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Nervous system

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  1. Nervous system “Let’s get wired!”

  2. Divisions • Central Nervous System – CNS • Brain and spinal cord • Peripheral Nervous System • Outer region – cranial/spinal origination

  3. A vs E • Afferent nerves – incoming senses • Efferent nerves – outgoing motor

  4. Innervation • Somatic - skeletal • Autonomic – visceral – smooth/cardiac/glands • Sympathetic – fight or flight response – immediate threat • Parasympathetic – resting/regroup activities

  5. Anatomy of the brain and spinal cord • Skull • Meninges • Dura - epidural/subdural space • Arachnoid – subarachnoid space • Pia

  6. Cerebrospinal fluid • Protection of the brain and spinal cord • Circulates chemicals for internal brain function – ie. CO-2 changes will cause medulla oblongata to accommodate respiratory function to meet body needs for homeostasis • Mainly found in subarachnoid space and ventricles (4) two in cerebrum, one medial/below these, and one in cerebellum (brainstem) • Formed in choroid plexus – extracted from blood

  7. Circulation of CSF • Formed in choroid plexus • Ventricles • Central canal/subarachnoid space • Absorbed back into the blood • Normal adult CSF fluid is 140 ml

  8. Lumbar puncture • CSF from subarachnoid space in L3-4 • Pt. in R/L lateral fetal position or sitting on bedside • Pt. remains flat X 12 hrs. after procedure • Blood patch sometimes required • Tests for infection, disease

  9. Epidural

  10. Hydrocephalus • Congenital / tumor • Ventricles malfunction and disallow normal CSF flow • 1-3:1000 births

  11. Low intensity radiation

  12. Ventricula

  13. 1.Describe the difference between a spinal block and an epidural. 2. What is “hydrocephalus” and how can it be treated?

  14. Structure of the spinal cord • Protected by vertebral column • Extends from foramen magnum to the distal end of the first lumbar (45 cm – 18 in.) • Spinal cavity includes: cord, blood vessels, adipose tissue, meninges, and CS fluid • Split into two symmetrical halves – anterior surface is deeper and wider than the posterior surface • Nerve roots project from each side of cord

  15. Cont. • Dorsal nerve root – sensory information to cord • Ventral nerve root – motor information out of the cord • Each side of the cord the dorsal and ventral nerve roots join together to form a spinal nerve (peripheral)

  16. Spinal cord functions • Conducts information to and from the brain • Integrator – reflex center – for all spinal reflexes • Refer to ascending/descending tracts pgs. 382-383

  17. Brain • One of the largest vital adult organs • Weighs 3 lbs. • 100 billion neurons/900 glia (support cells) – also called neuoglia • Mitotic division only occurs in-utero and first few months post-natal • Cells will mature, but not increase in number • Maturity by 18 y.o.

  18. How would pre-natal malnutrition affect the fetus?

  19. Brain – six divisions • Medulla oblongata • Pons • Midbrain • Cerebellum • Diencephalon • Cerebrum

  20. Brainstem Composed of: Medulla oblongata Pons Midbrain

  21. Underside of the brain, showing the brainstem and cranial nerves

  22. Internal view of the lower brain

  23. Medulla oblongata • Attaches to spinal cord • An extension of the spinal cord above the foramen magnum • One inch in size • Separated from the pons by horizontal groove • Controls cardiac, respiratory and vasomotor function • Non-vital reflexes – vomiting, cough, sneeze swallow

  24. Pons • Above the medulla oblongata • Motor control • Sensory analysis • Reflex mediator for the 5th-8th cranial nerves • Helps with respiratory regulation

  25. Midbrain • Mesencephalon • Above the pons and below the cerebrum • Vision, hearing, eye movement, body movement

  26. Functions of the cerebellum • Second largest part of the brain • Located below the posterior section of the cerebrum • Responsible for movement coordination – smooth, precise and steady as to force, rate and extent • Posture • Balance – equilibrium receptors from ear

  27. Disease of the cerebellum • Abscess, hemorrhage, tumor, trauma • Ataxia – muscle incoordination • Hypotonia • Tremors • Gait disturbance • Balance disturbance – staggering, lurching, raising foot to high to step, bringing foot down very hard

  28. Diencephalon • Between the cerebrum and midbrain • Includes thalmus,hypothalmus, optic chiasma, and pineal body • Also known as the “emotional brain” or limbic system

  29. Thalamus • Processes auditory and visual signals • Relay station for sensory perception to cerebrum • Conscious recognition of pain, temperature and touch • Partly responsible for emotions by associating sensory impulses with feelings of pleasant vs unpleasant • Part in arousal/alerting mechanism • Part in complex reflex movement

  30. Hypothalmus • Autonomic center – visceral • Sense of smell • Link between mind and body • Pleasure/reward center – eating, drinking, sex • Relay station between cerebral cortex and autonomic centers • Mind over matter philosophy – psychosomatic disease – positive/negative • Regulates pituitary – renal function • Hormone regulation • Maintains wake state • Appetite regulation • Regulation of body temperature

  31. Pineal body • Above the midbrain • Looks line pine cone • Function not well understood • Regulates biological clock • Produces melatonin – synchronize various body functions with each other and external stimuli – such as onset of puberty and menses – also helps with light perception – called the “third eye”

  32. Complete handout Due next class!