AN SC 310 - 5

Card Set Information

AN SC 310 - 5
2012-10-04 02:08:47
AN SC 310

Lecture 5 - The Resting Membrane Potential
Show Answers:

  1. The Nervous System is split into 2 parts, what are they?
    • Central Nervous System (CNS)
    • Peripheral Nervous System (PNS)
  2. What body parts are included in the Central Nervous System (CNS)?
    • Brains
    • Spinal Cord
  3. What is the input and the output of the Peripheral Nervous System (PNS) called?
    • Input - Afferent Information
    • Output - Efferent Information
  4. What senses are part of afferent information?
    • Somatic senses
    • Special senses
    • Visceral senses
  5. What are the 2 types of efferent information?
    • Somatic - voluntary
    • Autonomic - involuntary
  6. What are the 2 categories of the autonomic PNS?
    • Sympathetic
    • Para-sympathetic
  7. Whatpart of the PNS is responsible for Fight or Flight?
  8. What are the cells of the Nervous System?
    • Neurons (10%)
    • Glial Cells (90%)
  9. What is the role of Neurons?
    • Excitable cells
    • Functional units of CNS
    • Transmit electrical impulses/signals

    Electrical Signals = Action Potentials
  10. What are the components of Neurons?
    Soma - nucleus, organelles

    Dendrites - receive info from other neurons

    • Axon - transmit action potentials
    • - Axon Hillock - axon origin, where action potentials initiated
    • - Axon Terminal - releases neurotransmitters
  11. Define Synapse
    Site of communication between two neurons or between a neuron and an effector organ
  12. What are the properties of leak channels in neurons?
    • Always open
    • Ion movement based on the concentration gradient
    • Throughout the neuron
    • Maintain resting membrane potential
  13. What are the properties of ligand-gated channels in neurons?
    • Open or closed in response to ligand binding
    • Ion movement down concentration gradient
    • Located on dendrites and cell body
    • Synaptic potentials
  14. What are the properties of voltage-gate channels?
    Open/close in response to change in Vm

    • 2 types:
    • Na+/K+ channels
    • Calcium channels
  15. Where are Na+/K+ channels located and what do they maintain?
    • Throughout, more in axon (hillock)
    • Action Potentials
  16. Where are calcium channels located and what do they maintain?
    • Axon terminal
    • Release of neurotransmitter
  17. What are the structural classes of neurons?
    • Bipolar
    • Pseudo-unipolar
    • Multipolar
  18. What are the functional classes of neurons?
    • Afferent neurons
    • Efferent neurons
    • Interneurons
  19. What is the structural organization of neurons? Lowest level to highest level.
    Nuclei < Pathways and tracts < Commissures < Ganglia < Nerves
  20. What are the different types of glial cells?
    • Astrocytes (star-shaped cells)
    • Ependymal Cells
    • Microglia
    • Oligodendrocytes
    • Schwann Cells
  21. What are properties of Oligodendrocytes?
    • CNS
    • 1 oligodendrocyte forms several myelin sheaths which myelinate sections of several axons
  22. What are properties of Schwann Cells?
    • PNS
    • 1 Schwann Cell forms one myelin sheath which myelinates one section of an axon
  23. What is the resting membrane potential (in mV) and why does it exist?
    • ~ -70 mV
    • More negative charges inside cell and more positive charges outside cell
  24. What 2 factors are critical in determining resting membrane potential?
    • Ion concentration gradients
    • Membrane permeability to these ions - ion channels
  25. What percent of the RMP is directly due to the Na/K-ATPase and why? ...indirectly?
    20% - 3 Na+ out, 2 K+ in: net 1+ out

    80% - Produces concentration gradient: Na high outside, K high inside
  26. How is K+ equilibrium potential reached?
    • K+ diffuses out of the cell (chemical force out)
    • Inside of cell becomes more negative
    • K+ is pulled back into the cell (electrical force in)
    • Elec/Chem forces eventually equal eachother at -94 mV
  27. How is Na+ equilibrium potential reached?
    • Na+ diffuses into the cell (chemical force in)
    • Inside of cell becomes less negative
    • Na+ is pushed out of cell (electrical force out)
    • Elec/Chem forces eventually equal eachother at +60 mV
  28. What is the difference in K+ and Na+ permeability in a typical neuron?
    Membrane is 25x more permeable to K+
  29. How are the ions distributed inside/outside a neuron cell?
    • Inside: K+, organic anions
    • Outside: Na+, Cl-
  30. Describe the process of establishing a resting membrane potential.
    • Chemical driving forces - K+ out, Na+ in
    • Membrane more permeable to K+
    • More K+ leave cell than Na+ enters
    • Inside of cell becomes more negative
    • Electrical forces develop - Na+ in, K+ in
    • K+ outflow slows, Na+ inflow speeds
    • Steady state develops - Na+ inflow = K+ outflow
    • RMP of a neuron = -70 mV
  31. What maintains the RMP?
    Sodium pump
  32. How do Na+ and K+ move in/out of a neuron at rest?
    • Small Na+ leak (high force, low permeability)
    • Small K+ leak (low force, high permeability)
    • Sodium pump returns Na+ & K+ to maintain gradients