DR ZAHOOR ALI SHAIKH LECTURE 1 1 First We Will Discuss ORGANIZATION amp CELLS OF NERVOUS SYSTEM then we will talk about Overview of Central nervous system CNS 2 ORGANIZATION OF NERVOUS SYSTEM ID: 910384
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ORGANIZATION OF NERVOUS SYSTEM
DR. ZAHOOR ALI SHAIKH LECTURE--- 1
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Slide2First We Will Discuss ‘ORGANIZATION & CELLS OF NERVOUS SYSTEM’ then we will talk about ‘Overview of Central nervous system’ [CNS]2
Slide3ORGANIZATION OF NERVOUS SYSTEMThe Nervous system is organized into
1. Central Nervous System (CNS) -- BRAIN -- SPINAL CORD
2.
Peripheral Nervous System
-- Nerve fibers that carry information between CNS and other parts of body at periphery.
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Slide4Organization of nervous system 4
Slide5CNSCentral nervous system regulates body activities. CENTRAL NERVOUS SYSTEM
1) BRAIN 2) SPINAL CORD
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Slide6PERIPHERAL NERVOUS SYSTEM PNS
Peripheral Nervous System is sub divided into 1) Afferent Division (Sensory) – which carry information to CNS
2)
Efferent Division (Motor) – which carry information from CNS to muscle and glands.
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Slide7PNS [cont]Efferent (Motor) division of PNS is further divide into --Somatic Nervous System
– it is under our voluntary control E.g. fibers of motor neuron that supply skeletal muscle. --Autonomic Nervous System – it is not under our control ( involuntary) and supply smooth muscle and glands.
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Slide8PNS [cont]Autonomic Nervous System (ANS) ANS– supplies cardiac muscle, smooth - muscle, glands.
ANS is divided into 1) Sympathetic ANS
2)
Parasympathetic ANS
Enteric ANS– in the wall of digestive tract
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Slide9ORGANIZATION OF NERVOUS SYSTEM9
Slide10PERIPHERAL NERVOUS SYSTEMNeurons in peripheral nervous system transmit signals between the central nervous system and receptors ,and Effectors in the body.In Peripheral Nervous System, there are 12
pairs of cranial nerves.There are 31 pairs of spinal nerve, from spinal cord. - 31 pair of Spinal nerve exit from cervical (8 pairs), thoracic (12 pairs), lumber (5 pairs), sacral (5 pairs), and coccygeal (1 pair).
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Slide1111
CRANIAL NERVES
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Cranial Nerves12 pairs
Slide1313
Spinal Nerves
31 pairs
Slide14FUNCTIONAL CLASSES OF NEURONS
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Slide15FUNCTIONAL CLASSES OF NEURONSThere are THREE functional types of Neurons
1) Afferent Neurons– which carry information to CNS. 2) Efferent Neurons– which carry information away from CNS (to the periphery).
3)
Interneurons– They form interactive net-work between neuron.
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Slide16FUNCTIONAL CLASSES OF NEURON16
Slide17AFFERENT NEURONAfferent Neuron has sensory RECEPTOR , that generates action potential in response to a particular stimulus. Sensory impulse are taken by axon toward the spinal cord.
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Slide18EFFERENT NEURONEfferent Neuron lies in the peripheral nervous system. It has cell body in the CNS . Efferent axon leaves the cell body and goes to innervate muscle.
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Slide19INTERNEURONSInterneurons lie in the CNS. About 99% of all neurons are Interneurons. Human CNS has more than 100 billion Interneurons.
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Slide20GLIAL CELLS OR NEUROGLIA20
Slide21GLIAL CELLS or NEUROGLIAGlial cells are connective tissue of CNS. Glial cells support the interneurons physically, metabolically, and functionally.
They do not conduct nerve impulses. Glial cells are of FOUR types.
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Slide22GLIAL CELLS or NEUROGLIA (cont)There are 4 type of Glial Cells 1. Astrocytes 2. Oligodendrocytes
3. Microglia 4. Ependymal Cells
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Slide23GLIAL CELLS23
Slide24Important Functions Of Glial Cells1. Astrocytes
Functions i. Formation of blood – brain – barrier
ii.
Formation of neural scar tissue
2.
Oligodendrocytes
Functions
i
. Forms
myelin sheath in the CNS
.
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Slide25Important Functions Of Glial Cells3. Microglia
Functions i. Phagocytosis [defense cells of CNS]
ii
. Release nerve growth factor.
4.
Ependymal Cells
Functions
i
.
Formation of Cerebrospinal fluid
[CSF].
ii
. Work as Neural Stem Cell – to form new neurons and glial cells.
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Slide26Protection Of The Brain26
Slide27Protection Of Brain As CNS is very delicate, it is protected by – skull bone [covers the brain] and Vertebral column [surrounds the spinal cord].
