Term
| Nervous System (primary division) |
|
Definition
central nervous system: brain, spinal chord, retina
peripheral nervous system: cranial and spinal nerves |
|
|
Term
|
Definition
| Nerve is a bundle of axons, neuron is a functional unit |
|
|
Term
|
Definition
Dendrites (input): receives signals, integrates signals
axons and terminal (output): conduct and transmit, 1mm -> 1m long |
|
|
Term
|
Definition
electrical signaling: sent from axon hillock -> axon ->terminal
electrically excitable
neurons, muscle (skeletal + cardiac), and B pancreatic cells |
|
|
Term
|
Definition
Increases speed of signal by up to 150 m/s
CNS - Oligodendrocyte: 1 cell = multiple segments
PNS - Schwann Cell: 1 cell = one segment |
|
|
Term
| Increase speed of a signal |
|
Definition
| Myelination ( ^ up to 150 m/s) or increase the diameter of an axon ( ^ up to 10 m/s) |
|
|
Term
| White and Grey matter of Brain |
|
Definition
grey matter: cell dodies, dendrites, axons, glia, and capillaries
white matter: myelinated axons
In general the brain is grey on the outside with white matter on the inside. The spinal chord is white on the outside with grey matter on the inside |
|
|
Term
|
Definition
C Golgi (Golgi staining): stains 1% of cell randomly. Shows that neurons are singular entities
S.R Cajal: Golgi created process, but Cajal formulated the concept! (Golgi actually believed nervous system was a susoltion) |
|
|
Term
|
Definition
tag a specific protein via an epitope (3 unit section) with a primary protein antibody (specific) and then tag the primary protein antibody with a general florescent secondary antibody.
Cell must be fixed in order for this to work i.e. cell is dead |
|
|
Term
| Green Fluorescent Protein (GFP) |
|
Definition
GFP can be added to the end of your favorite protein and can be visualized in live cells.
Can be used on live cells!
Negative: # of choices are limited, changes protein properties |
|
|
Term
|
Definition
| fMRI can detect change in metabolism (sugar) or blood flow. You can see activity in the brain |
|
|
Term
|
Definition
support and modulate function of neurons
In the CNS there are microglia, oligodendrocytes, and astrocytes |
|
|
Term
|
Definition
Type of Glia (CNS)
come from bone marrow, residential |
|
|
Term
| Oligodendrocytes + Schwann Cells |
|
Definition
Type of Glia (CNS)
Myelin: function is to insulate and speed up electrical conduction by axons
Rich in cholesterol and phospholipids
Schwanna cells have positive role in regeneration |
|
|
Term
|
Definition
Type of Glia (CNS)
as the complexity of the nervous system increases, so does the size of the astrocyte as well as the # of astrocytes per neuron
Essential to the Blood Brain Barrier. Prevents diffusion (very specific as to what it allows in the brain)
Removes glutamate and GABA
Synthesizes precursors of Glutamate (Glutamine) and GABA
Provides energy to neurons
Secretes: Glial Derived Neurotrophic Factor (GDNF) which promotes survival of cell, as well as TNF, which promotes apoptosis of cell (death)
Emerging Functions: Regulate synaptogenesis, regulate neurogenesis, modulate synaptic strength |
|
|
Term
|
Definition
| Glial Scars occur after there has been an injury to the CNS. They are benificial in that they repair the blood brain barrier, but detrimental in that they inhibit regeneration. |
|
|
Term
| Glial and Nerve Regeneration |
|
Definition
CNS (axon regeneration poor) - Oligodendrocytes secrete inhibitors, astrocytes secrete inhibitors and create a glial scar (physical barrier)
PNS: Schwann cells have a positive role in regeneration |
|
|
Term
| Four Steps of Electrical Signaling |
|
Definition
1. Local passive response: receptor potentials (sensory neurons), synaptic inputs
2. Integration: Signals integrate in dendrites and cell body
3. Active Response: action potential propogatin
4. Signaling between neurons: Synaptic transmission |
|
|
Term
| Establishing Concentration Gradients |
|
Definition
ATPase Pumps use ATP to move ions up gradient
ex: Na+/K+ pump - active transport |
|
|
Term
| General Ionic Distribution |
|
Definition
| High K+ within cell, High Na+, Cl-, Ca2+ outside of cell |
|
|
Term
|
Definition
all cells have resting potentials
all cells have similar ionic concentration
all cells contain K+ and Cl- leak channels and have negative resting potential
Influenced most by K+, therefore you can conclude that K+ channels are open at rest and that membrane potential is near K+ equilibrium potential |
|
|
Term
|
Definition
| Resting potential is primarily K+, action potential is primarily Na+ |
|
|
Term
|
Definition
| [Na+] only changes 0.001 (1%) between resting potential and action potential. Concentration maintained via Na+/K+ pumps |
|
|
Term
|
Definition
Myo (muscle) -tonos (tension)
mutation of the Cl- channel in skeletal muscle
defecting resting potential
prolonged muscle contraction (multiple AP) |
|
|
Term
| GABA in developing vs. mature neuron |
|
Definition
GABA - gamma aminobutyric acid -> opens Cl- channel
Developing Neuron: GABA = depolarization
[Cl-] in cell=25mM, [Cl-] outside of cell=150mM
Ecl = -45 mV
Mature Neuron: GABA = hyperpolarization
[Cl-] in cell=7mM, [Cl-] outside of cell=150mM
Ecl = -77 mV |
|
|
Term
|
Definition
Goal: control membrane potential and measure ionic currents (not elicit action potential
Determines: which types of ions are open/closed, when open, and how they respond to V
Demonstrates that Na+ has rapid activation -> inactivation, K+ slowly opens |
|
|
Term
|
Definition
Current (I) +, then V is > Eeq, and current flows out
