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Ch 12: The Central Nervous System

Ch 12: The Central Nervous System. Section 1 – The Brain: A description (p. 430). The Brain: Description. Physical description of the brain : - About 2 fistfuls of pinkish, gray tissue - Wrinkled like a walnut - Consistency of cold oatmeal Size of the brain :

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Ch 12: The Central Nervous System

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  1. Ch 12: The Central Nervous System Section 1 – The Brain: A description (p. 430)

  2. The Brain: Description Physical description of the brain: - About 2 fistfuls of pinkish, gray tissue - Wrinkled like a walnut - Consistency of cold oatmeal Size of the brain: - Mass in average adult male = 3.5lbs - Mass in average adult female = 3.2lbs *In terms of brain mass per body mass, male & female brains are equal…

  3. The Brain: Description The Brain is Divided into 4 Major Regions: - Cerebrum (left & right hemispheres) - Diencephalon - Brainstem - Cerebellum

  4. The Brain: Description Ventricles: - Cavities inside the brain that contain cerebrospinal fluid - Lined with ependymal cells - Connected to hollow tube running up center of spinalcord

  5. Ch 12: The Central Nervous System Section 2 – The Brain: Cerebral Hemispheres (p.433-441)

  6. Cerebral Hemispheres Cerebral Hemispheres: - also known as “cerebrum” - account for about 83% of total brain mass Various surface markings: 1) Gyri– elevated ridges 2) Sulci – shallow grooves 3) Fissures – deep grooves

  7. Cerebral Hemispheres Cerebral Cortex: - thin (2-4mm), superficial layer around the cerebrum Functions of cerebral cortex: - conscious mind awareness - sensory perception - voluntary motor initiation - communication - memory storage - understanding

  8. Cerebral Hemispheres Cerebral Cortex: - each hemisphere concerned with sensory/motor function of oppositeside of body. - no functional area actsalone; conscious behavior involves entirecortex in one way or the other Divided into 4 lobes: - Frontal Lobe, Temporal Lobe, Parietal Lobe, Occipital Lobe

  9. The Brain – Cerebral Cortex Posterior Frontal Lobe: - Site of Primary Motor Cortex (provides conscious control of precise, skilled, voluntary movement of skeletal muscles) - Site of Premotor Cortex (controls learned or repetitious motor skills & coordinates simultaneous/sequential actions) *Damage to primary motor cortex = paralysis of muscles controlled by that area **Damage to premotor cortex = loss of motor skills…muscles still functional, just cannot be controlled correctly Motor Anterior Motor map in precentral gyrus Toes Jaw Primary motor cortex (precentral gyrus) Tongue Swallowing

  10. The Brain – Cerebral Cortex Frontal Lobe: - Site of higher intellectual functions…thinking, etc. - Site of Broca’s area…present in left hemisphere only (motor speech area; directs muscles of tongue) http://www.youtube.com/watch?v=_0aNILW6ILk&feature=related

  11. The Brain – Cerebral Cortex Temporal Lobe: - Site of major memory centers - Site of Primary Auditory Cortex (interprets info from inner ear as pitch, loudness, & location) - Site of Auditory Association Area (language comprehension; stores memories of sounds)

  12. The Brain – Cerebral Cortex Temporal Lobe: - Site of Olfactory Cortex (gives conscious awareness of different odors) - Site of Gustatory Cortex (involved in the perception of taste) - Site of Visceral Sensory Area (provides conscious perception of visceral sensations; for example, upset stomach or full bladder)

  13. The Brain – Cerebral Cortex Posterior Parietal Lobe: - Site of the Primary Somatosensory Cortex (receives & interprets sensory information from skin, skeletal muscles, & joints) - Site of Somatosensory Association Cortex (determines size, texture, & relationship of parts of objects being felt) - Site of Vestibular Cortex (responsible for conscious awareness of balance) Sensory Anterior Sensory map in postcentral gyrus Genitals Primary somato- sensory cortex (postcentral gyrus) Intra- abdominal

  14. The Brain – Cerebral Cortex Occipital Lobe: - Site of the Primary Visual Cortex (receives visual information from the eyes) - Site of Visual Association Area (uses past visual experiences to interpret visual stimuli…color, form, & movement)

