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NERVOUS SYSTEM CLASS 6.pptx
- 1. NERVOUS SYSTEM CLASS 6 FUNCTIONSOF THE NERVOUS SYSTEM
- 2. • SENSORY FUNCTION –SENSATION IS THE AWARENESS OF CHANGES IN THE EXTERNAL AND INTERNAL ENVIRONMENT WHEN SENSORY IMPULSES REACH THE CORTEX, WE BECOME AWARE OF THEM. WHAT REACHES THE SPINAL CORD IS USEFUL FOR REFLEXES FUNCTIONS OF NERVOUS SYSTEM
- 3. • PERCEPTION – ISTHE CONSIOUS AWARENESS AND INTERPRETATION OF SENSATION. IT IS A CORTICAL FUNCTION. EACH UNIQUE TYPE OF SENSATION IS CALLED A SENSORY MODALITY. A PARTICULAR SENSORY NEURON CARRIES ONLY ONE PARTICULAR SENSATION. FUNCTIONS OF NERVOUS SYSTEM
- 4. • PROPRIOCEPTION: – SENSATIONWHICH ALLOWS PERCEPTION OF STATIC POSITION, BODY MOVEMENTS OF LIMBS AND HEAD. • SENSATION BEGINS AT THE SENSORY RECEPTOR AND THEY ARE SELECTIVE FUNCTIONS OF NERVOUS SYSTEM
- 5. • SENSATION – STIMULATIONOF THE RECEPTOR – TRANSDUCTION OF THE STIMULUS ( RECEPTOR TRANSMITS ENERGY INTO GRADED POTENTIAL) – WHEN THE POTENTIAL REACHES THE THRESHOLD, IT TRIGGERS IMPULSE WHICH IS PROPOGATED TO CNS – PARTICULAR REGION OF THE CNS RECEIVES THE IMPULSE, INTEGRATES AND PERCEPTION OCCURS FUNCTIONS OF NERVOUS SYSTEM
- 6. • SENSORY RECEPTORS –FREE NERVE ENDINGS e.g. PAIN, TEMPERATURE – ENCAPSULATED NERVE ENDINGS e.g. VISCERAL PAIN, PRESSURE – SPECIALISED CELLS e.g. VISION, TASTE etc. • ANOTHER CLASSIFICATION – EXTEROCEPTOR, ENTEROCEPTOR AND PROPRIOCEPTOR • SENSORY RECEPTORS SHOW ADAPTABILITY – IF THE STIMULUS IS MAINTAINED THE IMPULSE IS REDUCED GRADUALLY ; RAPID OR SLOW FUNCTIONS OF NERVOUS SYSTEM
- 7. • SOMATIC SENSATION –RECEPTORS IN THE SKIN OR SUBCUTANEOUS TISSUE ARE NOT EVENLY DITRIBUTED. – 4 TYPES OF SOMATIC SENSATION • TOUCH – TACTILE RECEPTORS DIFFERENTIATE BETWEEN FINE AND CRUDE TOUCH, PRESSURE AND VIBRATION, ITCH AND TICKLE. • THERMAL - COLD AND WARMTH, EPIDERMIS 10 TO 400, DERMIS 40 – 480, LESS THAN 100 AND MORE THAN 480 PAIN FUNCTIONS OF NERVOUS SYSTEM
- 8. • 4 TYPESOF SOMATIC SENSATION • PAIN – RECEPTORS ARE FREE NERVE ENDINGS. PRESENT IN ALL TISSUES EXCEPT BRAIN. TISSUE IRRITATION RELEASES CHEMICALS WHICH STIMULATE NOCICEPTORS. – TWO TYPES OF PAIN RECEPTORS – FAST AND SLOW. SUPERFICIAL SOMATIC PAIN AND DEEP SOMATIC PAIN. FAST PAIN IS LOCALISED TO SITE OF INJURY. DEEP PAIN IS DIFFUSE. VISCERAL PAIN IS REFERRED TO THE SURFACE • PROPRIOCEPTION = PERCEPTION OF BODY MOVEMENTS. IMPORTANT FOR MAINTAINING POSTURE AND BALANCE. – MUSCLE SPINDLE IS THE RECEPTOR FUNCTIONS OF NERVOUS SYSTEM
