In O'Brien's excerpt those sentences are: <span>In a way, it seemed, he was part of the morning fog, or my own imagination, but there was also the reality of what was happening in my stomach. This sentence evokes a bodily reaction and calls it "the reality". It is not just imagined; it really happens. </span><span>I tried to swallow whatever was rising from my stomach, which tasted like lemonade, something fruity and sour. It's as if his body has its own way of processing the distressing information. He feels a very specific kind of nausea, triggered by his mental processes.
In Steinbeck's excerpt it's these sentences: </span><span>In all kinds of combat the whole body is battered by emotion. The ductless glands pour their fluids into the system to make it able to stand up to the great demand on it. They describe a very physical reaction, which is a product of emotional distress. It's as if the body is trying to defend the whole system from detrimental factors.</span>
What would happen to writing if paragraphs didn't exist is that when the reader reads the writing, he/she might skip a sentence or even get confused. And then you might not understand it yourself. It can affect the reader by not understanding what is going on in the writing if it's a story.
Quotes, punctuation or descriptive words depending on the situation. (idk if this will help, need more context to fully understand the question)
