Pineal Gland: a peanut in the brain

The pineal gland is involved in different functions in vertebrates, but looking at the mammals' function, it is involved in ... .

There is a special hormone produced in darkness which is called ... . When light hits the photoreceptors in the retina, a signal is triggered to the ... from there to the ... and then to the pineal gland; where this hormone is inhibited in a proportional way depending on the ... .

Scheme about melatonin production

The production of melatonin is initiated by a nightlife enzyme called ... which hunts ... to produce N-acetyl serotonin, and followed by ... which produces the hormone.

Which functions are carried by our friend melatonin?

Okay, you know now all its functions but...
How are the colour changes produced?

More things about MSH:
In fish and amphibians, MSH from the pars intermedia makes ... their skin, often in response to background changes.
Its size is usually related to ... and ... , increasing with the former and decreasing with the later.

The magical cells related to colour changes are ... and ... , changing the distribution of pigments in ... and ... .

MSH has other functions in humans.
Do you remember them?