ANATOMY AND PHYSIOLOGY OF C

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ANATOMY AND PHYSIOLOGY OF C.N.S : 

ANATOMY AND PHYSIOLOGY OF C.N.S Presented By: Dr Randeep Dhaliwal. Moderated By: Dr Parmanand.

ANATOMICAL CLASSIFICATION : 

ANATOMICAL CLASSIFICATION NERVOUS SYSTEM CNS. PNS ANS. Cerebral Hemispheres. Spinal nerves. Brain stem. Spinal cord.

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Cerebral cortex. : 

Cerebral cortex. Two cerebral hemispheres constitute the cerebral cortex. The Sensory, Motor and Associational information is processed. Volume and Mass wise largest of all.

BRAIN STEM Medulla: Crossing over of Pyramidal tract. Pons: Seat for respiratory and other vital centers. Thalamus: Relay station for most afferent impulses before they are transmitted to cerebral cortex. Limbic system: Explained ahead. R.A.S: Determines the over all activity of CNS including wakefulness and sleep . Mostly cholinergic fibers. Cerebellum: Explained ahead. : 

BRAIN STEM Medulla: Crossing over of Pyramidal tract. Pons: Seat for respiratory and other vital centers. Thalamus: Relay station for most afferent impulses before they are transmitted to cerebral cortex. Limbic system: Explained ahead. R.A.S: Determines the over all activity of CNS including wakefulness and sleep . Mostly cholinergic fibers. Cerebellum: Explained ahead.

LIMBIC SYSTEM. : 

LIMBIC SYSTEM. Lies just beneath the Cerebral Cortex, and above the Thalamus. ACTION: It integrates the emotional state with Motor and Visceral Activities. NUCLEI INCLUDES: Hippocampus, Basal Ganglia, Amygdella.

BASAL GANGLIA. : 

BASAL GANGLIA. It constitute a group of interconnected nuclei which are GABAnergic and DOPAMINErgic neurons. NUCLEI: ASSOCIATED DEFECTS SUBSTANTIA NIGRA: PARKINSONISM. GLOBUS PALLIDUS: PUTAMEN: CHOREA. CAUDATE NUCLEUS: SUBTHALAMIC NUCLEUS: STRITUM / LENTICULAR NUCLEUS

BASAL GANGLIA.It mantains the balance between the agoinst and antagonist muscles in normal life.Destruction of basal ganglia or any of its components ( eg in Parkinsonism) the muscle rigidity becomes evident. : 

BASAL GANGLIA.It mantains the balance between the agoinst and antagonist muscles in normal life.Destruction of basal ganglia or any of its components ( eg in Parkinsonism) the muscle rigidity becomes evident.

CEREBELLUM : 

CEREBELLUM Operates subconsciously to monitor and elicit corrective responses in the motor activity caused by stimulation of part brain and spinal cord. Fine tunes the coarse skeletal muscle movement which is much needed in trained and artistic works. Spinocerebellar pathways conduct @ > 100 m/s. Which is the fastest conduction system in the CNS. Equilibrium and posture mantainence.

SIGNS OFCEREBELLAR DYSFUNCTION : 

SIGNS OFCEREBELLAR DYSFUNCTION Past Pointing. Intentional Tremors. Dysmetria. Dysarthria. Ataxia. Dysdhocokinesia. Cerebellar Nystagmus.

SPINAL CORD. : 

SPINAL CORD.

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SPINAL CORD : 

SPINAL CORD SPINAL CORD GREY MATTER WHITE MATTER DORSAL COLUMN. > DORSAL HORN. LATERAL COLUMN. > LATERAL HORN. VENTRAL COLUMN. > ANTERIOR HORN.

GREY MATTER. : 

GREY MATTER. There are nine layers in grey matter of spinal cord. In the Anterior horn cells of grey matter ALPHA and GAMMA MOTORS that leave the spinal cord anterior ( ventral) nerve roots and innervate skeletal muscles. RENSHAW CELLS these are the intermediate neurons, that provide nerve fibers that synapse in the grey matter with the anterior horn cells.

