In health you have white blood cells (green cars) circulating round the blood (road), looking for an infection to kill. These are normally kept out of brain (carpark) by the blood brain barrier (ticket barrier).In multiple sclerosis, the disease triggers the barrier to open allowing white blood cells to enter the brain.
As you suggest, once inside the brain, it’s demolition/destruction derby. In MS the white blood cells attack your nerve cells (the myelin-forming cells to be precise) as if they were an infection, and cause damage. This is the start of MS being noticed.
You’re half way there. More Next Time, When we look at how we respond to the attack
To be continued TTFN
Cut to the chase, with a more complex description