1. What are \"ions?\" How are they involved in neural signaling? 2. (hand-out) T
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1. What are "ions?" How are they involved in neural signaling? 2. (hand-out) There are 4 mechanisms that maintain the resting potential: random motion (diffusion), electrostatic pressure, differential/selective permeability, and sodium-potassium pump Which mechanisms would result in an equal distribution of ions? Describe them 3. (hand-out)Which mechanisms would result in an unequal distribution of ions? Describe them 4. How would an equal distribution of ions inside (intracellular) and outside (extracellular) the neuron affect the membrane potential? What is the advantage of an unequal distribution? 5. Explain the role of positive and negative ions in the conduction of 6. Identify the characteristics (e.g. where, when, variation in size) of 7. Describe salutatory conduction, myelin sheath and nodes of nerve signals the a)resting potential, b)graded potential and c)action potential Ranvier 8. What is multiple sclerosis? 9. What is the "all-or-none" law? 10. What is the absolute refractory period? The relative refractory period? 11. What role does a "voltage-gated" channel play? 12. What are 2 major differences between an EPSP and an action potential? during an IPSP (hyperpolarization)? brain: EEG (electroencephalogram), ERPs (Event-related 13. What happens during an EPSP (depolarization)? What happens 14. Contrast spatial summation and temporal summation 15. Describe methods to measure the gross electrical activity of the potentials/ evoked potentials) 16. How does brain activity during epileptic seizures differ from normal brain activity? What are the symptoms of epilepsy? How is it diagnosed, and how is it treated?Explanation / Answer
1 Ans: An atom or molecule which has excess or deficiency of electrons is called as an ion. If there is excess of electrons then it is a negatively charged and is called anion. If there is deficiency of electrons then it is a positively charged and is called cation.
In neural network, neurons are transfers the information with other neurons in the form of electrical signals. These electrical impulses are also called action potentials.Action potentials are generated by special types of voltage-gated ion channels embedded in a neuron's plasma membrane. These channels works as mentioned below by using ions.
These channels are closed when the neurons is at the resting state. When these channels open, they allow an inward flow of sodium ions, which changes the electrochemical gradient, which in turn produces a further rise in the membrane potential which causes more channels to open, producing a greater electric current across the cell membrane, and so on. The process continues until all of the available ion channels are open, resulting in a large upswing in the membrane potential. The rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. As the sodium channels close, sodium ions can no longer enter the neuron, and then they are actively transported back out of the plasma membrane. Potassium channels are then activated, and there is an outward current of potassium ions, returning the electrochemical gradient to the resting state.
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