RENSHAW CELLS inhibits the action of anterior motor cells from excessive activity. The PREGANGLIONIC FIBERS of Sympathetic nervous system are located in the lateral horns of the THORACOLUMBAR portions of the spinal cord. Layer II AND III OF spinal cord, (in the posterior horn) transmits the Pain, Temp, and Tactile Stimulus. Layer v of spinal cord has OPOIDS receptors. : 

RENSHAW CELLS inhibits the action of anterior motor cells from excessive activity. The PREGANGLIONIC FIBERS of Sympathetic nervous system are located in the lateral horns of the THORACOLUMBAR portions of the spinal cord. Layer II AND III OF spinal cord, (in the posterior horn) transmits the Pain, Temp, and Tactile Stimulus. Layer v of spinal cord has OPOIDS receptors.

TRACTS : 

TRACTS ASSENDING TRACTS DORSAL COLUMN SENSORY IMPULSES. FROM PEREPHERY TO THE BRAIN Eg: SPINOTHALAMIC. SPINOCEREBELLAR. SPINORETICULAR. DESCENDING TRACTS LATERAL AND ANTERIOR COLUMNS MOTOR IMPULSES. FROM BRAIN TO PEREPHERY. Eg: CORTICOSPINAL.

NEURONS : 

NEURONS

CLASSIFICATION OF NEURONS : 

CLASSIFICATION OF NEURONS NEURON TYPE A TYPE B TYPE C ALPHA NON MYELINATED BETA GAMMA DELTA

TYPE A FIBERS. : 

TYPE A FIBERS. LARGEST DIAMETER AND PROBABLY FASTEST. a : Innervates the skeletal muscle. ß : Tactile sensation receptors Eg Pacinian, Mesinier ? : Skeletal muscles spindles. d : Touch and Fast pain are transmitted through this. TYPE C TRANSMITES SLOW PAIN STIMULUS AND ARE THE ONLY FIBERS THAT ARE NON MYELINATED.

CEREBRAL BLOOD FLOW : 

CEREBRAL BLOOD FLOW Avg 50ml/100gm/min. For Adult it comes out as avg of 750ml/100gm/min. Which is nearly 15% of resting Cardiac Output. GREY MATTER : about 80ml/100gm/min. WHITE MATTER: about 20ml/100gm/min. C.M.R.O: Nearly 3-5ml/100gm/min. So we can say CBF nearly Parallels CMRO. PaCO2 & PaO2 influences CBF. 1mm hg rise in PaCo2 nearly 1-2ml/100gm/min CO2 + H2O Bicarb + Proton. Vasodilation.

AUTOREGULATION : 

AUTOREGULATION B/W mean Arterial Pr of 60 – 140 mm Hg.(MAP). Chronic systemic hypertension shifts the curve to right, i.e, a reduction in CBF in these cases can occur even at a pressure > 60 mm hg mean. Auto regulation of CBF IS ABOLISHED BY: HYPERCAPNIA. ARTERIAL HYPOXEMIA. VOLATILE ANESTHETIC AGENTS AREA SURROUNDING ACUTE CEREBRAL INFACT.: Here the vessels are fully dilated already.(luxury perfusion)

CEREBROSPINAL FLUID : 

CEREBROSPINAL FLUID Normal ICP < 15 mm Hg. Total volume : 150 ml. Specific Gravity: 1.002 to 1.009. Major Function: cushion the brain in cranium. FORMATION OF CSF: In CHOROID PLEXUS of all the 4 ventricles. @ 30 ml/ hr. Elctrolyte composition: Na & Cl 7%. more K & Glucose 40% less.

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REABSORPTION OF CSF. Almost all CSF formed each day is reabsorbed into the venous circulation via the specialised structures known as ARACHENOID VILLI. These villi project subarachenoid spaces into the venous sinusesof the brain and often in veins of spinal cord. Magnitude of reabsorption depends on the pressure gradient between the CSF and venous circulation.

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CIRCULATION: LATERAL VENTRICLE THIRD VENTRICLE. TOWARDS CEREBRUM. FOURTH VENTRICLE. SUBARACHENOID SPACE. CISTERNA MAGNA. FORAMEN OF MONERO AQUEDUCT OF SYLVIUS CISTERNA MAGNA FORAMEN OF MEGENDIE

BLOOD BRAIN BARRIER. : 

BLOOD BRAIN BARRIER. A Protective mechanism for the brain so that a different suitable mechanism is maintained in the brain despite alteration in body. Formed by tight junctions by Glial cells & the capillary endothelium of the brain. Structures outside the BBB: Posterior Pitutary. CTZ Organum Vesiculosum, Area Postrema.

THANK YOU. : 

THANK YOU.

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