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LEC 14 Exam notes!
‘What time is it? I’m hungry…’
We have previously indicated that there is a central clock which ‘tell time’ and then relays
that information to peripheral clocks. The central and peripheral clocks then execute
biological rhythmicity in the organism. The gastrointestinal tract is a very large organ
system with multiple overlapping functions. It has multiple ‘peripheral clocks’.
The central (brain) and peripheral clocks of the human physiome are set by zeitgebers,
cues from the environment as to how to synchronize activities of the system. Sunlight,
ie. the solar day night cycle, is the evolutionary zietgebar for our sleep-wake‐
cycle. Moonlight, ie. the lunar cycle, likely is the zeitgebar for the menstrual cycle. The
physiome detects that light through the specialized sensory organ (the eyes), sends the
information it to visual p g processing centers in the brain where it is analyzed and then
relays that information eventually to the central clock in the brain. Information from the
central clock is then sent to peripheral clocks in a variety organs and tissues.
*Very strong in a nursing baby & mom
-may be overridden in adults by social & other external influences*
The general structure of
the GI ‘tube’ – and it has
it’s own nervous system!
-full nervous circuits exist
in GI tract
*Intestinal epithelium -
this single cell layer
inside & outside of body.*