 50).
4.Maximum brain weight is achieved at about age
21
5.Hypothalamus is the last to deverlope
compeletly
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10. RMP= -65mV
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11.NUMBER OF THE CELLS
Guess what? There are more nerve cells in the human
brain than there are stars in the Milky Way.
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The Human Brain100 billion
1 billion In The Spinal Cord
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A single neuron on the surface of a microprocessor A cm3 of the brain will
contain >50 million neurons
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12.Number of neurons &connections in the cortex alone 12-15 billons+60 trillion
Number of neurons cerebellum= 70 billons
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11.DIFFERENT TYPES
50 MILLION DIFFERENT CELLS
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13. PRODUCTION
1/3 million per min in 9 months of gestation
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14.LOSS OF DIVIDING PROPERTIES
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15.Binary code Principle
-encode information at the cellular level.
Neurons encode information by the 1. Frequency modulation
2. On and Off mechanism of electrical impulses, controlled by chemical signal(NT) from other
cells.
FREQUENCY CODE
1.
2.
3.
Weak stimulus
Moderate stimulus
Strong stimulus
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16. BUOYANCY
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1. CSF is a watery “ broth”found in and around
the brain and spinal cord
2. It forms a liquid cushion that gives buoyancy
to the CNS organs
3. With the brain floating, CSF reduces brain
weight by 97% and thus prevents the brain
from crushing under its own weight
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17. ASYMMETRICAL FUNCTIONING IN THE BRAIN
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18.SEX DIFFERENCE IN LATERALISATION OF LANGUAGE
1. MALES ------LEFT HEMISPHERE ACTIVATION ONLY
2. FEMALES SHOW LEFT & RIGHT
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19.Sexual Dimorphism In Grey Matter Thickness(MRI)
1. Note women have more grey matter on
the right(0.45 mm thicker)
2. inferior parietal and
3. posterior temporal areas
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20 .LENGTH OF NERVOUS SYSTEM
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LENGTH OF THE CELL IN THIS SYSTEM (NEURON)
AXON
0.1 - 1,000 mm length thin, uniform width
SOMA
DEN
DR
ITES
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21.Longest cell1. blue whale neuron
1. 10-30 meters
2. giraffe axon1. 5 meters
3. human neuron1. 1-2 meters
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one neuron is about 10 microns long. Remember, this is just an example, because neurons come in all different sizes. So, if we line up 100 billion neurons which are 10 microns long . . .
100,000,000,000 neurons x 10 microns= 1000 km or about 600 miles!
This may help with the math:1000 microns= 1milimeter (mm)
10 mm= 1centimeter (cm)100 cm= 1 meter (m)
1000 m= 1 kilometer (km)
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22. 40% PARTCIPATION OF GENEtissue-specific gene expression.
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23.AMOUNT OF mRNA PRODUCTION
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24.NKP
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25.B.M.R
1. 7.5 TIMES THAN THE NON- NERVOUS TISSUES
2. Children have twice the metabolic rate/ unit vol. than the adults
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26.1.Weight 2-3% of body
2.O2 Consumption20% of total
3.Brain Energy (Glucose) Utilization20% of total
4.Brain Blood Flow20% of heart output at rest
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27. FASTEST RESPONSE
Nervous system allows for 1 millisecond response time
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28.HOMOESTSIS
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Nervous vs. Endocrine System
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Hypothalamus Autonomic nervous system NeuroendocrineBrain stem andspinal cord Pituitary
Maintain body homeostasis
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METHODS OF NEUROPHYSIOLOGYSTUDIES
1. Microscopic
a. Light microscopy b. TEM , SEM and freeze fracture
C) Sharp metal and glass-filled electrodes plus suction electrodes for patch clamp technique
2. Cathode Ray Oscilloscope3. Stains (1) Methylene blue (2) Cobalt filling (3) Fluorescent-Lucifer yellow and dextran-rhodamine (4) Immunological stains (fluorescent antibodies)
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4.Histological Analyses
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5.Computed tomography (CAT)
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6.Magnetic Resonance Imaging (MRI)Use electromagnetic fields to image
atom (hydrogen) densityScan living brain Protons (H+) respond to magnetic fieldHigh resolutionExpensive
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7.Functional MRI
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8.CLINICAL PHYSIOLOGY
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9.Positron Emission Tomography (PET)
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Optical Imaging & TMS
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10.Electroencephalogram (EEG)
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11. Behavioral Neuroscience: Animal Experimentation
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EFFCTS OF AGE(BRAIN)1.Enlargement of the volume of the ventricles:
because cells surrounding the ventricles are lost2. Widening of sulci (the grooves) on the surface of the
brain3. Reduced brain weight and brain volume: caused by the loss of neurons.4. Loss of NT5. Neurological disorders: brain disorders
Alzheimer’s disease,Parkinson's disease
and stroke
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EFFCTS OF AGE CORD +NERVES
1. Myelin sheath increases- 1st sensory in foetal
life than motor after birth
2. Axon increases in length
3. Arborization increases
4. Synaptic connections increases
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1. Glial tissue increases
2. Neuronal size increases
11.Loss of neurones 40% with age more in males than females
04/10/2023 91HOMUNCULUS
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Definition of death1. Traditionally Doctor Declare A Person Dead When
His Heart & Respiration Stops
2. Recent Times Both The Things Can Be Maintained Artifiically For Longer Times
3. For Organ Transplant And Resumption An EEG Silence R Brain Death Is An Accepted Creteria If The Subject Should Be In Coma And Apnoea For 6 Hours Following Which EEG Silence Is Present Continously For At Least 30 Minutes.
4. No Legal Definition
5. EEG Silence Is Defined As Absence Of Electrical Potential Over 2mv. From Symmetrical Placed Electrodes Pairs Over 10 Cms . Apart With An Inter Electrode Resistance Between 100-1000 Ohms.
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Development Aspects of the Nervous System
· The nervous system is formed during the first month of embryonic development
· Any maternal infection can have extremely harmful effects
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SUMMARYInteresting Facts
1 A newborn baby's brain grows almost 3 times during the course of its first year.
2. Your brain is made mostly of water. (85%)3. A New born baby loses about half of their nerve cells
before they are born.4. As we get older, the brain loses almost one gram / year.5. The total surface area of the human brain is about
25, 000 square cm.6. The base of the spinal cord has a cluster of nerves, which are most sensitive.
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7. An average adult male brain weighs about
1375 grams.
8. An average adult female brain is about 1275
grams.
9. 4% percent of the brain's cells work while the
remaining cells are kept in reserve.
10.Gray matter 3 time > white matter
11.No O2 reserve
– loss of consciousness in 10 seconds
– irreversible damage in 3-5 minutes
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• SOME RECENT FACTS ABOUT NERVOUS SYTEM
1. Precursor cells can give birth to new neurons when
immersed in a growth-promotion protein
2. Physical and mental exercise promote the survival
and the production of new precursor cells
3. Stress can prohibit the production of new cells
4. Nicotine can kill precursor cells