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Neurobiology Test 1
| Question | Answer |
|---|---|
| plasma membrane | cholesterol, proteins, lipids, glycolipids, glycoproteins, cytoskeletal pigments--controls the movement in an out of the cell |
| to pass through the membrane: | must be small, uncharged, and non-polar |
| membrane proteins | transport proteins (channels and carriers), receptor proteins, recognition proteins, and adhesion proteins |
| membrane potential | the electrical difference between cytoplasm and the outside |
| diffusion of molecules | happens randomly and stabilizes at an equilibrium |
| water movement | from hypotonic to hypertonic--from more water to less water |
| hypotonic | hypotonic solution: fewer molecules, more water. Cells become lysed |
| hypertonic | hypertonic solution: more molecules and less water. Cells become shriveled |
| resting membrane potential | the membrane potential at equilibrium |
| receptor potentials | due to external stimuli--light, sound, heat |
| synaptic potentials | transmission of info--one neuron to the other |
| hyperpolarization | increases the separation by making the Em more negative |
| depolarization | lessens the separation of charge by making the Em more positive |
| threshold | the point at which an action potential fires |
| electrical equilibrium | point where ions are balanced |
| equilibrium potential for an ion | assumes full permeability |
| membrane equilibrium potential | takes all ions and permeabilities into account |
| influx | flowing in of ions |
| efflux | flowing out |
| repolarized | when a membrane goes back to its resting membrane potential |
| sodium potassium pump | is an ATPase--uses ATP's energy to change shape and bring K in and dump Na out to maintain balance |
| soma | cell body of a neuron |
| synapse | area where one neuron comes in contact with another |
| dendrites | spikey projections that receive the stimulus from another cell |
| axon hillock | specialized bump of the neuron that connects the axon to the soma |
| axon | the projection of the nerve cell that propagates the action potential |
| synaptic bouton | the fat portion of the neuron that meets at the cleft and gives the signal to the second synapse's dendrites |
| voltage dependent channels | channels that open or close depending on the voltage of the Em |
| Active | uses the sodium potassium pump |
| Voltage clamp technique | uses a membrane and two electrodes--one to inject current, and one to measure current--a reference electrode measures the difference between inside and outside Em--you measure how much is pumped in to figure out how much is coming out |
| inward current | positive ions flowing in |
| outward current | positive ions flowing out |
| tetrodotoxin | blocks Na channels |
| Tetraethylammonium | blocks K channels |
| conductance | the flow of current across a membrane--depends on permeability |
| Na voltage gated channels | open rapidly at threshold--close after 1/2 ms at peak--remain closed for a refractory period |
| K voltage gated channels | open (delayed) at threshold peak--close at low Em during recovery |
| sequence of events for an action potential | 1. Current injected--2. Na opens, positive charge comes in, pushes down membrane--3. K opens, comes in, brings Em down--4. Na close, Em plummets--5. K closes, Em stabilizes |
| Na voltage channel - M and H | M-gate (rapid opening at threshold) H-gate--delayed closing at threshold, closes through descent of action potential |
| K voltage channel - N | N-gate--delayed opening at threshold |
| refractory period | period during which you cannot stimulate a new action potential--limits the number of APs in a row, keeps action potentials moving in one direction |
| Absolute action potential | nothing will fire--absolutely impossible-- (1 ms)--limits action potential firing rate @ 1000ms |
| relative refractory period | overly large signal will fire AP--the K channels are open, so more signal has to be put in to overpower the flow |
| Speed of action potentials | 10-20 m/second is typical; high of 150m/second in some organisms |
| myelin | produced by glial cells of the nervous system; schwann cells in peripheral nervous system, oligodendrocyte in the central nervous system |
| nodes of ranvier | gaps between the myelin that allow for re-initiation of action potential |
| Na concentrations | high outside, low inside |
| K concentrations | high inside, low outside |
| Patch clamp method | penetrate and measure from a single channel by manipulating the membrane |
| down=in | up=out |
Created by:
berge
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