Neurons & Nervous system

  1. Most of the cells in the body are ______ charged. state an example
    • negatively 
    • neurons
  2. _____ & _____ can drastically change their voltage
    Neurons & muscles
  3. ____ cells are not excitable and their job is to support neurons/ maintain extracellular environment
    Glial cells
  4. If the cell is not symmetrical, we call it _____
  5. Cells communicate with dendrites and axon terminals. Dendrites _____ neurotransmitters while axons terminals ______ neurotransmitters
    • receive
    • release
  6. We name our neurons by what they ______.
    Name the type of neuron if its neurotransmitter is:
    • release
    • glutamatergic
    • dopaminergic 
    • seratonergic 
    • noradrenergic
    • cholinergic
  7. Neurons can _____ a lot a of different types of neurotransmitters but can only _____ one type.
    • receive
    • release
  8. Nerves: 
    • bundle of axons from diff. neurons in PNS 
    • bundle of axons from diff. neurons in CNS
  9. Clusters of cell bodies in the brain are called _____.  Clusters of cell bodies in the PNS are called _____.
    • nuclei
    • ganglia
  10. Two types of synapses are ______ & _____.
    chemical & electrical synapses
  11. Chemical synapses do not touch each other due to the presence of a _____ ______
    synaptic cleft
  12. electrical synapses connect to each other via ____ ____
    gap junctions
  13. Electrical synapses spread _______ and are found in places that require ____ _____
    • action potentials
    • quick reflexes
  14. Purkinje cell (3)
    • takes input from 1000s of neurons
    • integrates info
    • makes a decision
  15. Bipolar cell is the only neuron in the body that can't?
    fire an action potential
  16. _____ ____ is the site where we receive transmitter
    dendritic spine
  17. Excitatory transmission tends to be near the ______. Inhibitory transmission tends to be near the _____
    • Dendrites
    • soma
  18. Postsynaptic densities are _____ rich
  19. Presynaptic/ axon terminal side always the side with _____ filled with one type of _____
    • vesicles
    • transmitter
  20. Axon terminal will bind to receptors, _____ _____ ion channels, and the info from transmitter will be transmitted to the _____ ____
    • ligand gated ion channels
    • postsynaptic spine
  21. The three expected members of the chemical synapse
    • presynaptic terminal
    • postsynaptic terminal 
    • glial cell
  22. If we want cell, like heart muscles cells, to fire uniformly,  we have to connect them via ____ _____
    gap junctions
  23. Neurons in the brain want to fire action potentials which start at the _____ ____
    axon hillock
  24. Blood brain barrier
    continuous capillaries, even the glial cells are wrapped in capillaries for extra reinforcement. Only O2 in and CO2 out
  25. Oligodendrocytes myelinate axons in the ____ and schwann cells myelinate axons in the ____
    • CNS
    • PNS
  26. The electrical flow that myelin insulates is basically formed by ____ _____.
    ion movement
  27. Ligand gated ion channel's proteins will be expressed at _______ at chemical synapse. When the neurotransmitter binds, the ligand gated ion channel open up and ions diffuse across their _______ ______
    • dendrites
    • electrochemical gradient
  28. After positive volgate gated ion channels open, what two things determine ion movement?
    • permeability 
    • electrochemical gradient
  29. Where are voltage gated channels expressed
    from the axon hillock all the way to the axon terminal
  30. We measure voltage by comparing
    charge inside the cell to outside
  31. Resting membrane
    when the neuron is not experiencing any info, nothing is communicating with it.
  32. Membrane potential
    The momentary potential
  33. EPSPs & IPSPs are due to ____ ____ ion channels and occur at the _____
    • ligand gated ion channels
    • dendrites
  34. Glutamate is likely to release ___ and glycine and GABA are likely to release ___
    • Na+
    • Cl-
  35. Three reasons why neurons are negative
    • The Na+/K+ pumps are electronegative (net negative of -1)
    • Inside the cell we have a lot of negatively charged particles like DNA, most proteins etc, they contribute to net negativity
    • We have more K+ leak channels than we have Na++
  36. Nerst potentials for K+, Na+, Ca++, Cl-
    around -90V for K+, +56 for Na+, +40 for Ca++ & -60 for Cl-
  37. We are much more permeable at rest to ___ than we are to ___. Because we express more ___ leak channels than ___ leak channels
    • K+
    • Na+
    • K+ leak channels
    • Na+ leak channels
  38. calculating driving force
    Voltage of the cell minus the equilibrium potential for the ion (Vm is membrane potential & Eion is equilibrium potential)
  39. If we have a massive driving and zero permeability, _____ _____ ____ occurs. If there is no driving force but massive permeability, current will be ______. We must know both to determine _____ ____. With a huge driving force however, we will be able to determine that there is a ______ for a current flow.
