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NERVOUS SYSTEM

NERVOUS SYSTEM. FUNCTIONS. TO DETECT CHANGES AND FEEL SENSATIONS TO INITIATE APPROPRIATE RESPONSES TO CHANGE TO ORGANIZE INFORMATION FOR IMMEDIATE USE AND TO STORE IT FOR FUTURE USE. DIVISIONS OF THE NS. CNS INCLUDES BRAIN AND SPINAL CORD PNS

Melvin
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NERVOUS SYSTEM

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  1. NERVOUS SYSTEM

  2. FUNCTIONS • TO DETECT CHANGES AND FEEL SENSATIONS • TO INITIATE APPROPRIATE RESPONSES TO CHANGE • TO ORGANIZE INFORMATION FOR IMMEDIATE USE AND TO STORE IT FOR FUTURE USE

  3. DIVISIONS OF THE NS • CNS INCLUDES BRAIN AND SPINAL CORD • PNS INCLUDES CRANIAL NERVES, SPINAL NERVES, AND THE AUTONOMIC NERVOUS SYSTEM (ANS)

  4. PARTS OF A NERVE CELL • DENDRITES – TRANSMIT IMPULSES TOWARDS THE CELL BODY • CELL BODY – CONTAINS NUCLEUS • AXON – TRANSMIT IMPULSES AWAY FROM THE CELL BODY

  5. BETWEEN NERVE CELLS ARE SYNAPSES • NEUROTRANSMITTERS SUCH AS ACETYLCHOLINE CARRY THE IMPULSE ACROSS THE SYNAPSE • THESE ARE DESCRIBED AS A CHEMICAL TRANSMISSION

  6. WHAT’S SIMILAR IN THE CNS AND THE PNS? • BOTH CONTAIN THE MYELIN SHEATH (A SHEATH THAT ELECTRICALLY INSULATES NEURONS FROM ONE ANOTHER) • THE MYELIN SHEATH ALLOWS SMOOTH NERVE IMPULSE TRANSMISSION FROM ONE NEURON TO ANOTHER

  7. WHAT’S DIFFERENT IN THE CNS AND THE PNS? • CNS • THE MYELIN SHEATH IS FORMED BY OLIGODENDROCYTES, A SPECIALIZED CELL THAT CANNOT REGENERATE

  8. FOR EXAMPLE • THE PHRENIC NERVE – C3-C5

  9. WHAT’S DIFFERENT IN THE CNS AND PNS? • PNS • THE MYELIN SHEATH IS MADE OF SCHWANN CELLS • THE NUCLEI ARE OUTSIDE OF THE MYELIN SHEATH AND CALLED A NEUROLEMMA • THESE CAN REGENERATE

  10. THE REFLEX ARC • THE PATHWAY NERVE IMPUSLES TRAVEL WHEN A REFLEX IS ELICITED

  11. 5 ESSENTIAL PARTS TO REFLEX • RECEPTORS – DETECT STIMULUS AND GENERATE IMPULSE • SENSORY NEURON – CARRY IMPULSES TO THE CNS • CNS – CONTAINS 1 OR MORE SYNAPSES • MOTOR NEURON – CARRY IMPULSES FROM THE CNS TO THE EFFECTOR • EFFECTOR – PERFORMS ACTION

  12. STRETCH REFLEX • KEEPS OUR BODY UPRIGHT WITHOUT THINKING

  13. FLEXOR REFLEX • AKA WITHDRAWAL REFLEX • PREVENTS INJURY BY PULLING AWAY FROM A PAINFUL STIMULUS

  14. SPINAL CORD • TRANSMITS MESSAGES TO AND FROM THE BRAIN • EXTENDS FROM THE FORAMEN MAGNUM TO L2 • CALLED THE CAUDA EQUINA AFTER L2

  15. SPINAL CORD • THE CENTER OF THE CORD CONTAINS GRAY MATTER THAT CARRIES MOTOR IMPULSES • THE EXTERNAL PORTION OF THE CORD CONTAINS WHITE MATTER THAT CARRIES SENSORY IMPULSES

