Nervous system

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  • METER STICK DEMO
  • Nervous system

    1. 1. PNS & CNS Neuron Conduction Disease Nervous System
    2. 2. Role of nervous system  To transmit information rapidly  The brain receives information about the environment and responds accordingly
    3. 3. How the nervous system works 1. Detection of stimulus 2. Processing in brain 3. Response in other part of body Fig. 48.1 Sensory neurons Motor neurons
    4. 4. The Basic Nerve Circuit 2. Processing Central Nervous System Brain and Spinal Cord Peripheral Nervous System 1. Sensory Input 3. Motor Output Effector cells Involuntary muscleVoluntary muscle Motor Neurons External Senses Internal Senses Sensory receptors Sensory Neurons
    5. 5. Components of the Nerve Circuit Function Description Components Sensory Input Detect stimulus Sensory receptors Sensory neurons Processing Analyze information Brain & spinal cord (CNS) Motor Output Response in body Motor neurons Effector cells
    6. 6. Peripheral Nervous System (PNS)  Composed of all the neurons that communicate between the body and the central nervous system (brain & spinal cord)  Relays information about environment to the brain  Relays information from brain to body
    7. 7. Organization of the PNS Fig. 48.17 Peripheral Nervous System Effector cells Involuntary System Voluntary System Motor Division External Sensing Internal Sensing Sensory receptors Sensory Division
    8. 8. Types of senses  Sensing the external environment  Somatic senses: skin, muscle, joints  Special senses: vision, hearing, smell, taste, equilibrium  Sensing the internal environment  Visceral senses  e.g. fullness of stomach, blood pressure
    9. 9. Sensory Receptors  Detect a specific type of stimulus Examples Stimuli Location Mechanoreceptors Pressure, movement Skin, muscles, ears Photoreceptors Light Eyes Chemoreceptors Chemicals Nose, mouth Thermoreceptors Temperature Skin Nociceptors Pain Skin
    10. 10. Organization of the PNS Fig. 48.17 Peripheral Nervous System Effector cells Involuntary System Voluntary System Motor Division External Sensing Internal Sensing Sensory receptors Sensory Division
    11. 11. Effector Cells  Carries out body’s response to a stimulus  Voluntary system: responds to stimuli by sending signals to skeletal muscles  Involuntary system: respond to stimuli by sending signals to smooth muscle, cardiac muscle and organs of the body
    12. 12. The Neuron  Nerve: a group of neurons bundled together  Neuron = nerve cell  Neuron: the structural and functional unit of the nervous system  Mature neurons lose ability to undergo cell division http://www.whitney.ufl.edu/images/zacharias-ratYFP-synapse.jpg
    13. 13. Components of a neuron Fig. 48.2a,c
    14. 14. Components of a neuron Component Description Function Cell body Contain nucleus & organelles Carries out basic cell functions Dendrites Multiple short, branched extensions Receives input from other neurons Axon Single long extension Sends information to other neurons
    15. 15. Myelin Sheath  Myelin sheath (lipid) insulates the axon  Analogy: insulation around wires
    16. 16. Myelin Sheath  Only wrapped around axons  not found on other parts of the neuron
    17. 17. Neuron Function  Conducts electrical signals called impulses from one area of the body to another  Electrical impulse is the way neuron communicate information
    18. 18. Direction of impulse conduction Dendrites Cell body Axon Axon terminal Fig. 48.2a
    19. 19. Direction of impulse conduction Electrical impulse is sent from the axon of the transmitting neuron to the dendrite of the receiving neuron
    20. 20. Simplest type of nerve circuit  Reflex: rapid, involuntary responses to stimuli  Processing of the stimulus doesn’t happen in the brain  Processing occurs in the spinal cord  The electrical impulse is sent faster so the body responds automatically without “thinking”
    21. 21. Examples of reflexes http://medicalimages.allrefer.com/large/moro-reflex.jpg https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTT-1Ol3RyXhrbfL1Ijw7e61q7G-NfX__N4ICwOQQQ0QI01CuJ8  Withdrawal (nociceptive) reflex  Knee-jerk (patellar) reflex  Gag (pharyngeal) reflex  Blink (corneal) reflex  Pupillary reflex
    22. 22. Central Nervous System (CNS)  Composed of the brain and spinal cord  Protected by bone: skull and spine  Surrounded by cerebrospinal fluid (CSF):  Shock absorber (cushioning)  Transports chemicals  Removes waste produced in the brain
    23. 23. Spinal Cord
    24. 24. Anatomy of the Brain
    25. 25. Brainstem Fig. 48.20
    26. 26. Brainstem Function  Data conduction  Relay information from higher brain regions  Large-scale coordination  body movement (e.g. walking)
    27. 27. Cerebellum Fig. 48.20 “little cerebrum” Not part of the brainstem
    28. 28. Cerebellum Function  Coordination of movement and balance  Example: hand-eye coordination  Sensory perception:  Receives sensory information about joints, muscles, sight, and sound and relays to motor pathways
    29. 29. Anatomy of the Brain Fig. 48.20
    30. 30. Cerebrum  Most highly evolved structure of mammalian brain  Divided into 2 hemispheres Fig. 48.24a
