The following are the main steps in the generation of an action potential?
817241
The correct sequence is (B).  Here's a numbered explanation:\n\nUnder normal conditions, potassium ions leak out of a cell faster than sodium ions leak in; as a result, a 'resting' cell membrane will have a negative potential.  Some stimulus may then cause a depolarization (movement toward neutral potential) in some small part of the membrane [4] -- this is the beginning of the action potential process.  Depolarization allows sodium ions to flood through the cell membrane [6], driving the membrane into positive potential [7].  At a certain point, the sodium channels shut down in response to the change in potential [1], and the flood reverses -- now potassium ions diffuse out of the cell in larger numbers [2].  Eventually, the sodium channels reach their normal state again [3].  The potassium channels also calm down, but just like the sodium ions before, they've gone too far, resulting in hyperpolarization of the membrane (or what is also called the 'undershoot,' because the potential goes more negative than its resting value) [5].
113785
1. At the neuromuscular juncture, ACh released by the synaptic terminal binds to receptors on the sarcolemma.\n\n2. The resulting change in the transmembrane potential of the muscle fiber leads to the production of action petential that spreads across the entire surface of the muscle fiber and along the T tubules.\n\n3.The sarcoplasmic reticulum releases stored calcium ions, increasing the calcium concentration of the sarcoplasm in and around the sarcomeres.\n\n4. Calcium ions bind to triponin, producing a change in the orientation of the troponin-tropomyosin complex that exposes active sites on the thin filaments (actin). Cross-bridges form when myosin heads bind to the active sites on F actin.\n\n5. The contraction begins as repeated cycles of cross-bridge binding, pivoting, and detatchment occur, powered by the hydrolysis of ATP. These events produce filament sliding, and the muscle fiber shortens.
62664
Kinetic, potential, nuclear, chemical and electrical.
894377
When muscles contract they use energy that is derived from food. It is a two-step process. The first step occurs in mitochondria, where the energy from molecules like glucose or fats is locked away in ATP (adenosine triphosphate). This ATP travels from the mitochondria to sites in the muscle where energy is needed, and the energy is released and used. At both of these stages there is the possibility for energy to be lost mainly as heat, causing a big reduction in efficiency. The proportion of food energy that ends up making the muscles move varies considerably between people from 15 to 30%.
324187
The cell membrane in the axon and soma contain voltage-gated ion channels which allow the neuron to generate and propagate an electrical impulse known as an action potential.\n\nSubstantial early knowledge of neuron electrical activity came from experiments with squid giant axons. In 1937, John Zachary Young suggested that the giant squid axon might be used to better understand nerve cells [2]. Since they are much larger than human neurons, but similar in nature, it was easier to study them with less advanced technology at that time. By inserting electrodes into the giant squid axons, accurate measurements could be made of the membrane potential.\n\nElectrical activity can be produced in neurons by a number of stimuli. Pressure, stretch, chemical transmitters, and electrical current passing across the nerve membrane as a result of a potential difference in voltage all can initiate nerve activity [3].\n\nThe narrow cross-section of axons lessens the metabolic expense of carrying action potentials, however thicker axons convey the impulses more rapidly. In order to minimize metabolic expense yet maintain a rapid conduction velocity, many neurons have insulating sheaths of myelin around their axons. The sheaths are formed by glial cells: oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. The sheath enables the action potentials to travel faster than in unmyelinated axons of the same diameter whilst simultaneously spending less energy to "recharge" the action potential after. The myelin sheath in peripheral nerves normally runs along the axon in sections about 1 mm long, punctuated by unsheathed nodes of Ranvier which contain a high density of voltage-gated ion channels. Multiple sclerosis is a neurological disorder which results from abnormal demyelination of peripheral nerves. Neurons with demyelinated axons do not conduct electrical signals properly.\n\nps. I think I deserve some points
161429
1) a physical stimulus, e.g. pressure\n2) a chemical stimulus, e.g. an acid\n3) an electrical stimulus, e.g. direct current
534511
spatial summation is when all the different EPSPs and IPSPs add up to generate an action potential in the axon hillock. Temporal summation has to do with time. If the signals come very close to each other, they can add up to go to threshold and produce one big action potential. Hope that helps.
