안녕하세요!

답변이 너무 늦어졌네요 죄송합니다 ㅠㅠ

plasma refers to the fluid found inside of blood vessels

mostly composed of proteins and salts. (think blood without the red and white blood cells)

interstitial fluid refers to the fluid found outside of blood vessels, surrounding a cell

it's an aqueous environment in which the tissue is bathed in.

in terms of the differences in composition,

because large proteins cannot pass through the capillary walls

blood plasma often contains large amounts of proteins, compared to relatively little found in interstitial fluid.

그래서 capillaries 에서 fluid loss가 일어난다는 말은,

by definition, has to be talking about plasma

because only plasma is found within the capillaries (blood vessels).

this filtered fluid, will eventually make its way outside the blood vessels to be called the interstitial fluid.

학생이 올려주신 그림은 neuron 에 대한 설명을 할때 사용됐던 자료인데

the main thing you should be focusing on is the concentration gradient.

When we talk about propogation of neuronal signals, we talk about the influx or efflux of ions

- sodium has a higher concentration outside the cell than inside

- potassium has a higher concentration inside the cell than outside

(the reason for this is due to the constant activation of sodium/potassium pumps)

when a signal is propogated in the neuron,

it causes local (small area) changes of voltages in the neuron axon membrane

this can cause the voltage gated channels (as shown above) to change shape, allowing the "ball" to fall out of the "socket"

ultimately, opening up the passageway for sodium or potassium ions to move

The direction the ions move is only dependent on the concentration gradient.

Therefore, you can imagine the sodium ions will flood INTO the cell due to the gradient,

and potassium ions will flood OUT of the cell due to the gradient.

The diagram is simply a model to represent what the voltage gated ion channel protein looks like,

and you can imagine how this model works for both sodium and potassium ions, albeit in opposite directions.

학생의 take away 포인트는 

1. 세포 안과 밖에서 Na, K의 농도를 우선 establish 하는 것, 

2. ball and chain model of voltage gated channel proteins를 이해하는 것,

3. voltage 변화에 따라 어떠한 방향으로 Na과 K이 이동할 지 예상할 수 있는것

4. 마지막으로, 이게 왜 신경세포 action potential에 중요한지 파악하는 것이에요.

도움이 됐나요?

열공하시고 혹시 또 질문이 생기면 게시판에서 만나요! :D