INTRODUCTION TO NERVOUS SYSTEM BY DR QAZI IMTIAZ H.O.D.author stream 1

What are we doing with our brains at this moment? :

What are we doing with our brains at this moment? Don’t get nervous about NERVOUS SYSTEM 4/10/2011 1

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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? 4/10/2011 2

MAINTENANCE AND PROTECTION OF THE CNS:

MAINTENANCE AND PROTECTION OF THE CNS Glial Cells: physical and metabolic support Skull and Spinal Column Cerebrospinal fluid Blood-brain barrier Blood supply 4/10/2011 3

Skull and Spinal Column:

Skull and Spinal Column PROVIDE MECHANICAL SUPPORT PROTECTS THE NEURAL AND SUPPORTING TISSUE 4/10/2011 4

CEREBROSPINAL FLUID:

CEREBROSPINAL FLUID SHOCK ABSORBER DENSITY IS THE SAME AS BRAIN 4/10/2011 5

Blood-brain barrier:

Blood-brain barrier LIMITS ACCESS OF BLOOD MATERIALS TO BRAIN TISSUE PROTECTS BRAIN FROM FLUCTUATIONS IN BLOOD LEVELS 4/10/2011 6

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INTRODUCTION TO NERVOUS SYSTEM 4/10/2011 7

Primary Tissues 4 Different Primary Tissues: Muscle Nervous Epithelial Connective :

4/10/2011 8 Primary Tissues 4 Different Primary Tissues: Muscle Nervous Epithelial Connective

11 Systems:

11 Systems 4/10/2011 9

Homeostasis:

Homeostasis Maintaining constancy of internal environment. Body temp ; urine vol ; gas vol ; Circulation, movement 2.Dynamic consistency. Sensory device, sight, hearing, taste, pain Maintained by feedback loops. 4/10/2011 10

Basic physiological Functions of the Nervous System :

Basic physiological Functions of the Nervous System Sensation Monitors changes/events occurring in and outside the body. Such changes are known as stimuli and the cells that monitor them are receptors. Integration The parallel processing and interpretation of sensory information to determine the appropriate response Reaction Motor output. The activation of muscles or glands (typically via the release of neurotransmitters (NTs)) 4/10/2011 11

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. 1. Electrical properties of the neuron 2. Signal transmission 3. Action potential 4. Events at the synapse 5. Electrical synapses 6. Ionic environments of the neurons 7. Chemical messengers of the neurons a. Neurotransmitters b. Neuromodulators c. Neuropeptides d. Neurohormones 4/10/2011 12 Basic Principles of NS Function at molecular level

NUMBER:

NUMBER 4/10/2011 13

History of Neurobiology:

History of Neurobiology 4/10/2011 14

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4/10/2011 16 Luigi Galvani . (1737-1798 AD)

Cell theory:

Cell theory Schlieden +Schwann-1839 4/10/2011 17

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4/10/2011 18 Camillo Golgi

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Reymonds-1896 4/10/2011 19

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Waldeyer 4/10/2011 20

Evolution:

Evolution 4/10/2011 21

ARBORAZATION:

ARBORAZATION 4/10/2011 22

Is Handedness Inherited?:

Is Handedness Inherited? human bias for right-handedness has been around a long time and is pervasive studies 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

SPECIAL FEATURES OF NERVOUS SYSTEM:

SPECIAL FEATURES OF NERVOUS SYSTEM 4/10/2011 24

BASIC FUNCTIONAL UNIT:

BASIC FUNCTIONAL UNIT 4/10/2011 25

Nervous Tissue:

Nervous Tissue Highly cellular 2 cell types Neurons Functional, signal conducting cells Neuroglia Supporting cells 4/10/2011 26 1. 2.

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1 .COMPARISION WITH COMPUTORS 4/10/2011 27

COMPARISION WITH COMPUTORS:

COMPARISION WITH COMPUTORS INPUT OUTPUT CENTRE INTEGRATION SPEED NEW IDEAS ENERGY PROPER CONNECTIONS INSULATION DAY DREAMING OUTPUT FLEXIBILITY ORGINALITY 4/10/2011 28

Computers vs. Brains:

Computers vs. Brains Processing elements: There are,108 transistors R 10 synapses Processing speed: 109 Hz Intelligence and consciousness: the computer shows lack of intelligence. Evolution: computers have been evolving for decade s Brain 100 Hz 2. The brain is highly intelligent and conscious. 3.The brains have been evolving for tens of millions of years, 4/10/2011 29 14

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Fault tolerant: whereas the computer is not. Adaptive: whereas the computer doesn’t even compare with an infant’s learning capabilities. 3. Style of computation: whereas the computer mostly serially and centralized Fault tolerant: The brain is fault tolerant Adaptive: The brain learns fast. The brain computes in parallel and distributed mode, 4/10/2011 30

