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B What are the major events of an action potential and what ion changes are associated with each event?
During an action potential, the major events include depolarization (sodium channels open, sodium ions enter the cell), repolarization (potassium channels open, potassium ions leave the cell), and hyperpolarization (potassium channels close slowly leading to an overshoot of the resting membrane potential). Sodium influx causes depolarization, while potassium efflux causes repolarization and hyperpolarization.
The greater influx of sodium ions results in what of the membrane?
The greater influx of sodium ions results in membrane depolarization. This is because sodium ions carry a positive charge, which leads to a decrease in the membrane potential towards zero or a positive value.
Is the sodium potassium pump a carrier protein?
Yes, the sodium-potassium pump is a type of carrier protein that helps transport sodium and potassium ions across the cell membrane.
The interior of the cell becomes less negative due to an influx of sodium ions?
The influx of sodium ions causes depolarization of the cell membrane, making the interior less negative. This depolarization can trigger the opening of voltage-gated ion channels, leading to the propagation of an action potential. Sodium-potassium pumps work to restore the original ion concentrations, repolarizing the cell.
Does a sodium-potassium pump require an integral protein?
Yes, because integral proteins extend all the way though the cellular membrane which is necessary because potassium has to be brought from the outside of the cell to the inside and the sodium has to be brought from the inside of the cell to the outside.
Does action potential involve the influx of negative ions to depolarize the membrane?
No. The negative ions stay within the cell (neuron).An action potential begins (rising phase) with an influx of sodium, a positive ion or cation. The rising phase ends (falling phase) with an efflux of positive ions (potassium). The membrane potential is stabilized again with the action of the ATP dependent sodium-potassium pump.
What is the action potential produce by?
The action potential is produced by the movement of ions across the cell membrane, specifically the influx of sodium ions followed by the efflux of potassium ions. This creates a change in voltage across the membrane, resulting in the depolarization and repolarization phases of the action potential.
What are the two processes that stop an action potential from rising above 30 mV?
The two processes that prevent an action potential from rising above 30 mV are the opening of voltage-gated potassium channels, leading to potassium efflux, and the closing of voltage-gated sodium channels, preventing further sodium influx. These processes help return the membrane potential to its resting state.
What is the sequence of events of a threshold potential?
Death.
During the action potential?
During the action potential, there is a depolarization phase where the cell membrane potential becomes less negative, followed by repolarization where it returns to its resting state. This involves the influx of sodium ions and efflux of potassium ions through voltage-gated channels. The action potential is a brief electrical signal that travels along the membrane of a neuron or muscle cell.
What membrane potential becomes more positive or less negative?
A membrane potential becomes more positive or less negative when the cell experiences depolarization. This occurs when there is an influx of positively charged ions, such as sodium (Na+), into the cell, which reduces the negativity of the resting membrane potential. This change can trigger action potentials in excitable cells, such as neurons and muscle cells, facilitating communication and contraction. Conversely, hyperpolarization makes the membrane potential more negative, typically due to the influx of chloride ions (Cl-) or efflux of potassium ions (K+).
B What are the major events of an action potential and what ion changes are associated with each event?
During an action potential, the major events include depolarization (sodium channels open, sodium ions enter the cell), repolarization (potassium channels open, potassium ions leave the cell), and hyperpolarization (potassium channels close slowly leading to an overshoot of the resting membrane potential). Sodium influx causes depolarization, while potassium efflux causes repolarization and hyperpolarization.
Can an excitatory synapse only one type of channel open allowing both sodium and potassium to diffuse stimultaneously in opposite directions and still allowing depolarization to take place?
Yes, this is possible through the activation of ionotropic receptors that are permeable to both sodium and potassium. These channels allow for the influx of sodium and efflux of potassium simultaneously, causing depolarization of the postsynaptic cell due to the net positive charge entering the cell.
Binding of the neurotransmitters with muscle membrane receptors causes the membrane to become permeable to sodium resulting in the influx of sodium ions an what of the membrane?
depolarization
When hinding of the neurotransmitters with muscle membrane receptors causes the membrane to become permeable to sodium resulting in the influx of sodium ions and what membrane?
action potential of the sarcolemma(the membrane)
The greater influx of sodium ions results in what of the membrane?
The greater influx of sodium ions results in membrane depolarization. This is because sodium ions carry a positive charge, which leads to a decrease in the membrane potential towards zero or a positive value.
Influx of Na plus till 70mV?
The electrical potential difference across a cell membrane (the resting potential) is around -65 mV, inside negative. In nerve cells (neurones) or muscle cells this potential difference is reversed during an action potential. Sodium (Na+) channels open and Na+ ions enter the cell down their concentration gradient. This entry of positive charge depolarises the membrane ie it cancels out the resting pootential and then reverses it, so the potential becomes positive inside and negative outside, giving a potential of about +50mV.
