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30 Cards in this Set
- Front
- Back
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What is the nervous system mainly made up of? (2) |
Neurons and Glial Cells |
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What are the three subtypes of neurons? |
1. Sensory Neuron 2. Motor Neuron 3. Interneuron |
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What do neutrons do? |
Send or receive electrical impulses |
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What are the four types of transport? |
1. Simple diffusion 2. Facilitated diffusion via carrier 3. Facilitated diffusion via channel 4. Active transport |
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Do channel proteins form hydrophilic or hydrophobic channels? |
Hydrophilic channels |
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Is diffusion active or passive in hydrophilic channels? |
Passive |
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Channel proteins may display a high degree of _______________ |
Selectivity |
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What part of the neuron receives signals? |
Dendrites |
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What part of the neuron transmits signals? |
Axons |
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Where is the junction in the neuron? |
At the synapse |
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Do the cytosol and extracellular space have the same or different concentrations of ions? What does this cause? |
The cytosol and extracellular space have different concentration of ions, which leads to membrane potential. |
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In terms of Na+, Cl-, and K+, where are each of their concentrations higher? |
Cl- and Na+ have higher concentrations outside of the axon and neurons; K+ has a higher concentration inside the axon and neuron |
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In terms of K+ and the impermeable anions (M-), what causes a membrane potential? |
The plasma membrane will allow potassium ions to pass through from the cytosol into the extracellular fluid; however, it is impermeable to the anions, which are left in the cytosol. This is what causes a membrane potential, which will increase until an equilibrium is reached. |
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What type of equilibrium is reached between potassium and impermeable anions? |
An electrochemical equilibrium |
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What is the Nernst Equation and what is it used for? |
Ex =(RT/zF)ln([X]outside/[X]inside) Nernst's Equation describes the relationship between an ion gradient and the equilibrium potential when the membrane is only permeable to ONE ION |
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Which one is more positive: the equilibrium membrane potential for Na+ or K+? Why? |
Na+, as there are some Na+ ions in the cell |
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What is the difference between the Nernst and Goldman Equations? |
Where the Nernst equation only deals with one ion permeating at a time, the Goldman equation describes the combined effects of ions on membrane potential. |
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What does the Goldman equation represent? |
That even during resting state, the cell is always a little permeable to sodium, chloride, and potassium ions |
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Explain the steady-state movement of ions across the plasma membrane |
Say a membrane is only permeable to K+; its membrane potential will equal the equilibrium potential for K+. If it was also slightly permeable to Na+, then the membrane potential will depolarize slightly as Na+ leaks into the cell, decreasing the restraint on K+ leaving the cell. K+ thus diffuses outward, balancing the inward movement of Na+. |
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Who were the first researchers to show how more than one ion contributes to a membrane potential? |
Goldman, Lloyd, and Katz |
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What do Pk, PNa, and PCl represent? |
The relative permeabilities of the different ions |
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Following depolarization, do ion channels become more positively charged on the cytoplasmic or extracellular side? |
The cytoplasmic side |
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How can voltage gated ion channel be deactivated? |
At the N-terminal, 20 amino acids will form a structure that can block the channel and deactivate it. |
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What causes a voltage-gated channel to open up? What happens as a result? |
Increasing the positive charge within a cell can open up the channel, allowing potassium to leave the cell. |
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What is an action potential? What ions travel where? |
Action potentials occur when the neuronal plasma membrane undergoes a quick but big depolarization and depolarization. As a result, Na+ moves in, while K+ moves out |
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What are the 5 steps during the transmission of an action potential (AP)? |
1. Membrane is totally polarized 2. Initiation of AP causes depolarization 3. As adjacent regions become depolarized, another AP starts there 4. K+ flowing out causes repolarization, while depolarization moves forward. 5. Process is repeated as depolarization moves forward. |
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How are myelinated axons produced? (2) |
Via Schwann cells and oligodendrytes |
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What is the main function of the myelin sheath? |
To act as an electrical insulator |
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Where do Action Potentials arise at? |
At the nodes of Ranvier |
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Where are action potentials triggered in myelinated neurons? |
At the axon hillock (just before the myelin sheath |