Meninges – cover brain and spinal cord. Meninges lie between bony covering [outside] and nervous tissue [inside]. Meninges are Durameter, Arachnoid and Piameter.CSF - Cerebro Spinal Fluid is present in subarachnoid space. CSF works as cushion.
Blood - brain barrier – it selectively allows the materials to pass to brain.
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Slide28MENINGES & CSF28
Slide29Cerebro Spinal Fluid [CSF]
It surrounds brain and spinal cord.It is present in subarachnoid space.It is formed by choroid plexuses [capillaries in the piameter] of ventricles in the brain.Volume of CSF is about 125 – 150 ml.
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Slide30CSF [cont]Clinical NoteHydrocephalus [water in the brain].Occurs if CSF accumulates more, due to the block in its circulation or reabsorption.
If hydrocephalus is untreated, increased CSF pressure can lead to brain damage and mental retardation. Treatment – surgically shunting the excess CSF to veins elsewhere in the body.
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Slide31‘Important Information’Brain function depends on 1. Oxygen
2. GlucoseBrain needs continuous supply of O2 and Glucose.Brain damage results if - brain gets no O2 supply for 4 to 5mins
or
- no glucose supply for 10 to 15mins.
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Slide32OVER VIEW OF CENTRAL NERVOUS SYSTEM (CNS)32
Slide33OVER VIEW OF CNSParts of Brain (from top to bottom) 1. Forebrain
a) Cerebrum i) Cerebral cortex ii) Basal nuclei b)
Diencephalon
i) Thalamus
ii) Hypothalamus
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Slide34OVERVIEW OF CNS (cont)Parts of Brain (cont) 2. Brain stem
- Mid brain - Pons - Medulla 3. Cerebellum
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Slide35MAJOR COMPONENTS OF THE BRAIN
Slide36CEREBRUMCerebrum constitutes 80% of total brain weight.Outer layer, i.e. cerebral cortex of cerebrum is highly convoluted. It has
gyri [ridges] and sulci [depression].
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Slide38Basal NucleiBasal Nuclei are present deep in the cerebrum.Functions: - Co-ordination of movements
- Muscle tone regulation
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Slide39Diencephalon Diencephalon is present in the interior of cerebrum.It has 2 components: - Thalamus
- HypothalamusThalamusAll sensory information passes.
Crude awareness of sensation.
Hypothalamus
Regulates body temperature, has thirst and food intake center, regulates autonomic nervous system.
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Slide40Brain StemBrain Stem [mid brain, Pons, Medulla].Brain Stem is continuous below with spinal cord.
Functions:Majority of cranial nerves originate from brain stem.Control Center for cardiovascular, respiratory system.Regulation of postural reflexes.Role in sleep – wake cycle.
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Slide41CerebellumCerebellum is attached at the back portion of brain stem.Functions:Balance of body.
Muscle tone.Co-ordination and planning of skilled movements e.g. dance.
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Slide43CEREBRUMCerebrum is the largest portion human brain. It is divided into TWO halves, Right and Left cerebral hemispheres. They are connected by CORPUS CALLOSUM which consists of about 300 million axons connecting two cerebral hemispheres. Cerebral cortex– It is the outer shell of Gray matter covering the inner white matter.
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Slide44CEREBRUM (cont)Q—What is the GRAY Matter ? A
– It is the Cerebral cortex , which consists of cell bodies of neuron and their dendrites, as well as connective tissue glial cells. Q– What is the WHITE Matter ?
A
– It is the myelinated nerve fibers (Axons) . Its white appearance is due to Myelin sheath (lipid layer).
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Slide45CEREBRAL CORTEX NOTE – Gray matter of cerebral cortex is like computers of CNS.
White matter is like wires that connect the computers to each other. 45
Slide46CEREBRAL HEMISPHEREEach cerebral hemisphere is divided into FOUR LOBES. 1) Frontal lobe 2)
Parietal lobe 3) Temporal lobe 4) Occipital lobe
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Slide4747
Cortical Lobes
Slide48LOBES OF BRAINCentral Sulcus separates the Frontal and Parietal lobe . Frontal Lobe It is
located at the front and at the top. It has MOTOR CORTEX area in the PRE -CENTRAL GYRUS- which controls the motor activity.Motor speech area
.
Elaboration of Thought.
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Slide49LOBES OF BRAINParietal lobe It is located posterior to the central sulcus.It has
sensory cortex at post central gyrus.Temporal LobeLocated laterally [on the sides of head].
It has
auditory cortex
.
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Slide50LOBES OF BRAINOccipital Lobe Located posteriorly [back of head].It has
visual cortex ( center).
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Slide5151
Functional areas of Cerebral cortex
Slide52Thank you52