Question

According to Scott Freeman,

1. Which of the 2 factors listed, best determine the membrane potential of a neuron?

a. concentration gradient across the membrane

b. charge gradient across the membrane

c. the surface area of a neuronal membrane

d. the threshold potential of the membrane

2. 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

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

a1. more positive, a2. repolarization phase   

b1. more negative b2. resting membrane potential

c2. threshold potential

d2. hyperpolarization phase

4. 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.

5. 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

Answer to first question is given here.

The membrane potential in a cell derives ultimately from two factors: electrical force and diffusion.Charge gradient across the membrane determine electrical force while concentration gradient across the membrane determines rate of diffusion.Hence the right options are a and b

.Options c is not correct because surface area does not directly influence electrical force and ion diffusion rate.It influences number of ion channels and hence permeability of ions.

Option d is not correct because threshold potential does not directly influence electrical force and ion diffusion rate.