ppt on cns

Central Nervous System (CNS)Central Nervous System (CNS)

BrainBrain Spinal CordSpinal Cord

Peripheral Nervous System (PNS)Peripheral Nervous System (PNS)

Sensory NeuronsSensory NeuronsMotor NeuronsMotor Neurons

Somatic Nervous System• voluntary movements via

skeletal muscles

Somatic Nervous System• voluntary movements via

skeletal muscles

Autonomic Nervous System• organs, smooth muscles

Autonomic Nervous System• organs, smooth muscles

Sympathetic- “Fight-or-Flight” responses

Sympathetic- “Fight-or-Flight” responses

Parasympathetic - maintenance

Parasympathetic - maintenance

The Nervous System

Nervous System Nervous System

1. CENTRAL NERVOUS SYSTEM

MR.ASHOK BISHNOIMR.ASHOK BISHNOIAssist., Professor ,JINRAssist., Professor ,JINR

• Astrocytes:-

• Abundant, star-shaped cells

• Brace neurons

• Form barrier between capillaries and neurons

• Control the chemical environment of the brain (CNS)

• Microglia

• Spider-like phagocytes

• Dispose of debris

• Ependymal cells

• Line cavities of the brain and spinal cord

• Circulate cerebrospinal fluid

• OligodendrocytesProduce myelin sheath around nerve fibers in the CNS

•The central nervous system (CNS) consists of the brain & spinal cord.

• The brainstem connects the brain to the spinal cord.

• Communication to the peripheral nervous system (PNS) is by way of the spinal cord

• The meninges• Membranes covering brain & spinal cord• Protect the CNSThree (3) layers of tissue:-

• Dura mater ( outer layer)• “Tough mother”• Venous sinuses

• Arachnoid mater ( middle layer)• “Spider mother”• Space contains cerebrospinal fluid (CSF)

• Pia mater ( inner layer)• “Little mother”• Encapsulates blood vessels

Subdural space

Space between dura and arachnoid mater.

Epidural space

Space superior to dura.

Subarachnoid space

Space between arachnoid & pia materFilled with CSF

Contains the blood vessels supplying brain.

10

Spinal cord

Spinal cord

Pia mater

Arachnoid mater

Dura mater

Dorsal root

Dorsal root

Spinal nerve

Epidural space

(a) (b)

Ventral root

Dorsal rootganglion

Thoracicvertebra

Spinalnerve

Dorsal rootganglion

Subarachnoidspace

Dorsal branch(dorsal ramus)

Ventral branch(ventral ramus)

Ventral root

Epiduralspace

Body ofvertebra

11

• There are four (4) ventricles• It is interconnected cavities within cerebral hemispheres and brain stem

• The ventricles are continuous with the central canal of the spinal cord

• They are filled with CSF

• The four (4) ventricles are:• Lateral ventricles (2)

• Known as the first and second ventricles

• Third ventricle (1)• Fourth ventricle (1)

• Interventricular foramen• Cerebral aqueduct

Lateral ventricle

Third ventricle

Fourth ventricle

(a)

Interventricularforamen

Cerebralaqueduct

To central canalof spinal cord

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Third ventricle

(b)

Cerebralaqueduct

To central canalof spinal cord

Fourthventricle

Lateralventricle

Interventricularforamen

• Secretion of CSF-by the choroid plexus

•About 0.5 ml /mt•About 20ml/hrs•About 500-720 ml/day

•Specific gravity is 1.005

•pH of CSF is -7.33

•It is clear ,colorless alkaline fluid present in Subarachnoid space, ventricles of brain ,Central canal of spinal cord.

•Completely surrounds the brain and spinal cord

Composition of CSF:-

•Water•Glucose•Protein•Nitrogen substance•Electrolyte eg. Na,K,Cal,Chloride etc.

•Cell (few)

Process of CSF•CSF secreted by choroid plexus with in the cerebral ventricles (rt & lt) by ultra- filtration o& active secretion.

•From Rt & Lt lateral ventricle

Foramina

•Third ventricle

Cerebral aqueduct

•Fourth ventricle

Foramina lushka & Foramina magendia

•Sub arachnoid space

•Absorbe in the sinus

Function of CSF:-

1.Support the brain & spinal cord

2.Protect the brain & spinal cord

3.Maintain pressure around structure

4.Keep brain & spinal cord moist

5.Conveys nutrition to brain & spinal cord

6.Remove waste product of brain & spinal cord

Regions of the BrainRegions of the Brain

• Cerebral hemispheres

• Diencephalon

• Brain stem

• Cerebellum

Cerebral Hemispheres (Cerebrum)Cerebral Hemispheres (Cerebrum)

Slide 7.28a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Paired (left and right) superior parts of the brain

• Include more than half of the brain mass

Figure 7.13a

Cerebral Hemispheres (Cerebrum)Cerebral Hemispheres (Cerebrum)

