ppwt 5

Question 1

explain the core clock in animals

Answer 1

Bmal 1 and clock will bind to ebox (DNA)
they can form

1. CRY1 and PER which will go to the nucleus and inhibit BMAL and clock -> negative feedback. Inhibit gene expression
2. it will make ROR and REV. ror - stimulates the bmal 1 box and rev will inhibit

Question 2

rev will
ror will
cry1+ per will

Answer 2

inhibit bmal 1
estimulate bmal
inhibit gene expression

Question 3

explain endogenous mechanism

Answer 3

signal from the brain independent of external cues

Question 4

circadian rhythm

Answer 4

24h cycle
hormone secretion, sleep-wake, body temperature

Question 5

infradian rythm

Answer 5

longer than 24h cycle
reproductive cycle, hibernation, breeding

Question 6

ultradian rhythm

Answer 6

shorter than 24h cycle
sleep stages, heart beat

Question 7

what are some peripheral clocks and give some examples

Answer 7

external cues can change internal ones. For example temperature can change heart beat, pathogens - immune system etc

Question 8

what are some examples of circadian rhythms

Answer 8

cortisol secretion, growth hormones, PRL

Question 9

when is the max cortisol secretion? and GH?

Answer 9

cortisol is maximal between 6-8 am
and GH is maximal 1h after going to sleep

Question 10

can circadian rhythms change during development? if yes give an example

Answer 10

yes, gonadotrophin is released mainly at nigh doing puberty but in adults it releases in pulsative fashion

Question 11

why do we need to take rhytms into account when we measure hormone levels

Answer 11

because we need to see if the hormone in its “normal” rhytms has a hypo or hyper function

Question 12

true or false
circadian thytms can be seen even if infradian rhythms

Answer 12

true

Question 13

what is the pacemaker of the circadian rhythm

Answer 13

SCN - suprachiasmatic nucleus neurons

Question 14

how much time is the circadian rhythms

Answer 14

more than 24h

Question 15

what is the main stimulus that enters the SCN

Answer 15

Light

Question 16

explain how light is connected to the SCN

Answer 16

scn receives light by the retinohypothalamic tract - which has a neural connection form retina to the SCN

Question 17

Where does SCN regulate melatonin

Answer 17

pineal gland

Question 18

when do melatonin levels peak

Answer 18

in the middle of the night

Question 19

how is pineal gland involved in the control of circadian rhythm

Answer 19

because it secretes melatonin

Question 20

explain the correlation between melatonin and other hormones

Answer 20

if someone is sleep less, the growth hormone will decrease because it is related to melatin at night

Question 21

what are other functions of melatonin

Answer 21

• adjust jet lag
• aid elderly sleep
• antioxidant, anti agent ( but in a high concentration)
• enhance immunity, tumor therapy - not clear evidence

Question 22

side effects of melatonin

Answer 22

• day time sleepiness
• desensitization of melatonin if doses too high
• adverse events with those that has seizures

Question 23

explain - and + control

Answer 23

-: 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

Question 24

explain the central control and what does it impact

Answer 24

hypothalamus -> pituaitary -> target gland

Question 25

what are the causes of some endocrine disorders

Answer 25

• overproduction
  -underproduction
• altered tissue response
• tumors of endocrine organ
• excessive hormone metabolism