- 9. • SENSORY PATHWAYS –RELAY INFORMATION FROM RECEPTORS TO THE PRIMARY SOMATO SENSORY AREA IN THE CORTEX – 1ST ORDER NEURONS – FROM SENSE ORGAN TO BRAIN STEM OR SPINAL CORD– 2ND ORDER NEURONS FROM THERE TO THALAMUS THEY DECCUSATE. – 3RD ORDER NEURON IS FROM THALAMUS TO CORTEX. FUNCTIONS OF NERVOUS SYSTEM
- 10. • SENSORY PATHWAYS –SPINAL CORD HAS TWO COLUMNS – POSTERIOR COLUMN • FIRST ORDER NEURONS SYNAPSE IN THE MEDULLA • 2ND ORDER NEURONS DECCUSATE AND REACH MEDIAL LEMNISCUS ( MEDULLA TO THALAMUS TRACT) • 3RD ORDER NEURONS REACH CORTEX. – FINE TOUCH, STEREOGNOSIS ( ABILITY TO RECOGNISE OBJECT BY FEELING IT) FUNCTIONS OF NERVOUS SYSTEM
- 11. • ANTEROLATERAL PATHWAYS •SPINOTHALAMIC -3 ORDERS OF NEURONS – 1ST ORDER- CELL BODIES ARE IN THE POSTERIOR ROOT GANGLIA – 2ND ORDER – IN THE GREY HORN. DECCUSATION AT MEDULLA AND ASCENT – 3RD ORDER – FROM THALAMUS TO CORTEX • LATERAL SPINOTHALAMIC TRACT CARRY PAIN & TEMPERATURE • ANTERIOR CARRY CRUDE TOUCH & PRESSURE FUNCTIONS OF NERVOUS SYSTEM
- 12. • SOMATO SENSORYPATHWAY TO CEREBELLUM • POSTERIOR & ANTERIOR SPINO CEREBELLAR TRACTS • IMPORTANT IN MAINTAINING POSTURE, BALANCE, CO-ORDINATION AND SKILLED MOVEMENTS. FUNCTIONS OF NERVOUS SYSTEM
- 13. • MOTOR PATHWAYS –ALL THE SIGNALS THAT CONTROL THE MOVEMENT EXTEND OUT OF BRAIN STEM AND SPINAL CORD TO INNERVATE SKELETAL MUSCLES IN THE HEAD AND BODY. – THESE ARE LOWER MOTOR NEURONS. – INPUT FROM UPPER MOTOR NEURONS – OR INTER NEURONS CALLED LOCAL CIRCUIT NEURONS – THEY ARE IN THE BRAIN STEM OR SPINAL CORD. – RECIEVE INPUT FROM LOCAL SENSORY NEURONS FOR REFLEX OR FROM HIGHER CENTRES. – THEY CO-ORDINATE RHYTHMIC ACTIVITY FUNCTIONS OF NERVOUS SYSTEM
- 14. • UPPER MOTORNEURONS – FROM CORTEX – ESSENTIAL FOR PLANNING AND DIRECTING VOLUNTARY MOVEMENTS. – FROM RED NUCLEUS, SUPERIOR COLLICULUS, RETICULAR FORMATION, BASAL GANGLIA FOR INITIATION AND TERMINATION OF MOVEMENTS & MAINTENANCE OF MUSCLE TONE – FROM CEREBELLAR NEURON FROM CEREBELLUM – MONITORS THE DIFFERENCE BETWEEN INTENDED MOVEMENTS AND PERFORMED MOVEMENTS, POSTURE & BALANCE FUNCTIONS OF NERVOUS SYSTEM
- 15. • ORGANISATION OFUPPER MOTOR NEURONS DIRECT PATHWAY – CORTEX TO LMN – PYRAMIDAL PATHWAY – 90% DECUSSATE AT MEDULLA AND BECOME CONTRA LATERAL; 10% IPSILATERAL- DECUSSATE AT SPINAL CORD – LATERAL CORTICO SPINAL TRACTS FOR HANDS, FEET AND FINE MOVEMENTS. – ANTERIOR CORTICO SPINAL TRACTS FOR NECK & TRUNK – DO NOT DECUSSATE – CORTICO BULBAR – EYES, TONGUE AND NECK FUNCTIONS OF NERVOUS SYSTEM
- 16. • ORGANISATION OFUPPER MOTOR NEURONS INDIRECT PATHWAY – EXTRAPYRAMIDAL PATHWAY – COMPLEX POLYSYNAPTIC WITH CIRCUITS WHICH INVOLVE THE CORTEX, BASAL GANGLIA, THALAMUS, CEREBELLUM. RETICULAR FORMATION & RED NUCLEUS – FORM 5 MAJOR TRACTS: RUBEROSPINAL, TECTOSPINAL, VESTIBULOSPINAL, LATERAL & MEDIAL RETICULOSPINAL FUNCTIONS OF NERVOUS SYSTEM
