Why does increase in extracellular potassium depolarize the neuron, whereas an outflow (intracellular decrease) hyperpolarizes it?
The potassium outflow hyperpolarizes the neuron by a normal process, in which the movement of positively charged K+ ions to the outside of the cell moves the interior-anchored voltage potential in the negative direction.The effect of increasing extracellular potassium works by a different mechanism, which is why it has a different effect. The increase of extracellular potassium has three mechanistic effects [1] that result in a sustained depolarized state:The normally present hyperpolarizing outflow of potassium (K+) is slowed down (due to a reduced potassium gradient); Less hyperpolarizing outflow is equivalent to depolarization, since there is a depolarizing inflow of sodium (Na+) that was not also slowed down by an equivalent increase in intracellular sodium. The result is a change in the equilibrium potential of the cell. [2]The increase in the membrane potential (slow depolarization) opens some of the sodium channels, which lets positive Na+ ions into the cell, further depolarizing it. [3]The slow depolarization causes partial Na+ channel inactivation to occur as well. This prevents the neuron from triggering a full action potential (extreme depolarization followed by extreme hyperpolarization). As a result, the cell remains in a slightly depolarized state but never fires. [3]------[1] Wikipedia on the mechanism of action for the toxic effect of extracellular potassium: Hyperkalemia [2] Wikipedia on "neural accommodation", the effect by which a slow depolarization puts the cell in a semi-depolarize state: Neural accommodation [3] Wikipedia on "equilibrium potential", the mechanism by which ion gradients determine the positive or negative voltage of the cell: Reversal potential
Which is more dangerous: AC or DC power?
DC can be defined as the ‘unidirectional’ flow of current. Current only flows in one direction. Voltage and current can vary over time so long as the direction of flow does not change.Lets assume that a certain battery provides 1.5 V, which can be described in graphical terms as:Electric charge in alternating current (AC), on the other hand, changes direction periodically. The voltage in AC circuits also periodically reverses because the current changes direction.*Plot of AC waveWhile considering which is more dangerous I hope you realize that 230 volts DC and 230 volts AC develop the same power in a resistor but they have different safety considerations. Its also known that 230 V AC is 325 volts peak, 650 peak to peak. So an AC supply can actually apply greater voltage than 230 volts DC.Plus the certain body facts like:-The human body works on electrical signals.-All the muscles are driven by generated signals.-When a source of sufficient voltage is applied the muscles work (contract).-Every articulation in the body is controlled by (at least) two opposing muscles. For example clenching you hands and opening them. In general one set is much stronger than the other (try it with clenching/un-clenching).-When a supply such as the mains is applied it is strong enough to drive pretty well all the body muscles.-So if you grab the mains by your hands both the clenching and un-clenching muscles will be driven and the clenching ones will win.That’s why it is said, "you cannot let go of DC, but you can (perhaps) let go of AC."This is the basis of the idea that DC is more dangerous than AC.ALSO:"Low-frequency (50–60 Hz) alternating currents can be more dangerous than similar levels of DC since the alternating fluctuations can cause the heart to lose coordination, inducing ventricular fibrillation, a deadly heart rhythm that must be corrected immediately.[14] However, any practical distribution system will use voltage levels quite sufficient for a dangerous amount of current to flow, whether it uses alternating or direct current. As precautions against electrocution are similar for both AC and DC, the technical and economic advantages of AC power transmission outweighed this theoretical risk, and it was eventually adopted as the standard worldwide."http://en.wikipedia.org/wiki/War...PS Don’t try to check this doubt by yourself.. Stay safe :P
Which is more dangerous: AC or DC power?
DC can be defined as the ‘unidirectional’ flow of current. Current only flows in one direction. Voltage and current can vary over time so long as the direction of flow does not change.Lets assume that a certain battery provides 1.5 V, which can be described in graphical terms as:Electric charge in alternating current (AC), on the other hand, changes direction periodically. The voltage in AC circuits also periodically reverses because the current changes direction.*Plot of AC waveWhile considering which is more dangerous I hope you realize that 230 volts DC and 230 volts AC develop the same power in a resistor but they have different safety considerations. Its also known that 230 V AC is 325 volts peak, 650 peak to peak. So an AC supply can actually apply greater voltage than 230 volts DC.Plus the certain body facts like:-The human body works on electrical signals.-All the muscles are driven by generated signals.-When a source of sufficient voltage is applied the muscles work (contract).-Every articulation in the body is controlled by (at least) two opposing muscles. For example clenching you hands and opening them. In general one set is much stronger than the other (try it with clenching/un-clenching).-When a supply such as the mains is applied it is strong enough to drive pretty well all the body muscles.-So if you grab the mains by your hands both the clenching and un-clenching muscles will be driven and the clenching ones will win.That’s why it is said, "you cannot let go of DC, but you can (perhaps) let go of AC."This is the basis of the idea that DC is more dangerous than AC.ALSO:"Low-frequency (50–60 Hz) alternating currents can be more dangerous than similar levels of DC since the alternating fluctuations can cause the heart to lose coordination, inducing ventricular fibrillation, a deadly heart rhythm that must be corrected immediately.[14] However, any practical distribution system will use voltage levels quite sufficient for a dangerous amount of current to flow, whether it uses alternating or direct current. As precautions against electrocution are similar for both AC and DC, the technical and economic advantages of AC power transmission outweighed this theoretical risk, and it was eventually adopted as the standard worldwide."http://en.wikipedia.org/wiki/War...PS Don’t try to check this doubt by yourself.. Stay safe :P
What are the best study tips ever?
Hey thereYou can have the burning desire on your studies by always thinking about your goal and the end result.There's a reason why we study so hard and burn the midnight oil to ace the results.That reason is our dream. We want our dreams to be true. We want our parents to be proud of us, our success and everything we do.We study to make ourselves a better person and a better human. Studies has a great impact on us. So take it seriouslyI will share with you a quick guide to increase your study hours. Mark my works and by the end of a month you will see changed in your study pattern and your concentration level will become double. Here it goesSpolier--This guide is only if you want to devote all your time towards studies and you are ready to give up your social life and focus on studies.LEAVE SOCIAL MEDIAYES. It might sound heart breaking but I have personally tried it and it worked. I just gave my 12th board exams and I used to study 12–14 hours a day.That might sound crazy but you can do too.Do not waste your time on social media. Uninstall WhatsApp Facebook Snapchat Instagram and all other apps.Wake up at 6 am everyday and study.Take a short nap for an hour and then study againHave breakfast. Take a showerStart studying againHave lunch. Take a power nap for 15minStart studying againNow in the evening sleep, go out and play or watch YouTube or talk to your family or friends or listen to music.After wards studyHave dinner take restAnd studyThat was the routine I followed and believe me even you can study for atleast 10 hours by following my routine.this is the only advice. Also you can watch motivational videos on YouTube to motivate you and study hardI hope this helped!!Upvote if you liked it!! It only motivates me to write more :)