  15. The Brain – Cerebral Cortex In general… Left Hemisphere - controls language, math, & logic Right Hemisphere - used for insight, visual-spatial skills, intuition, & artistic skills “Left-brained” people are typically analytical/calculating “Right-brained” people tend to be more artistic/emotional

  16. The Brain – Cerebral Cortex Corpus Callosum: - Nerve tracts that connect right & left hemispheres - Allows for communication between both sides http://www.youtube.com/watch?v=lfGwsAdS9Dc&feature=related

  17. Ch 12: The Central Nervous System Section 3 – The Brain: Diencephalon (p. 441-444)

  18. The Brain – Diencephalon Diencephalon: - Found in center of brain - Encased in cerebrum - 3 subdivisions 1) Thalamus 2) Hypothalamus 3) Epithalamus

  19. The Brain – Diencephalon Thalamus: - Receives all sensory info from body • Redirects info to correct location in brain Hypothalamus: - Site of pituitary gland…master endocrine gland - Helps regulate body temp - Controls metabolism & H2O balance - Emotional response center (perception of fear, pleasure, & rage) - Helps regulate sleep & the sleep cycle

  20. The Brain – Diencephalon Epithalamus: - Forms cerebrospinal fluid - Location of Pineal gland Pineal gland - Secretes melatonin…also helps regulate sleep cycles

  21. Ch 12: The Central Nervous System Section 4 – The Brain: Brain Stem (p. 445-449)

  22. The Brain – Brain Stem Brain Stem: - Attaches brain to spinalcord - Controls automatic behaviors necessary for survival - Consists of Midbrain, Pons, & Medulla oblongata

  23. The Brain – Brain Stem Midbrain: - Located between diencephalon & pons - Contains the Corpora quadrigemina Corpora quadrigemina - Four dome-like protrusions - Visual/auditory reflex centers 1) Superiorcolliculi = Visual reflex center 2) Inferiorcolliculi = Auditory reflex center

  24. The Brain – Brain Stem Pons: - Provides pathway between higher brain centers & spinalcord - Controls normal rhythm of breathing

  25. The Brain – Brain Stem Medulla oblongata: - Attaches brain to spinal cord - Regulates heartrate & bloodpressure - Works w/ pons to regulate rate & depth of breathing - Controls swallowing, hiccuping, coughing, sneezing & vomiting

  26. Ch 12: The Central Nervous System Section 5 – The Brain: Cerebellum (p. 450-451)

  27. The Brain – Cerebellum Cerebellum: - Plays a major role in coordination - Gives you finemotorcontrol - Equilibrium, posture, & motor learning - Plays role in word association & problem solving

  28. Ch 12: The Central Nervous System Section 6 – The Brain: Functional Brain Systems (p. 451-453)

  29. The Brain – Limbic System Limbic System: - area surrounding diencephalon & brain stem - allows us to react emotionally to events - includes basal ganglia, amygdala, & hippocampus

  30. The Brain – Limbic System Basal Ganglia: Amygdala: • Skill learning - Emotion processing - Anger, fear, danger, etc. Hippocampus: - Longterm memories - Damage does not erase memories…prevents new ones from being formed

  31. The Brain – R.A.S. R.A.S.: - reticular activating system - sends impulses to cerebral cortex to keep it conscious/alert - filters out repetitive/weak stimuli to prevent sensory overload - damage to this will lead to coma Parts of the brain…review!! Brain Layers Video

  32. Ch 12: The Central Nervous System Section 7 – The Brain: Higher Mental Functions(p. 453-460)

  33. Higher Mental Functions Electroencephalogram (EEG): - records electrical activity that accompanies brain function Brain Waves: - patterns of electrical activity in the neurons - unique for each individual - used to diagnose & localize brain tumors, epilepsy, sleep disorders, & infections - flat EEG (no waves) indicates no electrical activity & is used to determine “clinical death”

  34. Higher Mental Functions Consciousness: - involves the conscious perception of sensations - have ability to initiate voluntary movements - loss of consciousness is sign that brain function is impaired - defined based on how you behave in response to stimuli 1) Fainting - brief loss of consciousness - caused by loss of blood flow to brain or low BP 2) Coma - total loss of consciousness for long periods of time - incapable of being “woken up”