Slide 7.28b


• The surface is made of ridges (gyri) and grooves (sulci)

Figure 7.13a

Lobes of the CerebrumLobes of the Cerebrum

Slide 7.29a


• Fissures (deep grooves) divide the cerebrum into lobes

• Surface lobes of the cerebrum

• Frontal lobe

• Parietal lobe

• Occipital lobe

• Temporal lobe

Lobes of the CerebrumLobes of the Cerebrum

Slide 7.29b


Figure 7.15a

Specialized Areas of the CerebrumSpecialized Areas of the Cerebrum

Slide 7.30Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Somatic sensory area – receives impulses from the body’s sensory receptors

• Primary motor area – sends impulses to skeletal muscles

• Broca’s area – involved in our ability to speak

Sensory and Motor Areas of the Sensory and Motor Areas of the Cerebral CortexCerebral Cortex


Figure 7.14

Specialized Area of the CerebrumSpecialized Area of the Cerebrum

Slide 7.32a


• Cerebral areas involved in special senses

• Gustatory area (taste)

• Visual area

• Auditory area

• Olfactory area


Slide 7.32b


• Interpretation areas of the cerebrum

• Speech/language region

• Language comprehension region

• General interpretation area


Slide 7.32c


Figure 7.13c

Layers of the CerebrumLayers of the Cerebrum

Slide 7.33a


• Gray matter

• Outer layer

• Composed mostly of neuron cell bodies

Figure 7.13a


Slide 7.33b


• White matter

• Fiber tracts inside the gray matter

• Example: corpus callosum connects hemispheres

Figure 7.13a


Slide 7.33c


• Basal nuclei – internal islands of gray matter

• Regulates voluntary motor activities by modifying info sent to the motor cortex

• Problems = ie unable to control muscles, spastic, jerky

• Involved in Huntington’s and Parkinson’s Disease

Figure 7.13a

DiencephalonDiencephalon

Slide 7.34a


• Sits on top of the brain stem

• Enclosed by the cerebral heispheres

• Made of three parts

• Thalamus

• Hypothalamus

• Epithalamus

DiencephalonDiencephalon

Slide 7.34b


Figure 7.15

ThalamusThalamus


• Surrounds the third ventricle

• The relay station for sensory impulses

• Transfers impulses to the correct part of the cortex for localization and interpretation

HypothalamusHypothalamus

Slide 7.36a


• Under the thalamus

• Important autonomic nervous system center

• Helps regulate body temperature

• Controls water balance

• Regulates metabolism

HypothalamusHypothalamus

Slide 7.36b


• An important part of the limbic system (emotions)

• The pituitary gland is attached to the hypothalamus

EpithalamusEpithalamus


• Forms the roof of the third ventricle

• Houses the pineal body (an endocrine gland)

• Includes the choroid plexus – forms cerebrospinal fluid

Brain StemBrain Stem

Slide 7.38a


• Attaches to the spinal cord

• Parts of the brain stem

• Midbrain

• Pons

• Medulla oblongata

Brain StemBrain Stem

Slide 7.38b


Figure 7.15a

MidbrainMidbrain


• Mostly composed of tracts of nerve fibers

• Reflex centers for vision and hearing

• Cerebral aquaduct – 3rd-4th ventricles

PonsPons


• The bulging center part of the brain stem

• Mostly composed of fiber tracts

• Includes nuclei involved in the control of breathing

Medulla OblongataMedulla Oblongata


• The lowest part of the brain stem

• Merges into the spinal cord

• Includes important fiber tracts

• Contains important control centers• Heart rate control

• Blood pressure regulation

• Breathing

• Swallowing

• Vomiting

CerebellumCerebellum

Slide 7.43a


• Two hemispheres with convoluted surfaces

• Provides involuntary coordination of body movements

CerebellumCerebellum

Slide 7.43b


Figure 7.15a

Protection of the Central Nervous Protection of the Central Nervous SystemSystem

Slide 7.44a


• Scalp and skin

• Skull and vertebral column

• Meninges

Figure 7.16a

Protection of the Central Nervous Protection of the Central Nervous SystemSystem

Slide 7.44b


• Cerebrospinal fluid

• Blood brain barrier

Figure 7.16a

MeningesMeninges

Slide 7.45a


• Dura mater

• Double-layered external covering

• Periosteum – attached to surface of the skull

• Meningeal layer – outer covering of the brain

•Folds inward in several areas

MeningesMeninges

Slide 7.45b


• Arachnoid layer

• Middle layer

• Web-like

• Pia mater

• Internal layer

• Clings to the surface of the brain

Cerebrospinal FluidCerebrospinal Fluid


• Similar to blood plasma composition

• Formed by the choroid plexus

• Forms a watery cushion to protect the brain

• Circulated in arachnoid space, ventricles, and central canal of the spinal cord

Ventricles and Location of the Ventricles and Location of the Cerebrospinal FluidCerebrospinal Fluid