    31. 31. 4 Lobes of the Cerebrum Frontal Integrate and process information from other lobes Short-term memory Motor cortex: voluntary skeletal movement Temporal Hearing Long-term memory & emotions Parietal Taste & temperature Sensory cortex: touch Occipital Vision Fig. 48.24b
    32. 32. Regions of the Cerebrum Fig. 48.24b
    33. 33. Primary Cortex Fig. 48.25
    34. 34. Primary Cortex  Motor cortex  sends signals to skeletal muscles  Somatosensory cortex  receives and integrates sensory information
    35. 35. Neurological Disorders  Parkinson’s Disease (PD)  Alzheimer’s Disease (AD)  Multiple Sclerosis (MS)
    36. 36. What is Parkinson’s Disease?  A progressive degenerative disorder of the CNS  Recognized by a person’s impaired movement, speech and coordination of the body  Usually begins on one side of the brain and progresses until both sides are affected.
    37. 37. Cause  Certain neurons that produce dopamine die or become impaired.  Dopamine: a chemical in the brainstem that is needed for voluntary movement, attention, learning, cognition, sleep and mood.
    38. 38. Symptoms  Tremor  Muscle rigidity / Stiffness  Slowness of involuntary movements  Poor balance and coordination  Stooped posture
    39. 39. Manifestation  Age of onset: 60 years  Prevalence: 1 in every 100 persons over 60
    40. 40. Treatments  Chronic disorder with no known cure  Main goal of treatments is to control symptoms  Medications are mainly used to increase dopamine levels in the brain  Severe side effects such as hallucination, nausea, vomiting  Living a healthy lifestyle is crucial to managing PD
    41. 41. What is Alzheimer’s Disease?  progressive degenerative brain disease  Neurons deteriorate  Brain atrophy: lose mass  A form of dementia that causes problems with memory, thinking and behaviour
    42. 42. Cause: Plaques and Tangles A plaque is the build up of a protein in the spaces between nerve cells
    43. 43. Cause: Plaques and Tangles A tangle is a twisted strand of protein that build up on nerve cells
    44. 44. Cause: Plaques and Tangles  Plaques and tangles somehow play a critical role in blocking communication among nerve cells and disrupting processes that cells need to survive.  The destruction and death of nerve cells is what causes the problems / symptoms associated with AD
    45. 45. Brain components affected
    46. 46. Brain components affected  Cortex:  Motor skills  Ability to control the five senses  Ability to retain information & solve problems  Hippocampus  formation of new memories (amnesia)
    47. 47. Cortex
    48. 48. Hippocampus
    49. 49. Due to large number of brain cell death, ventricles grow Ventricles
    50. 50. Symptoms  Difficulty forming new memories  Disorientation  mood and behavior changes  deepening confusion about events, time and place  unfounded suspicions about family, friends and professional caregivers
    51. 51. Manifestation  75% are mostly women  Early-Onset Alzheimer’s  under the age of 65  Usually mild conditions  Forgetfulness  Retains the ability to do tasks  Alzheimer’s  above the age of 65  Early symptoms can be mistaken for old age
    52. 52. Treatment  Current medication can not cure AD nor stop it from progressing but can lessens symptoms of memory loss and confusion
    53. 53. What is Multiple Sclerosis?  Neurological disease affecting the CNS  non-contagious  Axons become demyelinated  Lost myelin can be replaced with scar tissue:  can block formation of new myelin  slows down electrical signals (transmission of AP)  Multiple = many, sclerosis = scars  Axons can become withered:  no impulse can be transmitted http://static.howstuffworks.com/gif/multiple-sclerosis-demyelinization.gif
    54. 54. Cause  Idiopathic (no definite cause)  Suspected to be an autoimmune disease  Immune system views myelin sheath as foreign and attacks.  Myelin sheath becomes inflamed and damaged.  Occurs in small patches over the CNS  Other suspected theories  May be triggered by virus or bacteria  May be genetic although MS gene has not yet been found
    55. 55. Symptoms  Unpredictable, affects each person in different ways  Different symptoms  Varying severities  Depends on location of damage  Body functions:  Bladder & bowel problems  Difficulty with swallowing  Slurred speech  Hearing / vision loss  Dizziness, headaches  Muscular:  stiffness / spasms  Numbness / weakness / fatigue  Awkward gait / difficulty walking  Loss of coordination  Uncontrollable tremors  Paralysis  Cognitive:  Mental health problems / depression  Memory problems  Pain, seizures
    56. 56. Symptoms http://upload.wikimedia.org/wikipedia/commons/archive/a/a3/20090203184723!Symptoms_of_multiple_sclerosis.png
    57. 57. Manifestation  Women are 2-3 times more likely to get MS than men.  Affects Caucasians more than other races.
    58. 58. Treatment  Treatment to reduce number of relapses / lessen severity (anti-inflammatory steroids)  Medications to help manage symptoms  Rehabilitation programs  Reducing burden of symptoms:  Flu shot  Avoid stress  Avoid heat  Regular exercise, muscle-stretching exercise

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