  35. Higher Mental Functions Sleep: - state of partial unconsciousness; capable of regaining consciousness fairly easily Importance of sleep - considered a period of time where body restores itself - dreams considered a “reverse learning process” where mind is trying to work through daily activities; daily events that have no significant purpose are deleted from memory

  36. Higher Mental Functions Sleep disorders: 1) Narcolepsy - body falls into deepsleep from awake state w/o warning - usually lasts about 15 min 2) Insomnia - chronic inability to obtain amount/quality of sleep needed 3) Sleep apnea - breathing temporarily stops during sleep - often occurs when throat muscles lose tone allowing trachea to become blocked

  37. Higher Mental Functions Memory: - the storage & retrieval of information Two stages 1) Short-term memory (STM) - also called “working memory” - temporary storage of information - limited to 7 or 8 pieces of information 2) Long-term memory (LTM) - limitless capacity - STM information used over & over becomes LTM

  38. Higher Mental Functions Factors that Affect Transfer of STM to LTM: 1) Emotional state - takes place best if alert, motivated, or surprised 2) Rehearsal - repetition & practice promotes transfer 3) Association - tying new information to old memories 4) Automatic memory - some memories stored subconsciously - some events are powerful enough that you don’t have to try to remember them

  39. Ch 12: The Central Nervous System Cranial Nerves

  40. Cranial Nerves There are 12 Cranial Nerves having specialized functions:

  41. Ch 12: The Central Nervous System Section 8 – The Brain: Protection (p. 460-464)

  42. The CNS: Protection Brain & Spinal Cord Physically Protected in 3 Ways: • Bonyarmor • Skull protects the brain • Vertebral column protects the spinalcord • Considered the firstline of defense

  43. The CNS: Protection Brain & Spinal Cord Physically Protected in 3 Ways: • Meninges • 3 layers of connective tissues…wrap brain & spinal cord a) Dura mater - Outermost layer; limits excessive brain movement b) Arachnoid mater - Middle layer; weblike c) Piamater - Inner layer; very delicate; highly vascularized WARNING!!! Some fairly graphic pictures ahead…

  44. The CNS: Protection Brain & Spinal Cord Physically Protected in 3 Ways: • Blood-brain barrier • Capillaries of brain unlike those in rest of body…resistdiffusion of substances other than O2 & CO2 • Other substances that can get through…alcohol, nicotine, & anesthesia

  45. The CNS: Protection Cerebrospinal fluid (CSF): - fluid between meningeal layers that provides cushioning - also nourishesthe brain & spinal cord

  46. Ch 12: The Central Nervous System Section 9 – The Brain: Homeostatic Imbalances (p. 451-453)

  47. Homeostatic Imbalances of the Brain Traumatic Brain Injuries: - Leading cause of accidental death • Concussion • Slight brain injury…no permanentdamage • Contusion • Bruising of brain tissue…blood destroys tissue • Permanent damage…tissue does not regenerate • Cerebraledema • Swelling of brain tissue • May compress brain & cause death of tissue

  48. Homeostatic Imbalances of the Brain Cerebrovascular Accident (CVA): - More commonly called a stroke - Result of blocked blood vessel in brain - Brain tissue that is supplied with O2 from that blood vessel will die - Leads to loss of function or possible death Aneurysm: - Blood vessel bursts in the brain

  49. Homeostatic Imbalances of the Brain Alzheimer’s Disease: - Progressive, degenerative brain disease - Mostly seen in elderly…usually begins in middle age - Causes structuralchanges in the brain…abnormal proteindeposits & twisted neurons - Memory loss, irritability, confusion, hallucinations, death

  50. Homeostatic Imbalances of the Brain Hypersomnia: - condition where individuals sleep as much as 15hrs/day Microcephaly: - formation of a small brain - most children with this will experience mentalretardation Hydrocephalus: - build-up of CSF due to some kind of obstruction - skull becomes noticeably enlarged due to increased fluid pressure & incomplete fusion of skull bones

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