The positive resting potential on the outside of nerve fibres is primarily due to the presense of ...

NEED SOME HELP PLEASE  Grin

1. The positive resting potential on the outside of nerve fibres is primarily due to the presense of ions of
a) sodium
b) potassium
c) calcium
d) chloride

2. The initial phase of the action potential (depolarization) is caused by

a) potassium ions entering the nerve fibre
b) potassium ions leaving the nerve fibre
c) sodium ions leaving the nerve fibre
d) sodium ions entering the nerve fibre

3. A nerve impulse is best described as

a) the diffusion of molecules along the neuron after the molecules have been released from the dendrites
b) a result of change in osmotic pressure between the inner and outer surfaces of the neural membrane
c) an enzymatic reaction that makes the membrane more permeable to potassium ions
d) an electrochemical process that occurs along the neural membrane.

4. The part of an action potential during which a neuron can not respond to a stimulus is called the

a) synaptic period
b) threshold phase
c) depolarization phase
d) refractory period

5. Transmission of a nerve impulse depends primarily on the stimulus

a) increasing the neuron's permeability to potassium ions and thus allowing these ions to enter the neuron
b) decreasing the potassium ions and thus allowing these ions to leave the neuron
c) increasing the neuron's permeability to sodium ions and thus allowing these ions to enter the neuron
d) decreasing the sodium ions and thus allowing these ions to leave the neuron

6. In a resting neuron, the outside of the neural membrane is

a) positive,and the sodium ion concentration is greater in the fluid outside the axon than in the neural cytoplasm
b) negative, and the sodium ion concentration is greater in the fluid outside the axon than in the neural cytoplasm
c) positive, and the sodium ion concentration is greater in the neural cytoplasm than in the fluid outside the axon
d) negative, and the sodium ion concentration is greater in the neural cytoplasm than in the fluid outside the axon.

7. Which of the following statements is true of the threshold potential?
a) it is the depolarization required to generate an action potential
b) it determines the time required for an action potential to be completed
c) it is the same electrical potential for all neurons
d)it determines the time it takes for an impulse to travel along the axon

8. The presence of cholinesterase in the human system allows
a) a recovery period by destroying acetylcholine
b) one-way impulse transmission
c) acetylcholine to continue stimulating dendrites
d) more rapid impulse conduction

9. Nerve impulse transmission across the synapse is from
a) dendrites to cell bodies
b) cell bodys to the axon terminals
c) axon terminals to the dendrites
d) dendrites to the axon terminals

10. Cholinesterase, which is released at the synapse, is inactivated by a poison. This poisoning results in
a) decreased permeability of the dendrite
b) complete inactivation of the transmitter substance
c) increased permeability of the dendrite
d) continued action of the neurotransmitter

11. An impulse moves from neuron to an adjacent neuron by
a) an axon of one neuron touching the axon terminals of the adjacent neuron
b) a chemical transmitter released by the dendrites of one neuron stimulating the axon terminals of the adjacent neuron
c) dendrites of one neuron touching the axon terminals of the adjacent neuron
d) a chemical transmitter released by the axon terminals of one neuron stimulating the dendrites of the adjacent neuron.

12. Insecticides that inhibit the action of cholinesterase kill insects by
a) causing continuous muscle contraction
b) preventing the use of ATP by the neuron
c) destroying all nerve impulses
d) preventing the transmission of impulses across the synapse