Week 12 — Nervous Tissue, the Neuron & the Action Potential

Why this matters

A future nurse reading why losing myelin slows signals and a driver whose foot must reach the brake fast both depend on this week's spike.

In plain language

Every touch you feel and every move you make rides on a fast electrical signal carried by one kind of cell, the neuron (a nerve cell that receives, combines, and sends signals). This week you take one neuron apart, from the branches that listen to the long fiber that talks, and you meet the 6 kinds of support cells that keep it working. You learn why a resting neuron holds a small electrical charge, and how a pump that trades 3 sodium ions for 2 potassium ions keeps that charge ready. Then you follow the action potential (the brief electrical spike a neuron fires) through its fixed order of steps, and you watch it cross a tiny gap to the next cell as a chemical. You finish with a ruler you catch after it falls about 20 cm, which turns the whole chain into a number you can measure at home.

• Already covered: Week 3's sodium-potassium pump, and Week 10's acetylcholine at the junction.
• This week: the neuron, its support cells, rest, the spike in order, myelin, and the synapse.
• How they connect: the pump builds the gradients the spike spends.
• Where we're going next: Week 13, the central nervous system.

Focus

How does a cell turn a touch into an electrical signal and pass it on?

By the end of this module, you should be able to:

• [ ] label a neuron's parts and its two myelin makers
• [ ] order the spike's phases with their ions and signed values
• [ ] trace a signal across a synapse in order

To-do

Plan your week

1. Read Chapter 12 (about 50 minutes), then the lecture and slides.
2. Work the tutorial (60–90 minutes) and practice set (20 minutes).
3. Do the A&P Lab & Inquiry (two hours), the discussion, and the assignment.
4. Take the quiz.

This week's checkpoint: put the action potential's phases in order with the ion that drives each.

You've got this

Ask your instructor early if you get stuck.

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