Purpose of Pain & Pleasure?

Purpose of Pain & Pleasure?

Hello,

By pain, I mean any displeasing or sensation a dis--ease, irritation
etc.

By pleasure, I mean any pleasing sensation, a ease, scratching etc.



"Pain is defined as( IASP) as ["an unpleasant sensory and emotional
experience associated with actual or potential tissue damage, or
described in terms of such damage".
Pain is part of the body's defense system: it triggers mental problem-
solving strategies that seek to end the painful experience, and it
promotes learning, making repetition of the painful situation less
likely. The nociceptive system transmits signals that usually trigger
the sensation of pain, it is a critical component of the body's
ability to react to damaging stimuli and it is part of a rapid-warning
relay instructing the central nervous system to initiate reactions for
minimizing injury.

* en.wikipedia.org/wiki/Pain and nociception

Pleasure is commonly conceptualized as somehow opposed to pain or
suffering, though it has received much less scientific attention.
Arthur Schopenhauer, 19th Century German philosopher, understood
pleasure as a negative sensation, as it negates the usual existential
condition, that of suffering. Pleasure can be brought about in
different ways, depending on how every individual senses the feeling
of pleasure. Some feel this phenomenon through music, sexuality,
drugs, writing, accomplishment, recognition, service, and any other
imaginable activity; even pain.
* en.wikipedia.org/wiki/Pleasure "

Pain is related to attention, withdrawls and repetitions, pleasure
should be opposite. But above or other links do not tell about
physical/physiological purpose of pain and pleasure.

Can we also think about following:-

1. These can be relating to Autonomus nervous system, pain with fight
or flight and pleasure with "rest and digest"..SNS and PNS.

2. Pain invites attention and concentration of defence/inflammatory
responses at paining site Whereas pleasure opposite...narrow-
mindedness and broad-mindedness.

3. Can variation in feeling pain, pleasure and other senstaions be
"immune status" related?

Best wishes.