A&P 1

2401-20F EXAM 4

Name_____________________________

Microelectrodes are inserted into a neuronal cell, and the potential was recorded at points A and B. The potential is shown in Table 1. The electrodes at A and B are 30 mm apart. Based on the data presented here, answer the questions (1)~(4). 10 points total

Table 1. Membrane potential at points A and B.

Time (ms)	Vm (mV) at A	Vm (mV) at B
0	-70	-70
0.4	-52	-70
0.8	37	-70
1.2	-15	-70
1.6	-75	-55
2	-80	38
2.4	-75	-18
2.8	-70	-70
3.2	-70	-82
3.6	-70	-75
4	-70	-70

(1) In the graph below, plot the data. Use two different colors or styles of lines for the data at points A and B. (4 points)

(2) Do the graphs resemble action potential? Why or why not? (1 point)

(3) Given that the distance between point A and point B is 30 mm, calculate conductance velocity (speed) of the neuron in m/s (4 points). Assume the same depolarization event was passing points A and B. Show the steps to get full marks.

(4) Based on your answer in (3) and Table 2, what kind of neuron is shown above? (1 point)

Table 2. Velocity of nerve conduction.

Neve fiber type	Conduction velocity
Myelinated alpha	70-120 m/s
Myelinated delta	12-30 m/s
Unmyelinated	0.2-2 m/s

0 0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4 -70 -52 37 -15 -75 -80 -75 -70 -70 -70 -70