I found this sentence from my notes which I cannot understand

PR &lt; CO, CO $\uparrow$, PR &gt; CO $\downarrow$


where

\item CO = AP / PR, Cardiac Output = Arterial P / Peripheral Resistance


I cannot understand the first sentence.
I cannot understand how you can deduce by Ohm's law the relationship.

What is the point of the first sentence?


Question: Help me identify this spider from my garden
Answer: It looks like Neoscona Crucifera to me, but I could be wrong.

Here is a picture of her: 



Another one, only this is more of the web: