5) an action potential a)is initiated by potassium ion flux b)involves the influ

Question

5) an action potential

a)is initiated by potassium ion flux

b)involves the influx of negative ions to depolarize the membrane

c)involves propagation dependent on chemically gated ion channels

d)involves propagation dependent on voltage gated ion channels

6)which of the following does not affect the speed of propagation of axonal action potentials?

a)whether the axon is afferent or efferent

b)presense or absence of myelin shreath

c)diameter of the axon

d)thickness of the myelin sheath

7) continuous conduction and saltatory conduction differ in the

a) mechanism of propagation

b)type of change in RMP involved

c)type of ion channels involved

d)speed of propagation

8)if the effects of EPSPs and a IPSPs reach the axon hillock at the same time and are of the same magnitude, what is most likely to occur?

a)the axon hillock membrane will become depolarized

b)an action potential is generated more quickly than usual

c)no action potential will be generated, since the effects cancel each other

d)the axon hillock membrane will become hyperpolarize

Explanation / Answer

5. d) action potential involves special types of voltage gated channels , It involves inward movement of sodium ions , which are positively charged.

6.d) The action potential simply jumps over the myelin sheath and only touches the axon on at the nodes of Ranvier.

So it doenst matter if the myelin sheeath is thin or thick , the action potential will skip the areas of the myelin sheath.

7.d) Saltatory conduction is faster than the continous conduction. This is because the action potential only touches the nerve cells at the nodes of Ranvier. It skips the area of myelin sheath , which makes it faster than the continous conduction.

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