    • minimal current flow
    • minimal
    • current flow
    • potential
  40. Action potential resting state (REVIEW):
    Resting state (9)
    • All voltage gated ion channels are closed, along with the ligand gated ion channels. Only thing open are leak channels
    • There is an activation gate and an inactivation gate on Na+ and K+ only has an activation gate
    • Activation gates are closed and the inactivation gate is open (when either of the gates are closed, ionic motion is halted
    • IF the cell is negative, the Na+ & K+ activation gates are closed. IF the cell is positive they Na+ & K+ are open.
    • Na+ activation gates open/close quickly
    • K+ activation gates open/close slowly
    • If the cell is negative, both the Na+ & K+ inactivation gates will open and if it is positive, it will close
    • Both inactivation gates are very slow
    • Changes will occur in the gates when we become more (+) than threshold (-55) not more (-)
  41. Action potential story:
    Threshold (6)
    • We get to threshold with EPSPs at the dendrites and it'll lead to action potentials at the axon hillock
    • At -50 Na+ activation gates open up fast and first
    • Na+'s driving force would be around -120
    • Na+ ions will want to enter, the permeability will also increase drastically (near equilibrium potential for Na+)
    • Na+ is trying to make the neuron hit its equilibrium potential
    • K+ can't do much about it, its only source of influence at the moment are the leak channels
  42. Action potential story:
    action potential (8)
    • At the peak of the action potential, inactivation gates close
    • Permeability for Na+ goes down to zero
    • Activation gate is still open because the cell is still positive
    • Activation gate for K+ finally opens. The membrane potential (+30) minus the equilibrium potential (-90). This gives us a membrane potential of +120 inside the cell
    • So Na+ will be forced out to make the inside more (-)
    • K+ is trying to make the cell its own equilibrium potential
    • At this point, the only channels open (repolarization/hyperpolarization) Leak K+ channels & Voltage gated K+ channels
    • This will make the cell really (-) so eventually the activation gate for K+ channels will have to close and the inactivation gate will reopen, leaving the only other open channel being the K+ leak channel
  43. Action potential story
    Resting potential
    • We get back to resting potential with the K+ leak channel, NOT the Na+/K+ pump
    • Rest will be perturbed by ligand gated ion channels at the dendrites
    • Dendrites will have ionic flow called EPSPs and IPSPs
    • The only thing that influences opening and closing is voltage, unless it’s a leak channel
  44. 3 reasons we can't fire action potentials during refractory period
    • Reason 1: K+ channel is still open, so we have a K+ leaving for every Na+ that enters
    • Reason 2: Na+ Inactivation gate is closed, so the orientation will not allow it. (absolute refractory period)
    • Reason 3: At relative refractory period, we can fire another action potential but it'll be very hard. It is possible because some of our Na+ inactivation gates have opened
  45. Axons communicate by _______ of different regions at different times sending _____ moving. The purpose of all of this is to get the ______ ______ to +20mV, allowing ____ to come in and binds to the synaptic vesicle causing _____ _____
    • depolarization
    • voltages
    • axon terminal 
    • Ca++
    • vesicular exocytosis
  46. Thought experiment: What if we blocked the voltage gated K+ channels, what will the equilibrium potentials and action potentials look like? (6)
    • At rest the only channels open are leak channels
    • The voltage gated Na+ channels will open and head towards the Na+ equilibrium potential
    • Action potential's peak will not be any different
    • Inactivation gate will close
    • Repolarization will stall or take a very long time without K+ voltage gated channels. The only repolarization will be through the very few K+ leak channels.
    • There will also be no hyperpolarization, keep in mind it is due to the extra permeability of K+ from the K+ voltage gated channels
  47. Thought experiment: What if we modified the amino acid sequence of the Na+ inactivation gate so it closes 200ms more swiftly (4)
    • At rest the only channels open are leak channels
    • The voltage gated Na+ channels will open and head toward the Na+ equilibrium potential
    • Action potential's peak will be shorter because we are stopping the permeability of Na+ more quickly than usual
    • Everything else would be normal
    • *if we cut it off faster and faster we may get to a point that all we get are EPSPs without action potential
  48. Nicotinic receptors are found in ____ muscle and the _____. They are _______
    • skeletal
    • brain
    • ionotropic
  49. Ligand gated ion channels is found at _____. Neural transmission occurs at the ____, Voltage gated Na+ & K+ channels at the ____ _____
    • dendrites
    • soma
    • axon hillock -axon terminal
  50. _____ ____ is the region we are attempting to get to threshold -45mV to eventually get to action potential.
    axon terminal
Card Set
Neurons & Nervous system
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