- 17. • ORGANISATION OFUPPER MOTOR NEURONS INDIRECT PATHWAY – BASAL GANGLIA – SENSORY ASSOICATION AND MOTOR OUTPUT – MODULATE MOTOR MOVEMENTS AND SUPPRESSES UNWANTED MOVEMENTS – CEREBELLUM MAINTAINS POSTURE, BALANCE, LEARNING & PERFORMING MOVEMENTS. FUNCTIONS OF NERVOUS SYSTEM
- 18. • INTEGRATIVE FUNCTION •IS THE PROCESSING OF SENSORY INFORMATION BY ANALYSING, STORING & MAKING DECISIONS • SLEEP, AWAKE LEARNING, MEMORY, EMOTIONAL RESPONSE • AROUSAL – RAS IS STIMULATED BY PAINFUL STIMULII FUNCTIONS OF NERVOUS SYSTEM
- 19. • SLEEP • ISA STATE OF ALTERED CONSCIOUSNESS FROM WHICH ONE CAN BE AROUSED. • 2 PHASES - NREM & REM • NREM 4 STAGES: – STAGE 1 – TRANSITION – 1 – 7 MINUTES; IF WOKEN UP – “NOT SLEEPING” – STAGE II – LIGHT SLEEP WITH DREAMS – STAGE III – MODERATE DEEP SLEEP; BP, TEMP FALLS – DIFFICULT TO WAKE THE PERSON – STAGE IV – DEEP SLEEP -BRAIN METABOLISM IS DECREASED, SLEEPWALKNG OCCURS IN THIS STAGE. – STAGE IV REACHED IN ONE HOUR FROM THE BEGINNING FUNCTIONS OF NERVOUS SYSTEM
- 20. SLEEP • IN 7-8HOURS THERE ARE 3-5 EPISODES OF REM SLEEP. • EYES MOVE BACK & FORTH AND EACH EPISODE LASTS FOR 10 TO 12 MINUTES. • INFANTS HAVE MORE REM SLEEP • IMPORTANT FOR BRAIN METABOLISM. • BRAIN BLOOD FLOW AND METABOLISM INCREASE WHILE DREAMING. • CAFFIENE INHIBITS SLEEP • PARASYMPATHETIC ACTIVITY INCREASES SLEEP FUNCTIONS OF NERVOUS SYSTEM
- 21. LEARNING & MEMORY: •LEARNING- THE ABILITY TO ACQUIRE NEW INFORMATION OR SKILL THROUGH INSTRUCTIONS OR EXPERIENCE. • MEMORY – THE PROCESS BY WHICH THE INFORMATION ACQUIRED THROUGH LEARNING IS STORED AND RETRIEVED WHEN REQUIRED, • FOR AN EXPERIENCE TO BECOME MEMORY, IT MUST PRODUCE PERSISTENT STRUCTURAL AND FUNCTIONAL CHANGES IN THE NEURON. FUNCTIONS OF NERVOUS SYSTEM
- 22. PLASTICITY • IS THECAPACITY FOR CHANGE ASSOCIATED WITH LEARNING • OUR ABILITY TO CHANGE OUR BEHAVIOUR IN RESPONSE TO STIMULLI FROM INTERNAL ENVIRONMENT CAUSING : – CHANGE IN INDIVIDUAL NEURONS – SYSNTHESIS OF NEW PROTIEN – SPROUTING NEW DENDRITES FUNCTIONS OF NERVOUS SYSTEM
- 23. MEMORY • PART OFBRAIN ASSOCIATED WITH MEMORY ARE THE ASSOCIATION AREAS • IF A PARTICULAR ACTIVITY IS PRACTISED MORE OFTEN, THAT AREA DEVELOPS • IMMEDIATE MEMORY – ABILITY TO RECALL INFORMATION FOR SECONDS • SHORT TERM MEMORY – FEW MINUTES • (PROBABLY THERE ARE CHEMICAL CHANGES RATHER THAN STRUCTURAL • LONG TERM MEMORY – DAYS TO YEARS. CAN BE RECALLED ANY TIME. • FREQUENT RECALLING MAKES IT EASILY ACCESIBLE. • STORED IN CORTEX. ONLY 1% OF OUR EXPERIENCE IS STORED AS LONG TERM MEMORY FUNCTIONS OF NERVOUS SYSTEM