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More on the nervous system Central nervous system spinal cord brain Cranial and spinal nerves Autonomic nervous system

More on the nervous system Central nervous system spinal cord brain Cranial and spinal nerves Autonomic nervous system. Nerve pathways afferent nerves (sensory) INTO CNS via dorsal (posterior)root of peripheral nerve efferent (motor) FROM CNS via ventral

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More on the nervous system Central nervous system spinal cord brain Cranial and spinal nerves Autonomic nervous system

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  1. More on the nervous system Central nervous system spinal cord brain Cranial and spinal nerves Autonomic nervous system

  2. Nerve pathways afferent nerves (sensory) INTO CNS via dorsal (posterior)root of peripheral nerve efferent (motor) FROM CNS via ventral root of peripheral nerve (anterior) may be simple arc, or move longtudinally or transversely within gray matter of spine

  3. A reflex arc

  4. Brain and spine are protected by skeleton Meninges formed between skeleton and tissue, provide additional protection Subarachnoid space filled with cerebrospinal fluid (CSF) formed by choroid plexus also fills ventricles in brain

  5. Cerebrospinal fluid protects the central nervous system

  6. Organization of spinal cord 31 pairs of spinal nerves innervate specific parts of body Tracts from muscles to brain, and back again Corticospinal (pyramidal)- movement Extrapyramidal- balance and posture Spinothalamic- “generalized” sensory information

  7. Ascending (sensory) and descending (motor)

  8. Brain Cerebrum- sensory, motor, higher order function Midbrain, diencephalon, etc- processing sensory information, other integrative function Cerebellum- coordinating voluntary movement Pons- respiratory regulation Medulla oblongata- various visceral organs (heart, lungs)

  9. Cerebrum Left and right hemispheres Separated by falx cerebri Connected by corpus callosum Functional regions sensory motor association

  10. Crossover in brain stem: right hemisphere controls movement of left side, etc. Corpus callosum allows communication between hemispheres Most people have a dominant hemisphere

  11. Basal nuclei • Direct and modify motor response • Parkinson’s disease: lack of dopamine- movement is inhibited (region becomes OVERactive • Huntingdon’s disease: basal nuclei degrade

  12. Diencephalon- a small area of the brain, but a lot is happening! Thalamus- filters and directs sensory information Pituitary gland- many hormones Hypothalamus-homeostasis Limbic system- hypothalamus, thalamus, basal nuclei, hippocampus, amygdala “Survival instincts”, emotions, memory (fear, anger, aggression, sex drive)

  13. Regions of the brain

  14. Brain stem midbrain- reflex centers nerve tracts pons- tracts, regulation of breathing rate and depth medulla oblongata- cardiac, respiratory, digestive, vasomotor (blood supply) Reticular formation- wakefulness (RAS) Cerebellum- coordination

  15. Drugs and the nervous system (see p. 245) Depressants affect neurotransmitter secretion Barbituates act throughout brain, especially on RAS Benzodiazepines (“tranquilizers”) depress limbic system and RAS Opiates- stimulate opioid receptors, relieve pain Cannabinoids- release inhibitions, depress higher brain centers

  16. Stimulants vary in mechanisms Cocaine- affects serotonin and dopamine levels Amphetamine- adrenalin (epinephrine) levels Caffeine- systemic Nicotine- affects serotonin, dopamine and hormone secretion Why are they addictive?

  17. How does the brain communicate with the rest of the body? • Peripheral nervous system • Cranial • Spinal • Sensory • motor

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