The circadian rhythm is influenced by light-sensitive retinal proteins that trigger signals to the

Suprachiasmatic nucleus.

Explanation:

Suprachiasmatic nucleus may be defined as the small region present in the hypothalamus region of the brain. They are present or situated right above the optic chiasm.

They are also regulated by the chemical and the hormonal changes. The circadian rhythm is also influenced by the suprachiasmatic nucleus. These nucleus regulates the rhythm by the retinal proteins that are light sensitive and triggers the signal in the suprachiasmatic nucleus.

Thus, the answer is suprachiasmatic nucleus.

what effect does exercise have on the nervous system?

the answer is c.

well say a good goal is to do 150 sit ups in a week! or 90 pull ups a day. even 60 push ups in a month these are all fair goals!