Posted by Anonymous on Thursday, February 22, 2007 at 12:20pm.
The following statement describes, in random order, events during the transmission of a nerve impulse. Use them to answer the next \g question(s).
Event 1: Positive ions flow into the neuron.
Event 2: The resting potential of the cell membrane is restored.
Event 3: The cell membrane becomes more permeable to Na+ than to K+.
Event 4: More positive ions accumulate on the outside than on the inside of the neuron.
Event 5: The ion pumps transport Na+ out of the neuron and K+ into the neuron.
1. Which order of events first describes the resting membrane and then the sequence of events as a nerve impulse occurs?
a) 1,3,4,5,2
b) 1,5,3,4,2
c) 4,3,1,5,2
d) 4,5,3,4,2
My answer is A
2. The events from the statement that describe polarization, depolarization, and repolarization respectively are
a) 1,4,2
b) 1,5,2
C) 4,1,2
d) 4,5,1
my asnwer is D
are these correct??
For Further Reading
To determine the correct answers, let's break down the events and understand their significance in the transmission of a nerve impulse.
Event 1: Positive ions flow into the neuron.
This event is associated with the depolarization phase of the nerve impulse. When the neuron receives a stimulus, the cell membrane becomes more permeable to sodium ions (Na+), allowing them to flow into the neuron. This depolarizes the membrane, making it less negative.
Event 2: The resting potential of the cell membrane is restored.
After depolarization, the cell membrane needs to be restored to its resting potential. This is achieved by the ion pumps present in the membrane. These pumps transport sodium ions out of the neuron and potassium ions (K+) into the neuron, returning the membrane to its original state.
Event 3: The cell membrane becomes more permeable to Na+ than to K+.
This event happens during the depolarization phase and allows the influx of sodium ions into the neuron. It is crucial for the nerve impulse transmission.
Event 4: More positive ions accumulate on the outside than on the inside of the neuron.
This event is a result of the depolarization phase, where more positive ions (sodium ions in particular) accumulate outside the neuron than inside it. This build-up of positive charge outside the neuron's membrane creates an electrical potential difference across the membrane.
Event 5: The ion pumps transport Na+ out of the neuron and K+ into the neuron.
This event occurs during the restoration phase of the nerve impulse. The ion pumps actively transport sodium ions out of the neuron and potassium ions into the neuron, restoring the resting potential of the membrane and preparing it for the next impulse.
Now let's answer the given questions based on this understanding:
1. Which order of events first describes the resting membrane and then the sequence of events as a nerve impulse occurs?
Looking at the events, we can see that the resting membrane is described by Event 2 (restoration of the resting potential). Then, the sequence of events for a nerve impulse occurs with the depolarization (Events 1, 3, and 4) and the subsequent restoration phase (Event 5). Therefore, the correct answer is b) 1,5,3,4,2.
2. The events from the statement that describe polarization, depolarization, and repolarization, respectively, are:
Polarization refers to the resting state of the membrane where the inside is more negative than the outside. None of the events specifically describe polarization.
Depolarization is the phase where the membrane becomes less negative. This is described by Event 1, where positive ions flow into the neuron.
Repolarization is the process of restoring the resting potential, and this is described by Event 5, where the ion pumps transport Na+ out and K+ into the neuron.
Therefore, the correct answer is d) 4,5,1.
So, your answers are correct! If you have any more questions, feel free to ask.