* not completed

. The action potential of a nerve cell

results from a large increase in the membrane permeability to sodium ions correct incorrect

can summate one with another correct incorrect

may vary considerably in amplitude correct incorrect

becomes larger as stimulus strength increases correct incorrect

* not completed

. Which of the following statements about the speed of action potential propagation is correct?

It depends on the diameter of an axon correct incorrect

It depends on the thickness of the myelin around the axon correct incorrect

It is severely reduced if an axon becomes demyelinated correct incorrect

It is fastest in unmyelinated axons correct incorrect

* not completed

. If a motor nerve has a conduction velocity of 50 m s-1 how long will it take an action potential to reach a muscle 0.5 m from the spinal cord?

10 ms correct incorrect

15 ms correct incorrect

2 ms correct incorrect

20 ms correct incorrect

* not completed

. The amplitude of an action potential recorded from a nerve trunk is graded according to the stimulus strength.

True correct incorrect

False correct incorrect

* not completed

. The speed of action potential conduction is increased in demyelinating diseases such as Guillain�Barr� syndrome and multiple sclerosis.

True correct incorrect

False correct incorrect

* not completed

. Which of the following statements about synaptic excitation are correct?

The membrane potential of the post-synaptic cell hyperpolarizes correct incorrect

The epsps are all or none in nature correct incorrect

The epsps can summate correct incorrect

After an epsp the postsynaptic cell passes through a refractory period correct incorrect

* not completed

. At the neuromuscular junction:

the muscle membrane possesses nicotinic receptors correct incorrect

the motor nerve endings secrete norepinephrine correct incorrect

neuromuscular transmission is enhanced by curare correct incorrect

the motor nerve endings secrete acetylcholine correct incorrect

* not completed

. The axons of peripheral nerves:

are always covered by a layer of myelin correct incorrect

are always associated with Schwann cells correct incorrect

only conduct action potentials from the CNS to a target organ correct incorrect

are protected by three layers of connective tissue correct incorrect

* not completed

. Nerve terminals may contain more than one kind of neurotransmitter

True correct incorrect

False correct incorrect