Help understanding the structure of this sentence (Typical orienting reactions include *the following the arteries* to the brain...)

Question

Typical orienting reactions include the following the arteries to the brain grow wider allowing more blood to reach it, the heart slows down and arteries to the large muscles become narrower so as to reduce blood supply to them.

It’s from an IELTS study guide.

First, I don't know why two nouns can connect without a preposition. (the following the arteries) As far as I know, The following is used to describe the list of what comes next. e.g. The following is an extract from her diary.

Another, I don't know why present participle (allowing) can come without any connector or comma. I think it might come from "which allows" and then omit "which" but in this way "which" cannot omit because "which" means "the arteries to the brain grow wider" and the sentence doesn't have a connector. In this case, there should be a comma before "allowing".

Answer 1

1. Typical orienting reactions include the following.

Can be written as a complete sentence.

2.The arteries to the brain grow wider allowing more blood to reach it, the heart slows down and arteries to the large muscles become narrower so as to reduce blood supply to them.

Can also be written as a standalone sentence. Which in this case I suggest it should be.

3 you assume "which allows" when the assumption should be to allow

the arteries to the brain grow wider, to allow more blood to reach it,

As I am suspicious that I am being used as a proofreader so I will not comment on any other mistakes I may have found. Which you have not specifically questioned.