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The brain

The brain. Anatomy & Physiology. Brain: unremarkable appearance ~ 3 lbs 4 major regions. 1. Cerebral Hemisphere. right & left connected by large fiber tract: corpus callosum cover most of other 3 parts

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The brain

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  1. The brain Anatomy & Physiology

  2. Brain: unremarkable appearance ~ 3 lbs 4 major regions

  3. 1. Cerebral Hemisphere • right & left connected by large fiber tract: corpus callosum • cover most of other 3 parts • surface: elevated ridges = gyriseparated by shallow grooves = sulci • Fissures deeper grooves separate regions of brain

  4. Gyri, Sulci, & a Fissure

  5. Longitudinal Fissure • separates cerebral hemispheres • other fissures separate brain into lobes

  6. Ventricles of the Brain • spaces in brain filled with CSF • connected to subarachnoid space (around brain & spinal cord) and central canal of spinal cord

  7. Somatic Sensory Area • parietal lobe posterior to central sulcus • receives impulses from sensory receptors (not special senses), interprets them • pain recognition • temperature • light touch

  8. Humunculus

  9. Primary Motor Area • anterior to central sulcus in frontal lobe • major voluntary motor tract

  10. Humunculus

  11. Occipital Lobe • visual area

  12. Temporal Lobe • auditory & olfactory areas

  13. Frontal Lobe • Brocca’s Area: ability to speak • @ base of precentralgyrus (usually only on left side) • injury  inability to correctly vocalize words

  14. Frontal Lobotomy

  15. Frontal Lobotomy • http://www.youtube.com/watch?v=_0aNILW6ILk

  16. Phineas Gage • http://www.youtube.com/watch?v=c6kRP41ygrI

  17. Lobe Functions • anterior frontal lobe: higher intellectual reasoning • complex memories: frontal/ temporal lobe • all facets of speech: occipital/temporal/parietal lobes

  18. Gray Matter of the Brain

  19. Basal Nuclei • gray matter in brain that is NOT in cerebral cortex • functions: help regulate voluntary motor activity by modifying instructions sent to skeletal muscle by primary motor cortex

  20. Imbalances in Basal Nuclei • Parkinson’s • Huntington’s

  21. 2. Diencephalon

  22. Diencephalon • sits atop brain stem • enclosed by cerebral hemispheres • major parts: • Thalamus • Hypothalamus • Limbic system • Epithalamus

  23. Thalamus • relay station for sensory impulses passing thru to sensory cortex

  24. Hypothalamus • ANS center • role in: • temperature control • water balance • metabolism

  25. Limbic System: forms rim surrounding corpus callosum

  26. Limbic System • regulates autonomic & endocrine functions in response to emotional stimuli (“reacting” brain vs. cerebral cortex being “thinking” brain) • set level of arousal • motivation • reinforcing behaviors • rage, love, memory, empathy

  27. Brain Stem • ~size of thumb in diameter & ~ 3 inches long • 3 parts: • midbrain • pons • medulla oblongata

  28. Choroid Plexus • knots of capillaries w/in each ventricle • produce & secrete CSF (cerebral spinal fluid)

  29. Midbrain • smallest, uppermost part of brain stem • cerebral aquaduct: tiny canal that runs thru midbrain connecting 3rd & 4th ventricles • contains reflex centers for vision, hearing

  30. Midbrain

  31. Pons • “bridge” • rounded structure that protrudes below midbrain • contains apneustic (produces deep, prolonged inspirations) & pneumotatic center (inhibits inspiration)

  32. Medulla Oblongata • most inferior part of brain stem • inferior border merges into spinal cord • centers: heart rate, BP, breathing, swallowing, vomiting

  33. Cerebellum • large, cauliflower-like • projects dorsally from under occipital lobe • 2 hemispheres • convoluted surface • provides precise timing for skeletal muscle activity • controls balance & equilibrium

  34. Traumatic Brain Injuries • Head injuries are leading cause of accidental death in USA. • Concussion: dizziness, “see stars”, briefly lose consciousness; No permanent brain damage • Contusion: result of marked tissue damage. Cerebrum: may maintain consciousness Brainstem: coma • Cerebral Edema: swelling of brain due to inflammatory response to injury/ initially conscious neuro signs deteriorate (think edema or hemorrhage)

  35. Cerebrovascular Accident(CVA) • stroke • 3rd leading cause of death in USA • occur when blood circulation to brain is interrupted • vessel could be blocked (temporary or permanent) or hemorrhaging

  36. CVA • characterized by: • abrupt onset of persisting neurological symptoms that arise from destruction of brain tissue common causes: • intracerebral hemorrhage • emboli • atherosclerosis of cerebral arteries

  37. CVA Risk Factors hypertension hypercholesterolnemia heart disease narrowed carotid arteries hx of TIAs (transient ischemic attacks) diabetes smoking obesity excessive alcohol intake

  38. CVA Treatments • Thrombolytic: • clot-dissolving drug: tissue plasminogen activator (t-PA) greatly improved prognosis for CVA • aspirin (makes plts slippery  fewer clots) • blood thinners

  39. Sequelae of CVA • Aphasia: from damage to left side cerebrum where language centers are • Motor Aphasia: • damage to Broca’s area • loss of ability to speak • Sensory Aphasia: • loss of ability to understand written or spoken word

  40. TIA • Transient Ischemic Attack • “mini-stroke” • due to temporary restriction of blood flow • symptoms last 5 – 50 minutes • “red flags” that warn impending & more serious CVAs

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