Neuron Function Worksheet

Neuron Function Worksheet what is the job of a neuron - to move an electrical signal from one place to another in order to send sensory messages throughout the body Which of the gated embedded proteins in Model 1 allow sodium ions ( O ) through the membrane? - gates A, B, D and F allow sodium ions through the membrane Which of the gated embedded proteins in Model 1 allow potassium ions ( triangles ) through the membrane? - Gates C, E, and G allow potassium ions through the membrane The neuron illustrated in Model 1 has received a signal from either a sensory cell (taste bud, skin cell, retinal cell, etc.) or from another neuron. What evidence do you find in diagram 1 of the model that indicates a signal has been received? - A signal Ligand has bound to the ligand- gated embedded protein and the gate has opened In diagram 2 of Model 1, gated embedded protein B has opened. Was this opening triggered by the arrival of a signal ligand? If no, propose an alternate stimulus that might have triggered the gate to open. - No, diagram 2 does not show a ligand bound to embedded protein B. The gate may have opened because of the change in membrane potential from the flood of ions nearby When a signal moves down the axon of the neuron, which direction do sodium ions move through the voltage-gated embedded proteins? - sodium ions move into the cell when the sodium gates are opened What does the movement of sodium ions across the membrane do to the membrane potential near the open embedded protein? - the membrane potential increases (gets more positive) as the sodium ions move into the cell When a signal moves through the axon of the neuron, which direction do potassium ions move through the voltage-gated embedded proteins? - potassium ions move out of the cell when the potassium gates are opened What does the movement of potassium ions across the membrane do to the membrane potential near the open embedded protein? - the membrane potential decreases ( gets more negative) as the potassium ions move out of the cell when a neuron is resting the cell membrane is said to be POLARIZED - how is the degree of polarization measured? - the degree of polarization is measured by the cell membrane potential the gated embedded proteins in the axon of a neuron are triggered to open by changes in electrical potential across the membrane. - the voltage at which they open is called the threshold potential Looking at model 1 What is the threshold potential that causes the sodium ion gates to open? - the sodium ion gates open at -55 mV Looking at model 1 At what potential are the potassium ion gates fully open? - the potassium ion gate open at +35 mV looking at model 1 at what potential are the sodium ion gates closed - the sodium ion gates close when the membrane potential reaches +35 mV At what potential are the potassium ion gates closed? - The potassium ion gates close when the membrane potential reaches -80 mV