  16. SPINAL CORD • ASCENDING TRACTS CARRY SENSORY IMPULSES TO THE BRAIN (WHITE MATTER) • DESCENDING TRACTS CARRY MOTOR IMPULSES AWAY FROM THE BRAIN (GRAY MATTER) • THE CENTRAL CANAL CONTAINS CSF

  17. SPINAL NERVES • 31 PAIRS OF SPINAL NERVES 8 CERVICAL 12 THORACIC 5 LUMBAR 5 SACRAL 1 COCCYGEAL

  18. SPINAL NERVES • EACH SPINAL NERVE HAS 2 ROOTS • THE DORSAL ROOT CARRIES IMPULSES IN TO THE CORD • THE VENTRAL ROOT CARRIES IMPULSES OUT OF THE CORD

  19. BRAIN • CEREBRUM – LARGEST PART OF THE BRAIN • THE TWO HEMISPHERES ARE CONNECTED BY THE CORPUS CALLOSUM THAT CONNECTS THE RIGHT AND LEFT HEMISPHERES • THERE IS A LATERAL VENTRICLE IN EACH HEMISPHERE

  20. CEREBRUM • THE CEREBRAL CORTEX (SURFACE) IS FOLDED EXTENSIVELY WITH GYRI THAT ALLOWS MILLIONS MORE NEURONS

  21. CEREBRUM • 4 LOBES • FRONTAL – MOTOR AREAS • PARIETAL – SENSORY AREAS • TEMPORAL – AUDITORY AND OLFACTORY AREAS • OCCIPITAL – VISUAL AREA

  22. PITUITARY – CONTROLS GROWTH • THALAMUS – INTEGRATES SENSATIONS • HYPOTHALAMUS – MANY FUNCTIONS • CEREBELLUM – COORDINATION, POSTURE, EQUILIBRIUM • VENTRICLES (4) – CONTAINS THE CHOROID PLEXUS THAT MAKES CSF

  23. BRAINSTEM • MIDBRAIN – VISUAL AND AUDITORY REFLEXES • PONS – 2 RESPIRATORY CENTERS FOR NORMAL BREATHING • MEDULLA OBLONGATA – REGULATES HEART RATE, BLOOD PRESSURE, AND RESPIRATION. ALSO A REFLEX CENTER FOR COUGHING, SNEEZING, SWALLOWING, VOMITING

  24. CONNECTIVE TISSUE MEMBRANES • COVER BRAIN AND SPINAL CORD • CALLED MENINGES • 3 LAYERS • DURA MATER – THICK OUTER LAYER • ARACHNOID MEMBRANE – MIDDLE LAYER • PIA MATER – INNERMOST LAYER • SUBARACHNOID SPACE – CONTAINS CSF

  25. CSF • CEREBROSPINAL FLUID • BRINGS NUTRIENTS TO CNS NEURONS AND REMOVES WASTES TO THE BLOOD • ACTS AS A CUSHION FOR CNS

  26. CRANIAL NERVES • 12 PAIRS • EMERGE FROM THE BRAIN STEM OR OTHER PARTS OF THE BRAIN

  27. CN I – OLFACTORY CN II – OPTIC CN III – OCULOMOTOR CN IV – TROCHLEAR CN V – TRIGEMINAL CN VI – ABDUCENS CN VII – FACIAL CN VIII – ACOUSTIC CN IX – GLOSSOPHARYNGEAL CN X – VAGUS CN XI – ACCESSORY CN XII - HYPOGLOSSAL

  28. AUTONOMIC NERVOUS SYSTEM • PART OF THE PNS • 2 DIVISIONS • SYMPATHETIC • PARASYMPATHETIC THESE ARE INTEGRATED BY THE HYPOTHALAMUS

  29. SYMPATHETIC – “FIGHT OR FLIGHT”, DOMINATES DURING STRESSFUL SITUATIONS • PARASYMPATHETIC – DOMINATES DURING NONSTRESSFUL SITUATIONS AND INCREASES PERISTALSIS DURING DIGESTION

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