Neuroscience in the news :

Neuroscience in the news 1.relatively recent 2.interdispilanary 3.uses many levels of analysis Organisms (behavior) Systems Circuits Neurons Molecules 4. Neuro -genesis Growth of new neurons Once thought impossible 4/10/2011 31

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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 4/10/2011 32

2.LACK OF LYMPHACITIC SYSTEM:

2. LACK OF LYMPHACITIC SYSTEM 4/10/2011 33

3. DEVELOPMENT:

3. DEVELOPMENT 4/10/2011 34

4.Neural Induction:

4. Neural Induction Induction signals From embryonic tissue Modulate gene expression Retinoic acid Steroid hormone Peptide hormones Fibroblast growth factor (FGF) Transforming growth factor (TGF) 4/10/2011 35

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Neuronal structure develops in 4 major stages: Proliferation,N eurogenesis Migration Differentiation Synaptogenesis 4/10/2011 36

5. .Development of the neuronal structure physiologically occurs in 8 stages :

5. .Development of the neuronal structure physiologically occurs in 8 stages Mitosis/Proliferation Migration(rate=6-10µm/min) Differentiation Aggregation Synaptogenesis Neuron Death Synapse Rearrangement Myelination

Stages of Development :

Stages of Development 4/10/2011 38 target identification migration neurogenesis axonal extension synaptogenesis morphological differentiation

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6 .Critical Periods in Human Development Embryonic development (9 week) Fetal development (until birth) Postnatal development e.g. Critical period for language acquisition 4/10/2011 39

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7. MATURATION 4/10/2011 42

8. NEUROPLASICITY:

8. NEUROPLASICITY Development Activity Learning Habituation Response to injury Rehabilitation 4/10/2011 43

9 stimulating environment increases dendritic branching and number of dendritic spines:

9 stimulating environment increases dendritic branching and number of dendritic spines 4/10/2011 44 Standard environment Enriched environment

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4/10/2011 46 10 .DESTRUCTION 1..one-year old human has about 100 billion (10 11 ) 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

10. RMP= -65mV:

10. RMP= -65mV 47

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4/10/2011 48 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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4/10/2011 49 The Human Brain 100 billion 1 billion In The Spinal Cord

A single neuron on the surface of a microprocessor A cm3 of the brain will contain >50 million neurons:

A single neuron on the surface of a microprocessor A cm3 of the brain will contain >50 million neurons 4/10/2011 50

12.Number of neurons &connections in the cortex alone 12-15 billons+60 trillion :

12 .Number of neurons &connections in the cortex alone 12-15 billons+60 trillion Number of neurons cerebellum= 70 billons 4/10/2011 51

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4/10/2011 52 11 . DIFFERENT TYPES 50 MILLION DIFFERENT CELLS

13. PRODUCTION 1/3 million per min in 9 months of gestation :

13 . PRODUCTION 1/3 million per min in 9 months of gestation 4/10/2011 53

14.LOSS OF DIVIDING PROPERTIES :

14 .LOSS OF DIVIDING PROPERTIES 4/10/2011 54

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15.Binary code Principle:

15 . Binary code Principle -encode information at the cellular level. Neurons encode information by the Frequency modulation On and Off mechanism of electrical impulses, controlled by chemical signal(NT) from other cells . 4/10/2011 56

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FREQUENCY CODE 1. 2. 3. Weak stimulus Moderate stimulus Strong stimulus

16. BUOYANCY:

16 . BUOYANCY 4/10/2011 58

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CSF is a watery “ broth”found in and around the brain and spinal cord It forms a liquid cushion that gives buoyancy to the CNS organs With the brain floating, CSF reduces brain weight by 97% and thus prevents the brain from crushing under its own weight 4/10/2011 59

17. ASYMMETRICAL FUNCTIONING IN THE BRAIN:

17 . ASYMMETRICAL FUNCTIONING IN THE BRAIN 4/10/2011 60

18.SEX DIFFERENCE IN LATERALISATION OF LANGUAGE:

18 .SEX DIFFERENCE IN LATERALISATION OF LANGUAGE 1. MALES ------LEFT HEMISPHERE ACTIVATION ONLY 2. FEMALES SHOW LEFT & RIGHT 4/10/2011 61

19.Sexual Dimorphism In Grey Matter Thickness (MRI) :

19. Sexual Dimorphism In Grey Matter Thickness (MRI) Note women have more grey matter on the right(0.45 mm thicker) inferior parietal and posterior temporal areas 4/10/2011 62

20 .LENGTH OF NERVOUS SYSTEM:

20 .LENGTH OF NERVOUS SYSTEM 4/10/2011 63

LENGTH OF THE CELL IN THIS SYSTEM (NEURON):

LENGTH OF THE CELL IN THIS SYSTEM (NEURON) 4/10/2011 64 AXON 0.1 - 1,000 mm length thin, uniform width SOMA DENDRITES

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21 .Longest cell blue whale neuron 10-30 meters giraffe axon 5 meters human neuron 1-2 meters 4/10/2011 65

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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) 4/10/2011 66

22. 40% PARTCIPATION OF GENE tissue-specific gene expression.:

22 . 40% PARTCIPATION OF GENE tissue-specific gene expression . 4/10/2011 67

23.AMOUNT OF mRNA PRODUCTION:

23. AMOUNT OF mRNA PRODUCTION 4/10/2011 68

24.NKP:

24 .NKP 4/10/2011 69

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 :

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 4/10/2011 70

26.1.Weight 2-3% of body 2.O2 Consumption 20% of total 3.Brain Energy (Glucose) Utilization 20% of total 4.Brain Blood Flow 20% of heart output at rest:

4/10/2011 71 26.1. Weight 2-3% of body 2. O 2 Consumption 20% of total 3. Brain Energy (Glucose) Utilization 20% of total 4. Brain Blood Flow 20% of heart output at rest

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4/10/2011 72 27. FASTEST RESPONSE Nervous system allows for 1 millisecond response time

28.HOMOESTSIS:

28. HOMOESTSIS 4/10/2011 73

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Nervous vs. Endocrine System:

Nervous vs. Endocrine System 4/10/2011 75

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Hypothalamus Autonomic nervous system Neuroendocrine Brain stem and spinal cord Pituitary Maintain body homeostasis 4/10/2011 76

METHODS OF NEUROPHYSIOLOGY STUDIES:

METHODS OF NEUROPHYSIOLOGY STUDIES 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 Oscilloscope 3. Stains (1) Methylene blue (2) Cobalt filling (3) Fluorescent-Lucifer yellow and dextran-rhodamine (4) Immunological stains (fluorescent antibodies) 77

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4/10/2011 78 4.Histological Analyses

5.Computed tomography (CAT) :

5.Computed tomography (CAT) 4/10/2011 79

6.Magnetic Resonance Imaging (MRI):

6.Magnetic Resonance Imaging (MRI) 4/10/2011 80 Use electromagnetic fields to image atom (hydrogen) density Scan living brain Protons (H + ) respond to magnetic field High resolution Expensive

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4/10/2011 81 7.Functional MRI

8.CLINICAL PHYSIOLOGY:

8.CLINICAL PHYSIOLOGY 4/10/2011 82

9.Positron Emission Tomography (PET):

9.Positron Emission Tomography (PET) 4/10/2011 83

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4/10/2011 84 Optical Imaging & TMS

10.Electroencephalogram (EEG):

10.Electroencephalogram (EEG) 4/10/2011 85

11. Behavioral Neuroscience: Animal Experimentation:

11. Behavioral Neuroscience: Animal Experimentation 4/10/2011 86

EFFCTS OF AGE (BRAIN):

EFFCTS OF AGE (BRAIN) 1.Enlargement of the volume of the ventricles: because cells surrounding the ventricles are lost 2. Widening of sulci (the grooves) on the surface of the brain 3. Reduced brain weight and brain volume: caused by the loss of neurons. 4. Loss of NT 5. Neurological disorders: brain disorders Alzheimer’s disease, Parkinson's disease and stroke 4/10/2011 87

EFFCTS OF AGE CORD +NERVES:

EFFCTS OF AGE CORD +NERVES 4/10/2011 88 Myelin sheath increases- 1 st sensory in foetal life than motor after birth Axon increases in length Arborization increases Synaptic connections increases

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Glial tissue increases Neuronal size increases 11.Loss of neurones 40% with age more in males than females 4/10/2011 89

HOMUNCULUS:

4/10/2011 90 HOMUNCULUS

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Definition of death:

Definition of death Traditionally Doctor Declare A Person Dead When His Heart & Respiration Stops Recent Times Both The Things Can Be Maintained Artifiically For Longer Times 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. No Legal Definition 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. 4/10/2011 92

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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 4/10/2011 93

SUMMARY Interesting Facts :

SUMMARY Interesting Facts 4/10/2011 94 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 g rams. 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 4/10/2011 95

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4/10/2011 96 SOME RECENT FACTS ABOUT NERVOUS SYTEM Precursor cells can give birth to new neurons when immersed in a growth-promotion protein Physical and mental exercise promote the survival and the production of new precursor cells Stress can prohibit the production of new cells Nicotine can kill precursor cells