Current (I) -, then V is < Eeq, and current flows in |
|
|
Term
| Two methods to separate currents |
|
Definition
Make 1[ion]o = [ion]i
or
use channel blockers: TEA and TTX |
|
|
Term
|
Definition
TEA: tetraethyl ammonium - blocks K+ channels
TTX: tetratoxin - blocks Na+ channels |
|
|
Term
|
Definition
Na+ has two channel gates, activation gate ("m") and inactivation gate ("h")
K+ has one activation gate ("n") and K+ leak channels that are always open -> resting potential |
|
|
Term
|
Definition
Temporal summation = signals summed over time
Spatial summation = signals simultaneously occurring (and summed)
Response decreases over distance because of resistance: high internal resistance and low membrane resistance |
|
|
Term
|
Definition
| Terms: Juxtaparanoe, Paranode, Node of Ranvier |
|
|
Term
|
Definition
Na+ influx overcoming K+ efflux
Not fixed voltage - dependent on recent history of # of ions and what type |
|
|
Term
|
Definition
| decreased excitability of AP |
|
|
Term
| AP Afterhyperpolarization |
|
Definition
| Very close to the equilibrium potential Ek of K+. Many K+ channels are open at this point |
|
|
Term
|
Definition
| is determined by the rates of channels opening and closing, not the concentrations of particular ions or the equilibrium potentials |
|
|
Term
| Why does Na conductance fall more rapidly than its activation gates close |
|
Definition
| Na+ channels are controlled by both activation (m) and inactivation (h) gates. The inactivation gates close before the activation gates do, and are impermeable to Na. Therefore, the activation gates can still be open, but no Na can pass. |
|
|
Term
| How can axons fire a second action potential (Na gates) |
|
Definition
| after the membrane re-polarizes to the resting potential, and the "h" gates have enough time to reopen, a second AP can be fired |
|
|
Term
|
Definition
The time after an Action potential when the generation of a second action potential is difficult or impossible.
relative and absolute refractory periods
absolute refractory period approx. 7 msec
relative refractory period approx. 18 msec
Prevents AP from propagating backwards |
|
|
Term
| What mechanisms might a cell use to alter its electrical excitability? |
|
Definition
it can alter the relative concentrations of ions. For example, it will be easier to fire an AP when K+ channels are closed, and Na "h" gates are open. It will be harder when more K and Cl channels are open, and Na is inactivated.
effected by the recent electrical history of the cell. i.e. how long after last AP
More Excitable (fire repeatedly): close K+ channels, open Na+ channels
Less Excitable (more stable resting pot): open K+ channels and Cl- channels |
|
|
Term
| How is the blood brain barrier formed |
|
Definition
| formed by tight junctions between endothelial cells. astrocytes are required for the induction and maintenance of these junctions |
|
|
Term
| Functions of the Blood Brain Barrier |
|
Definition
| prevents entry of many common pathogens to the CNS. Helps maintain the homeostasis of the CNS |
|
|
Term
| Negative Impacts of the Blood Brain Barrier |
|
Definition
antibodies and white blood cells cannot enter the CNS, so they cannot fight harmful pathogens.
BBB also limits the delivery of therapeutic agents and drugs |
|
|
Term
| Transport through the Blood brain Barrier (Glucose/ Gas) |
|
Definition
The BBB restricts entry of all large hydrophilic molecules to the CNS. In order for a hydrophilic molecule such as glucose to enter, it must be actively transported.
Gasses such as oxygen are small and hydrophobic, and can easily diffuse across the lipid bilayer. |
|
|
Term
|
Definition
Driving force = V - E equil
I = G (V - E equil)
G- estimate whether the gate will be open or closed
Determines direction of ion movement (either out or in): out is positive, inward is negative |
|
|
Term
| Relative speed of channels |
|
Definition
| Na+ channels are fast, K+ channels are slow |
|
|
Term
| Prevailing view of CNS in 19th century |
|
Definition
| The CNS was a "Syncytium" or a large cell like structure filled with cytoplasms and neurons |
|
|
Term
|
Definition
| Dendrites, Cell body, axon, and nucleus |
|
|
Term
| How are Na ions prevented from passing through K+ channels |
|
Definition
The strong interactions between the selectivity filter and the helix would not collapse due to the small
size of the sodium ion. sodium is too small for optimum interaction |
|
|
Term
| Voltage Gated K+ channels in myelinated axons are located in what region |
|
Definition
|
|
Term
| The "voltage sensor" on a voltage gated Na channel |
|
Definition
| The highly conserved S4 region of the a-subunit of the Sodium voltage gates 6 unit structure. Conformation change due to voltage sensitive, positively charged amino acids. |
|
|
Term
| Selectivity filter of Na channels |
|
Definition
| selectivity filter in the pore of voltage gated Na channels made of negatively charged amino acids (blocks Cl-) Pore is just large enough to fit Na |
|
|
Term
| standard unit of conductance is |
|
Definition
|
|
Term
| conduction of an action potential in a myelinated axon (term) |
|
Definition
|
|
Term
| Types of Voltage Clamp Recording |
|
Definition
Whole Cell recording - chunk of wall removed, strong suction, cell wall continuous with recorder
Inside out recording - intracellular portion of cell wall exposed to air
Outside in recording - extracellular portion of cell wall exposed to air |
|
|
Term
| What causes Long Q-T syndrome |
|
Definition
| Na channels that fail to inactivate and K channels that are less active |
|
|
