The speed at which neurons conduct nerve impulses depends upon the rate of diffusion of sodium and potassium ions as well as on the resistance of the nerve fibers. Why do myelinated axons of frogs, having a diameter of 3.5µm conduct impulses at speeds of 30ms-1 whereas myelinated axons of the same diameter in a cat, conduct impulses at speeds of 90ms-1?

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TestUstad · Accepted Answer

Cats are warm-blooded whereas frogs are cold-blooded. The correct answer is that cats are warm-blooded whereas frogs are cold-blooded. Warm-blooded animals maintain a constant and generally higher body temperature, which accelerates many physiological processes, including nerve impulse conduction. The speed at which nerve impulses are conducted is influenced by the temperature of the organism, with higher temperatures typically enhancing conduction velocity.Option B is incorrect because although ion concentration gradients play a role in nerve impulse conduction, they are not the primary reason for the speed difference between cats and frogs. Option C is incorrect because the number of neurons does not affect the conduction speed of individual neurons. Option D is incorrect because the refractory period affects how quickly a neuron can fire again after an impulse, not the speed of conduction of a single impulse.

TestUstad · Answer

Concentration gradients of potassium and sodium are steeper in cats

TestUstad · Answer

The cats have more neurons transmitting the same signal

TestUstad · Answer

Neurons in cats have smaller refractory periods

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