Your brain communicates with your body using nerve impulses,...

Your brain communicates with your body using nerve impulses, electrical signals propagated along axons. Axons come in two varieties: insulated axons with a sheath made of myelin, and uninsulated axons with no such sheath. Myelinated (sheathed) axons conduct nerve impulses much faster than unmyelinated (unsheathed) axons. The impulse speed depends on the diameter of the axons and the sheath, but a typical myelinated axon transmits nerve impulses at a speed of about $25 \mathrm{~m} / \mathrm{s},$ much faster than the typical $2.0 \mathrm{~m} / \mathrm{s}$ for an unmyelinated axon. Figure $\mathrm{P} 1.55$ shows three equal-length nerve fibers consisting of eight axons in a row. Nerve impulses enter at the left side simultaneously and travel to the right. a. Draw motion diagrams for the nerve impulses traveling along fibers $\mathrm{A}, \mathrm{B},$ and $\mathrm{C}$. b. Which nerve impulse arrives at the right side first? c. Which will be last?

Your brain communicates with your body using nerve impulses, electrical signals propagated along axons. Axons come in two varieties: insulated axons with a sheath made of myelin, and uninsulated axons with no such sheath. Myelinated (sheathed) axons conduct nerve impulses much faster than unmyelinated (unsheathed) axons. The impulse speed depends on the diameter of the axons and the sheath, but a typical myelinated axon transmits nerve impulses at a speed of about $25 \mathrm{~m} / \mathrm{s},$ much faster than the typical $2.0 \mathrm{~m} / \mathrm{s}$ for an unmyelinated axon. Figure $\mathrm{P} 1.55$ shows three equal-length nerve fibers consisting of eight axons in a row. Nerve impulses enter at the left side simultaneously and travel to the right.
a. Draw motion diagrams for the nerve impulses traveling along fibers $\mathrm{A}, \mathrm{B},$ and $\mathrm{C}$.
b. Which nerve impulse arrives at the right side first?
c. Which will be last?

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Axonal Structure and Diameter

The physical properties of axons, such as whether they are myelinated and their diameter, directly affect conduction velocity. Larger diameters and the presence of a myelin sheath both enhance the speed of nerve impulse propagation, making the comparison of impulse speeds between different axons possible.

Motion Diagrams

Motion diagrams are visual tools used in kinematics to represent the positions of objects (or in this case, nerve impulses) at successive time intervals. They help illustrate constant speed motion, making it easier to compare how fast different signals travel along identical paths.

Nerve Impulse Conduction

This concept involves the transmission of electrical signals along neurons. It is fundamental to how the nervous system communicates information throughout the body, with nerve impulses traveling along axons to coordinate activities.

Myelination

Myelination refers to the process where axons are wrapped in a fatty insulating sheath called myelin. This sheath is critical because it increases the speed at which nerve impulses are transmitted by allowing the impulse to jump between the gaps known as nodes of Ranvier.

Transcript

Please give Ace some feedback