Activity A: The Resting Neuron
Fill in the blanks below using one from the paranthesis for each statement. It might be helpful to draw a picture of the axon membrane and label the extracellular and inctracellular fluids.
At rest a neuron ________ (is /is not) generating and conducting a nerve impuse.The relative difference in charge between the outside and inside of the axom membrane at rest is called the __________________ potential. At rest the membrane potential results from __________________ (equal/unequal) distribution of charges. The resting membrane potential is __________ (-55/-70) mV, with the inside being relatively more ______________ (positive/negative) to the outside.
At resting there are more __________ (K+/Na+) ions outside and more ________ (Na+/K+) ions on the inside. Na+ ions will move along their concentration or chemical gradient by _______________ (simple/facilitated) diffusion through _____________ (leak/liagnd gated) channels to the ______________ (outide /inside) of the axon. This will make the inside of the axon more _____________ (positive/negative). K+ ions will also move along their concentration or chemical gradient to the ___________ (inside/outside) of the axon making the inside more ____________ (positive/negative). The axon membrane is 75X more permeable to ______ (Na+/K+) because there are more __________ (leak/ligand gated) channels for _____ (Na+/K+).
At rest, __________ (negatively /positvely) charged proteins are found (inside/outside) the axon, because they are too large to move through the membrane. Na+ ions are _____________ (attracted/repelled) by these proteins. This movmement of Na+ is due to its_______________ (chemcial/electrical) gradient. Na+ moves to the ___________ (inside/outside) of the axon. K+ ions are also _____________ (attracted/repelled) by the proteins and remain inside the axon.
. The combination of the chemical and electrical gradient is called the ____________________ gradient. According to its electrochemical gradient Na+ always moves to the ______________ (inside/outside) of the axon and K+ always moves to ______________ (inside/outside) of the axon.
The resting membrane potential is also maintained by the action of the ________ (Na+-K+/H+-Na+ pump). This is a form of ___________ (passive/active) transport. The pump moves _____ (3/2) Na+ ions to the __________ (outside/inside) for every _____ (2/3) K+ ions moved to the _______________ (outside/inside).