ppwt 5 Flashcards
(25 cards)
explain the core clock in animals
Bmal 1 and clock will bind to ebox (DNA)
they can form
- CRY1 and PER which will go to the nucleus and inhibit BMAL and clock -> negative feedback. Inhibit gene expression
- it will make ROR and REV. ror - stimulates the bmal 1 box and rev will inhibit
rev will
ror will
cry1+ per will
inhibit bmal 1
estimulate bmal
inhibit gene expression
explain endogenous mechanism
signal from the brain independent of external cues
circadian rhythm
24h cycle
hormone secretion, sleep-wake, body temperature
infradian rythm
longer than 24h cycle
reproductive cycle, hibernation, breeding
ultradian rhythm
shorter than 24h cycle
sleep stages, heart beat
what are some peripheral clocks and give some examples
external cues can change internal ones. For example temperature can change heart beat, pathogens - immune system etc
what are some examples of circadian rhythms
cortisol secretion, growth hormones, PRL
when is the max cortisol secretion? and GH?
cortisol is maximal between 6-8 am
and GH is maximal 1h after going to sleep
can circadian rhythms change during development? if yes give an example
yes, gonadotrophin is released mainly at nigh doing puberty but in adults it releases in pulsative fashion
why do we need to take rhytms into account when we measure hormone levels
because we need to see if the hormone in its “normal” rhytms has a hypo or hyper function
true or false
circadian thytms can be seen even if infradian rhythms
true
what is the pacemaker of the circadian rhythm
SCN - suprachiasmatic nucleus neurons
how much time is the circadian rhythms
more than 24h
what is the main stimulus that enters the SCN
Light
explain how light is connected to the SCN
scn receives light by the retinohypothalamic tract - which has a neural connection form retina to the SCN
Where does SCN regulate melatonin
pineal gland
when do melatonin levels peak
in the middle of the night
how is pineal gland involved in the control of circadian rhythm
because it secretes melatonin
explain the correlation between melatonin and other hormones
if someone is sleep less, the growth hormone will decrease because it is related to melatin at night
what are other functions of melatonin
- adjust jet lag
- aid elderly sleep
- antioxidant, anti agent ( but in a high concentration)
- enhance immunity, tumor therapy - not clear evidence
side effects of melatonin
- day time sleepiness
- desensitization of melatonin if doses too high
- adverse events with those that has seizures
explain - and + control
-: endocrine tissue produce hormone impact target cell which produce metabolite or hormone to inhibit endocrine tissue production of hormone
+: endocrine tissue produce hormone, acts on target tissue, which produces hormone that will reinforce hormone production by endocrine
explain the central control and what does it impact
hypothalamus -> pituaitary -> target gland