People with multiple sclerosis ms experience many...

People with multiple sclerosis (MS) experience many challenging symptoms. Which statement best explains one cause of these difficulties? Loss of oligodendrocytes in the central nervous system results in absence of the myelin sheath of neuronal axons, impairing rapid saltatory conduction. An increase in the number of oligodendrocytes in the central nervous system results in an overgrowth of the myelin sheath of neuronal axons, resulting in abnormally large action potentials. Damage to ependymal cells results in stagnation of cerebrospinal fluid, damaging neurons. A loss of astrocytes causes leaked neurotransmitters and K+ to accumulate, impairing generation of action potentials.

Transcript

00:01 In this question, we want to figure out which of the following four statements they provide us best match one of the difficulties of people who have ms or multiple sclerosis.

00:10 So first, what is ms, which we need to know this to answer this problem? well, one thing we know about it is that people who have this, their immune system, essentially attacks healthy cells.

00:25 The body thinks that they are infections or bad and it basically attacks them.

00:32 Specifically, one type of cell that it attacks is a cell that is responsible for making myelin.

00:39 Well, what is myelin? this is on a nerve cell.

00:43 So let's draw a simple drawing of a nerve cell.

00:50 Okay, so in a nerve cell, myelin is essentially this part right here.

00:55 It goes along the axon, the middle portion.

00:58 And this is what helps nerve impulses or action potentials to travel through.

01:03 So with myelin, this is what we want.

01:08 Without myelin, which is sometimes called demyelinated, that is when this is not present, and it makes it a lot more difficult for this process to occur.

01:17 So with that in mind, we have four different statements, and we're going to start with the bottom and work our way up.

01:25 We want to figure out which one most closely matches this definition.

01:28 So answer choice number four talks about a loss of something called astrocytes.

01:36 So these are a type of cell.

01:43 And these cells are actually very active in people with ms because they are responsible for demilinating or getting rid of that myelin sheath.

01:54 And so you might think, well, that's exactly what ms is.

01:58 It's attacking myelin.

01:59 However, this answer choice is saying that we have a loss of those types of...

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