Question

According to Scott Freeman. answer the following questions

1. In a single neuron, what is the typical direction of signals?

a. axon to dendrite to cell body

b. dendrite to cell body to axon

c. axon to cell body to dendrite

2. For an action potential to occur, the membrane potential of a neuron must become_________, until it reaches the________.

a1. more positive, b1. more negative

a2. repolarization phase b2. resting membrane potential

c2. threshold potential

d2. hyperpolarization phase

3. True or False: For an action potential to fire, the sum total of EPSPs must outnumber the sum total of IPSPs that occur at nearly the same time on a postsynaptic neuron.

4. In the 1920's, the scientist, Otto Loewi, used heart muscle and a vagus nerve to show that indirect electrical signals are transmitted between cells who's cytoplasm are not connected. Describe his experiment and explain his results.

Answer 1

1b. dendrite to cell body to axon

Most neurons receive signals via the dendrites and soma and send out signals down the axon through cell body.

2. For an action potential to occur, the membrane potential of a neuron must become moe positive until it reaches the threshold potential.

3. True

If the sum of all EPSPs and IPSPs results in a depolarization of sufficient amplitude to raise the membrane potential above the threshold, then the postsynaptic cell will produce an action potential. EPSP is excitatory postsynaptic potential and IPSP is inhibitory postsynaptic potential.

4. Otto Lewi took the saline solution from the frog`s heart whose vagus nerve he had stimulated and applied it to the second heart. This caused the rate of the second heart to slow down. Loewi's interpretation of these results was that there was some substance released by the vagus nerve that caused the first heart rate to slow down and that substance was neurotransmitter acetylcholine.