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26 Cards in this Set
- Front
- Back
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Cerebellum
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motor movement
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Brain stem
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homeostatic function
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Dentrites
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receive
little bumps "spines": areas where synaptic signals are recieved |
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Axon
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send
axon hillock- action potentials are generated here axon terminals- at synapse, message is sent to the next cell |
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Polarization
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signal spreads from dendrites to cell body to axon hillock to axon terminals
exception: Retinal Horizontal Cells -sometimes have axons, sometimes not. -even when present, axon does not conduct spikes but actually acts to keep two end of the cell isolated from one another -both dendrites and axons receive and send signals Retinal Amacrine Cells: -never have axons sometimes the dendrites conduct action potentials -dendrites both receive and send signals at synapses |
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synapse
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areas of signal spread from axon terminals to dentrites
they are specialized areas of contact bw cells that can be easily recognized in the electron microscope. |
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Cerebral Cortex
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has pyramidal cells
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3 examples of polarized neurons:
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pyramidal cell from cerebral cortex
purkinje cell from cerebellum stellate cell from cerebral cortex |
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Glial Cell
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type of schwann cell that produces myelin, sheathing the axons of peripheral neurons (around axons going from spinal cord to muscle)
in pns, shwann cell makes sheath in cns, oligodentrocyte makes sheath -surround neurons, seem to produce protective enviroment -they are tiny dendrites astrocytes: look like starts. -have endfeet that put cells into direct contact with capillaries of circulatory system and neurons. -thought to serve a nutritive function |
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Molecules of the nervous system:
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pumps/transporters
-Na/K ATPase -Ca ATPase (both use membrane proteins and energy of terminal phosphate of ATP to move ions across membrane) Channels -voltage-gated channels (Na) -ligand-gated channels (glutamate receptors) -second-messenger gated channels (all channels create a change in voltage responsible for cell communication) Metaboropic (heptahelicial) receptors |
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Na/K ATPase pump
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integral protein: alpha subunit does most of the work. Beta subunit helps the protein to fold
the affinity of the binding sites for Na and K change as enzyme is phosphorylated. ATP phosphorylates -puts a phosphate directly onto an amino acid on the cytoplasmic side of the protein -drives a conformational change and changes the affinity -change in ion affinity and change in conformation moves the ions across the membrane E1 protein conformation has Na affinity E2 has no Na affinity so they are dropped and move across. it has high K affinity so they bind |
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Driving Force
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pumping of ions across the membrane produces differences in concentrations for ions
Na higher outside cell, K higher inside cell this creates a potential for a concentration gradient because there is too much Na outside and K inside. Difference produces a voltage called the RESTING POTENTIAL. |
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Typical Volatage Gated Channel
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K+ channel
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Typical Ligand Gated Channel
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acetylcholine receptor
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Second Messenger Gated Channels
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similar in structure to voltage gated channels
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Unstimulated Resting Potential
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-70 mV
opening and closing of channels produces a flow of ions into or out of cell flow of ions makes a change in membrane potential changes in membrane potential are responsible for communicating information from one cell to antoehr |
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The inside of the cell is more _______ (negative or positive) than the outside.
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negative by -60 mV
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Resting Membrane Potential- membrane is selectively permeable to K+
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K+ ions move selectively out of the cell
causes voltage across membrane to change, inside (cytoplasm) becomes more negative As it gets more (-), K+ stops moving out of cell. Resting pot stabalizes it's being pushed by diffusion but pulled back by charge of cell. this is what creates the resting potential |
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Nernst Equation
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Ek=(RT)/(zF) x ln (K+)out/(K+)in
gives the membrane potential across a membrane that is effectively permeable to a single ion type such as K+ or Na+ answer produced is the number of ions that have to move. this number is very small (it doesn't take much to change the voltage). |
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If the membrane were permeable to K+, the resting potential of most neurons is______
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-70 mV
this is less negative than the value from the Nernst eq. because nerve cells realistically also have some permeability to Na+ the resting potential is intermediate between the value it would have if the membrane were permeable only to K+ or only to Na+ but is much close tot the value predicted for K+ |
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Hyperpolarization
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negative change in membrane potential
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Depolarization
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membrane potential becomes more postive
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What happens when you open the ion channel?
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produced a flow of Na+ ions into the cell
increases # of + ions inside cell, produces a positive going change in membrane potential (depolarization) (meanwhile the K+ channels are always open because those are responsible for the resting membrane potential) |
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Conformational Change
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when you change the voltage across a membrane, proteins can change the membrane by moving.
ex. charged amino acids want to move in response to the change in voltage some open when something binds to them (which produces the conformational change) |
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Gated Ion Flow
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ions present at different concentrations across the membrane want to flow from one side of the membrane to another by diffusion
difference also produces a force for the ion flow. -if inside of cell is (-), (+) ions tend to flow inward and (-) outward. when channels open in the membrane, they provide a pathway for ion flow from one side to the other driving force then moves ions through the channels according to the sign of the diffusive electrical gradients flow of ions across the membrane produces a current, flow of current produce a change in membrane potential |
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What are the two forces that combine to produce a driving force?
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diffusive and electrical
diffusion is due to random molecular motion, not direct movement through the channel. |
