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,

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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