What feeling does Welty evoke in the reader with the use of short sentences and a quickened pace at the end?

Eudora Welty was a master of the short story, in part because she knew how to make every word, every sentence, every image count. At the end of her story, “A Visit of Charity,” she uses short sentences and sharp words to help us feel Marion’s adrenaline rushing as she manages to escape the Old Ladies’ Home and get back to the real world.
Marion, the main character of the story, is a young girl, and she doesn’t understand old people. As a result, what might be a normal rest home is described more like a witch’s dungeon, because in Marion’s eyes, that’s what it feels like. She enters through a “heavy door”; there’s a nurse who confuses her. She’s led to a “tiny room” that is “dark” and “enclosed.” The two women she’s been taken to see seem to have “claws” rather than hands. The women argue with one another irritably, and at one point the one in bed shrieks out. The entire scene is like a bad dream.
By this point in the story, Marion is absolutely terrified. She feels trapped, and she struggles to escape, as though she believes she is being held prisoner: “The claw almost touched her hair, but it was not quick enough.” Marion, runs now, down the hallway and out the door. Her pulse is racing, her heart beating out of her chest. The short sentences here – “Marion never replied,” for instance – help us to feel how scared and breathless she is. She doesn’t even have time to say goodbye to the nurse. Outside, she’s still so frightened she forces a bus to stop. Only once she is safely on the bus and away from the scary Home can she breathe a sigh of relief, taking a bite of her apple. In her mind, she has escaped, but just barely.

The story concludes with five brief paragraphs, three of them consisting of just one sentence. Some of the sentences are also short, simple sentences, such as the very last line: "She jumped on (the bus) and took a big bite out of the apple." The effect of these shorter paragraphs and simple sentences is to quicken the pace and reflect Marian's eagerness to escape the residential home. At the end of the story, Marian, the story's protagonist, feels flustered and a little bit scared, and the quicker pace evokes perhaps the quicker heartbeat and the shorter, quicker breathing of someone who is scared.
The last line of the story, quoted above, is also rather mysterious and cryptic, and the fact that it is a short sentence and its own paragraph helps to signify its importance. Indeed, the apple can be read as symbolically significant if we recall the meaning of the apple from which Eve took a bite in the biblical story of the Garden of Eden. In the biblical story, the apple is taken from the forbidden tree of knowledge. Marian's "big bite out of the apple" could symbolize the knowledge that she acquired while visiting the old ladies in the residential home. This knowledge will perhaps have a big impact upon Marian's life, as Eve's bite from the apple in the Garden of Eden had a big impact on hers.