Nervous System

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Nervous System
2011-01-28 18:25:45
Nervous System BIO

Nervous System BIO 203
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  1. Internal Coordination Maintenance
    • Monitors internal and external environment
    • Determines appropriate responses
    • Sends signals muscles and glands to respond
  2. Central Nervous System
    Brain and Spinal Cord
  3. Peripheral Nervous System
    Nerves throughout the body that carry input to/from the brain and spinal cord
  4. Sensory Division in Peripheral Nervous System
    Carries information from sense organs to Central Nervous System
  5. Motor Division in Peripheral Nervous System
    Sends information from central nervous system to muscles and glands
  6. Somatic Nervous System
    Carries information to skeletal muscles
  7. Autonomic Nervous System
    Carries information to glands, cardiac muscles, and smooth muscle
  8. Sympathetic Nervous System
    fight or flight in autonomic nervous system
  9. Parasympathetic Nervous System
    Rest and digest in autonomic nervous system
  10. Neurons
    Excitable, conduct electrical signals, communicate with other neurons through chemical means, and typically has cell body (soma), dendrites, axon
  11. Glia
    Not usually excitable, maintains homeostasis, support neurons, and form myelin.
  12. Cell Body (Soma)
    Includes nucleus and most other organelles; integrates all incoming info
  13. Dendrites
    Receive signals from other neurons or environments
  14. Axon
    Conducts electrical signal
  15. Axon Terminal
    Releases chemical signal (neurotransmitter) to communicate with other neurons, muscles, or glands
  16. Microglia
    Protect neurons by scavenging infections agents, damaged neurons, etc
  17. Astrocytes
    Anchor neurons to their blood supply; scavenge excess ions; recycle neurotransmitters; convert glucose to lactate to feed neurons
  18. Oligodendrocytes/Schwann Cells
    Wrap around axons to form myelin
  19. Ependymal Cells
    Line ventricles of brain and produce cerebospinal fluid
  20. Electrical Potential in Neurons
    • Uneven distribution of ions across plasma membrane because of phospholipid bilayer
    • Membrane potential is usually around -70 mV (compared to ~1.5 V in AAA battery); negative indicates that the inside of the cell has more negative charge that the extracellular fluid
  21. Resting Membrane Potential
    • Some ions can leak across the membrane through channels
    • But the Na+/K+ pump pumps Na+ back out and K* back in
  22. Incoming Information Can Alter Membrane Potential of Dendrites
    • Neurotransmitter binds to Na+ channel and opens it
    • This might take membrane from -70 mV to -50 mV
  23. Action Potential
    • When the voltage changes, it can spread to axon and trigger action potential (conduction of electrical signal down axon)
    • The action potential is merely a sequence of the opening and closing of several types of ion channels that repeats down the axon
  24. Axon Hillock
    Where the action potential begins
  25. Myelin
    Oligodendrocytes in CNS and Schwann cells in PNS wrap around dendrite to insulate them
  26. Function of Myelin
    • Myelin allows action potential to travel faster
    • Loss of myelin causes one of several diseases (including multiple sclerosis)
  27. Acetylcholine
    Released by motor neurons
  28. Amino Acids
    • Glutamate: excitatory neurotransmitter
    • GABA: inhibitory neurotransmitter
  29. Monoamines
    • Dopamine: reward, movement
    • Norepinephrine: attention, sympathetic NS
    • Serotonin: mood, apetite, sleep, memory, intestinal contractions
  30. Neuropeptides
    • Substance P: Pain
    • Endorphins: analgesia and addiction
    • Neuropeptide Y: hunger
  31. Depolarization
    Some activated receptors (like glutamate receptors) bring membrane potential closer to action potential threshold (called depolarization of excitatory postsynaptic potential)
  32. Hyperpolarization (IPSP)
    Some activated receptors (like GABA receptors bring membrane potential farther from action potential threshold (called hyperpolarization or inhibitory postsynaptic potential)
  33. Too Much Neurotransmitter Problems
    Epilepsy, traumatic brain injury, huntington's disease, AIDS dementia complex, neuropathic pain, parkinson's disease, ALS, Rett syndrome, Alzheimer's, Tourettes, drug addictions, multiple sclerosis, depression, glaucoma
  34. Too Little Neurotransmitter Problems
    Parkinson's, Depression, anxiety, obesity, anorexia, bulimia, chronic pain, migraines, ADHD, restless leg syndrome, alzheimer's
  35. Neurotransmitter Release is Tightly Regulated
    • Some diffuses away from synapse
    • Some are broken down by enzymes in synapse (MAO, COMT)
    • Some taken back up into presynaptic cell to be recycled
  36. Integration
    In reality, most neurons receive input from tons of presynaptic neurons