780679
1 ribosomes\n2 stimuli\n3 enzyme\n4 cytoplasm
137626
"The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to (and stimulate) the myocardium (muscle of the heart). When the myocardium is stimulated, it contracts. It is the ordered stimulation of the myocardium that allows efficient contraction of the heart, thereby allowing blood to be pumped to the body.\n\nUnder normal conditions, electrical activity is spontaneously generated by the SA node. This electrical impulse is propagated throughout the right and left atria, stimulating the myocardium of the atria to contract. The conduction of the electrical impulse throughout the atria is seen on the ECG as the P wave."\n\n"An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart in the form of a continuous strip graph."\n\n"An ECG measures the electrical potential between leads placed on various points of the body."\n\n"The leads measure the average electrical activity generated by the summation of the action potentials of the heart at a particular moment in time."
874607
according to le chatelier's principle, to favour a forward reaction requires a removal of the product or increase of the reactant. and to increase the cell voltage, a forward reaction must be induced for one or both of the half cells.\n\nthere are four methods, increase H2 pressure, decrease H+ conc, increase Cu2+ conc, decrease Cu electrode mass. for the greatest cell voltage effect, are 4 methods are used simultaneously.\n\nonly option C is valid.
844758
Using the Michaelis-Menten equation.\n\nMore details on teh attached link\n\nhttp://www.le.ac.uk/by/teach/biochemweb/tutorials/michment2print.html\n\nGood luck
725588
1. concentration and pressure\n2. see sources
729864
1) for mechanical work- such as beating of cilia and flagella, contraction of muscle cell and movement of chromosomes suring cellular reproduction\n2) Transport work- moving substances across their concentration gradient (osmosis, diffusion, etc.)\n3) Chemical work- pushing of endergonic reactions to reach over the activation energy so reaction can occur.\n4) in general, what i explained above is the best way to summarize what ATP does but ATP also gives away it's Phosphate group so new protens can occur such as glutamic acid with phosphate group and ammonia forms glutamine. This is what ATP does in a cell.
282411
It's all to do with the action potential of the muscle cell. We have different sorts of them in our body...eg cardiac, smooth muscle..etc.
720665
Resting potential is determined by the weighted sum of the Nernst potential and the conductance (a measure of permeability) for each ion. Conductance plays a largest role in determining the potential. K's Nernst potential is around -90 mV while Na is around +60 mV. At rest (-70 mV), since there are more K channels allowing a slow leakage, the conductance is higher than that of Na and the potential is closer to the Nernst potential of K. During an action potential, the conductance for Na rises considerably, depolarizing the axon.
158163
Sodium and potassium ion channels open and close to mediate the signal.  There is a higher concentration of sodium outside the cell than inside and a higher concentration of potassium inside than outside.  Because of the size of the ions and the structure of their respective channels, Na+ diffuses across the membrane faster than K+.  The result is that the membrane potential starts at -70 mV, spikes at 40 mV as the Na+ ions pass the membrane, dips below -70 mV (to about -80 mV) when the Na+ channels close and the K+ channels open, and then normalizes back to -70 mV.  These ions are replenished by what you eat and drink-- those Gatorade commercials are telling the truth!  When you can't move your muscles anymore, your nerves might be out of electrolytes.  The whole system is kept at the necessary potentials with ion pumps in the nerve cell.
332420
ummm, i dont understand what ur asking, but if u wanna know how its generated, it has something to do with positive ions of a molecule flowing in one direction, and negative ions flowing in either the same of opposite direction forming direct and indirect currents, or at least that's what i think it is