APPENDIX

APPENDIX 1

ACTION POTENTIAL MANIPULATIVE KIT (KMAP)

Follow the instruction and answer the question given.

Phase 1

·         Close both Na⁺ gated channel and K⁺ gated channel.

·         Place 11 Na⁺   and 4 K⁺ on the outside of the neuron.

·         Place 1  Na⁺  and 11 K⁺  on the inside  of the neuron

Questions

i.              What is the name of this phase? Place the label on the graph.

ii.             Which part of the axon is more positive or more negative? Give reason for your answer.

           

Phase 2

·         Open one Na⁺ gated channel. K⁺ gated channel remain close. Move 1 Na⁺  ion across the gated channel   

Phase 3

·         As the first Na⁺   move down the axon, open the second Na⁺ gated channel, move 9 more Na⁺   into the axon.

Questions

i.              What is the name of this phase? Place the label on the graph.

ii.             Which part of the axon is more positive or more negative?

Give reason for your answer.

iii.            The opening of one Na⁺ gated channel stimulates other Na⁺ gated channel to open.  More Na⁺ move into the axon.  What is the name of the process?

iv.           What will happen if depolarization does not reach threshold level?

Phase 4

·        Close both Na⁺ gated channels.

·         Open K⁺ gated channel.

·         Move 6 K⁺ out of the axon.

Questions

i.              What is the name of this phase? Place the label on the graph.

Phase 5

·        Na⁺ gated channel remain close.

·         K⁺ gated channel close slowly.

·         Move 5 K⁺ out of the axon.

Questions

i.              What is the name of this phase? Place the label on the graph.

Phase 6

·         Move 3  Na⁺   out of the axon and 2 K⁺   into the axon using sodium potassium pump until all the ions are back where they started

APPENDIX 2

Answers and Explanation

Phase 1

The phase is called resting potential. There are a lot more ions outside the neuron than there are inside.  This imbalance of positive ions is what gives the inside of the resting neuron a less positive (or more negative) charge.

During resting potential, sodium concentration is higher at outer membrane. Potassium ion concentration is higher at inner membrane. Axon membrane is impermeable to sodium ion.  Sodium ion is prevented from entering the axon.

Phase 2

When a neuron is stimulated at one end , it causes the sodium gated channel at that end to open and sodium ions diffuse from where they are high concentrated outside the neuron into the neuron where there are less Depolarisation occur.

Phase 3

When threshold potential is reaches action potential occur. More sodium diffuse into the axon. This process is called positive feedback. With the addition of a new positive ion to the inside of the neuron, this end of the neuron is now very positively charge compared to the rest of the inside of the nerve.  The outside has thus become more negative because of the loss of positive ions. Sodium ions flow to the next region of an axon causing action potential forms at the next region of axon.

Phase 4

Inner membrane is positively charges and outer membrane is negatively charged causes the potassium gated channel to open. Potassium move from inside the neuron to out of the neuron, where they are less concentrated. This phase is called repolarisation.

Phase 5

Hyperpolarisation causes the neuron to become more negative than the resting potential.

Phase 6

At this ponts the amount of charge on each side of the membrane is restored to its original condition but the sodium and potassium ions are on the wrong side of the membrane.  In an effort to restore everything to its proper order, the sodium potassium pump will take 3 sodium ions on the inside of the neuron and move them out while taking 2 potassium ions on the outside and moving them back in.  Since the pump is moving ions against their concentration gradients, energy is required.