Slide 7.47a


Figure 7.17a

Ventricles and Location of the Ventricles and Location of the Cerebrospinal FluidCerebrospinal Fluid

Slide 7.47b


Figure 7.17b

Blood Brain BarrierBlood Brain Barrier


• Includes the least permeable capillaries of the body

• Excludes many potentially harmful substances

• Useless against some substances• Fats and fat soluble molecules• Respiratory gases• Alcohol• Nicotine• Anesthesia

Traumatic Brain Injuries (TBI)Traumatic Brain Injuries (TBI)


• Concussion• Slight or mild brain injury

• Bleeding & tearing of nerve fibers happened

• Recovery likely with some memory loss

• Contusion• A more severe TBI

• Nervous tissue destruction occurs

• Nervous tissue does not regenerate

• Cerebral edema• Swelling from the inflammatory response

• May compress and kill brain tissue

• Cerebral edema– Swelling from the inflammatory response

– May compress and kill brain tissue

• Subdural hematoma– Collection of blood below the dura

• Standards for these conditions were revised in 2004. Please check out TBIs at Mayoclinic.com for more current information on diagnostic terminology.

Cerebrovascular Accident (CVA)Cerebrovascular Accident (CVA)


• Commonly called a stroke

• The result of a ruptured blood vessel supplying a region of the brain

• Brain tissue supplied with oxygen from that blood source dies

• Loss of some functions or death may result

Alzheimer’s DiseaseAlzheimer’s Disease


• Progressive degenerative brain disease

• Mostly seen in the elderly, but may begin in middle age

• Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons

• Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death

Spinal CordSpinal Cord


• Extends from the medulla oblongata to the region of T12

• Below T12 is the cauda equina (a collection of spinal nerves)

• Enlargements occur in the cervical and lumbar regions

Figure 7.18

Spinal Cord AnatomySpinal Cord Anatomy

Slide 7.53a


• Exterior white mater – conduction tracts

Figure 7.19


Slide 7.53b


• Internal gray matter - mostly cell bodies

• Dorsal (posterior) horns

• Anterior (ventral) horns

Figure 7.19


Slide 7.53c


• Central canal filled with cerebrospinal fluid

Figure 7.19



• Meninges cover the spinal cord

• Nerves leave at the level of each vertebrae

• Dorsal root

• Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system

•Ventral root

Peripheral Nervous SystemPeripheral Nervous System


• Nerves and ganglia outside the central nervous system

• Nerve = bundle of neuron fibers

• Neuron fibers are bundled by connective tissue

Structure of a NerveStructure of a Nerve


• Endoneurium surrounds each fiber

• Groups of fibers are bound into fascicles by perineurium

• Fascicles are bound together by epineurium

Figure 7.20

Classification of NervesClassification of Nerves


• Mixed nerves – both sensory and motor fibers

• Afferent (sensory) nerves – carry impulses toward the CNS

• Efferent (motor) nerves – carry impulses away from the CNS

Spinal NervesSpinal Nerves


• There is a pair of spinal nerves at the level of each vertebrae.

Spinal NervesSpinal Nerves

Slide 7.64Copyright © 2003 Pearson Education, Inc. publishing as Benjamin CummingsFigure 7.22a

Autonomic Nervous SystemAutonomic Nervous System


• The involuntary branch of the nervous system

• Consists of only motor nerves

• Divided into two divisions

• Sympathetic division

• Parasympathetic division

Comparison of Somatic and Comparison of Somatic and Autonomic Nervous SystemsAutonomic Nervous Systems

Slide 7.69Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.24

Anatomy of the Autonomic Nervous Anatomy of the Autonomic Nervous SystemSystem


Figure 7.25

Autonomic FunctioningAutonomic Functioning

Slide 7.74a


• Sympathetic – “fight-or-flight”

• Response to unusual stimulus

• Takes over to increase activities

• Remember as the “E” division = exercise, excitement, emergency, and embarrassment

Autonomic FunctioningAutonomic Functioning

Slide 7.74b


• Parasympathetic – housekeeping activites

• Conserves energy

• Maintains daily necessary body functions

• Remember as the “D” division - digestion, defecation, and diuresis

Development Aspects of the Development Aspects of the Nervous SystemNervous System

Slide 7.75a


• The nervous system is formed during the first month of embryonic development

• Any maternal infection can have extremely harmful effects

• The hypothalamus is one of the last areas of the brain to develop

Development Aspects of the Development Aspects of the Nervous SystemNervous System

Slide 7.75b


• No more neurons are formed after birth, but growth and maturation continues for several years (new evidence!)

• The brain reaches maximum weight as a young adult

• However, we can always grow dendrites!

ppt on cns

Health & Medicine

ventricles of brain

brain spinal cordprotect

central canal of spinal

structurekeep brain

spinal cordcomposition

brain cnsmicrogliaspider

central nervous systemmr

lateral ventricles