w3) intro to c.rhythms

Question 1

circadian rhythm is a what type of rhythm? how many hrs?

Answer 1

biological
24 hr roughly

Question 2

characteristic of clock

endogenous
passive or not passive?
not using what stimulus?

Answer 2

generated WITHIN individual
not passive
not using light or dark

Question 3

exogenous
examples?

Answer 3

generated OUTSIDE of indivudal
external cycles, influences- beahvior, light intensity, posture, sleep/wake rhythm

Question 4

characteristic of clock

free running period is what type of rhythm?

Answer 4

close/approx to 24 hr cycle

Question 5

characteristic of clock

settable?

Answer 5

synchronize- able,
can train to cyclic env
ex: light cycle set to 24 hrs

Question 6

characteristic of clock

innate

Answer 6

genetically coded

Question 7

4 characteristics of clocks?

Answer 7

endogenous
free running period
settable
innate

Question 8

tau is the length of ? also called the p?

Answer 8

length of ENDOGENOU RHYTHM (DD/LL)
called the period of rhythm

Question 9

tau

A free running tau/period is how many hours?

Answer 9

not 24 hrs
can be 23.5 hrs - faster than 24 earlier running each day
can be 24.5 hrs - slower than 24 later running each day

Question 10

LONGER tau/period (ex: 24.5 hrs) takes faster/longer time to allign back to phase?

Answer 10

FASTER (days)

Question 11

SHORTER tau/period (ex: 23.5 hrs) takes faster/longer time to allign back to phase?

Answer 11

LONGER (months)

Question 12

how is the clock “settable”? What can be changed?
What are 2 ways to change it?

Answer 12

tau can be changed - reset clock
can make a non-24 hr clock (free running) –> match/reset back to 24 hr

1) change period - speed up 24.6 hr /slow down 23.5 hr
2) reset phase - move back the clock 1:05 to 1:00

Question 13

if a circle = a complete cycle
phase represents what in the circle?

? in time
also called o?

Answer 13

specific point in the circle
single point in time
oscillation

Question 14

phase shift moves from ? to ?
example: phase advance and delay

Answer 14

moves from 1 time point/oscillation to another time
ex: 9:00 pm melbourne –> phase shift to hk 3 hrs behind –> phase delay 6:00 pm

Question 15

phase angle is the difference between?
example?

Answer 15

reference point on oscillator/phase time #1 vs #2

melatonin onset relative to sleep onset

Question 16

DD vs LL

Answer 16

constant darkness
constant lightness

Question 17

tau is ? of the rhythm? length of endogenous DD/LL

Answer 17

period of the rhythm
length of endogenous DD or LL

Question 18

for tau

hiding in a cave, no light for a long period, clock will change tau to ? hours

Answer 18

more night/darkness DD –> tau runs MORE THAN 24 HRS
ex: 24.2 hrs

Question 19

for tau

morning person, waking up early to light exposure, clock will change tau to ? hours

Answer 19

more light LL –> tau runs LESS THAN 24 HRS
ex: 23.7 hrs

Question 20

zeitgeber
gives ?

Answer 20

time giver (usually gives light cycle)

Question 21

circadian time CT vs zeitbgeber time ZT?

both are ? points

Answer 21

both reference points
“inner day” activity onset, internal time
“outer day” light cycle on/off

Question 22

ZT lights on/day time is #
ZT lights off/night time is #

Answer 22

0-12
12-24

Question 23

phase delay (shift)

Is it for schedules more or less than 24 hrs?
add/subtract hrs?
black horizontal bars shift LEFT/RIGHT?
ex: rodent will start spinning activity later or earlier than previous time?

Answer 23

less than 24 hrs (ex: 23.5)
want to add hours
shift RIGHT
run LATER, think later mornings

Question 24

phase delay (shift)

Does the clock hand go clockwise/anticlockwise?
think CT0, CT6, CT12, CT18
ex: we want to move from CT 18 to?

is it first 1/2 or second 1/2 of night?

Answer 24

anticlockwise - delaying, slowing down
ex: CT18 to CT16 (delay 2 hrs)

first half of night

Question 25

phase delay (shift)

what type light exposure?
4 practices?

hint: think need to be awake for later hours,

Answer 25

evening light exposure (sunset walks)
strategic naps
diet, exericse, caffeine

Question 26

phase advance (shift)

Is it for schedules more or less than 24 hrs?
add/subtract hrs?
black horizontal bars shift LEFT/RIGHT?
ex: rodent will start spinning activity later or earlier than previous time?

Answer 26

more than 24 hrs (ex: 24.7 hrs)
want to subtract hours
bars shift LEFT
rodent start spinning EARLIER mornings

Question 27

phase advance (shift)

Does the clock hand go clockwise/anticlockwise?
think CT0, CT6, CT12, CT18
ex: we want to move from CT 20 to?

is it first 1/2 or second 1/2 of night?

Answer 27

clockwise- shift faster speeding up
CT20 to CT 22
second 1/2 of night

Question 28

phase advance (shift)

what type light exposure?
4 practices?

Answer 28

early light exposure (early morning surise dawn light walks)
less naps, shift to earlier bed time slowly, avoid caffeine

Question 29

phase angle

what are 2 ways to alter phase angle of entrainment?

Answer 29

change circadian period
change system sensitivity to light

Question 30

do women have advanced/delayed phase? less or more melatonin? insomnia? than men

Answer 30

ADVANCED phase
wake up earlier
LESS melatonin
MORE insomnia
trouble falling asleep, wakes earlier

Question 31

PRC phase response curve

4 main parts of PRC
1) straight line =
2) regions of stable entrainment ?
3) inc line
4) limits of entrainment is ?

Answer 31

dead zone
regions of stable entrainment
forbidden zone - shift from max delays to max advances
limits - ranges from -2 to +3 hrs show max adjustment for delays/advances to sync to

Question 32

Bees have their own language to tell other bees how to find the location of food. How does the circadian clock play a role?

Answer 32

Bees do a different intensity of “waggle dance” at different times of day, indicating where food will be available by the intensity

Question 33

You have a hamster running on a wheel in constant darkness. You wish for

You have a hamster running on a wheel in constant darkness. You wish for the animal to run earlier the next day. What could you do to make the hamster run earlier tomorrow?

A) Give a melatonin injection in the middle of the night
B) Give a light pulse around nocturnal activity onset
C) Give access to a novel running wheel in the night
D) Give a light pulse close to the end of nocturnal activity

Answer 33

D) Give a light pulse close to the end of nocturnal activity

Question 34

Which of the following schedules of light (L) and dark (D) in a 24 hour period would cause a long day plant to flower?

A) 5L:5D:1L:13D
B) 10L:14D
C) 6L:8D:1L:9D
D) Two of the above

Answer 34

C) 6L:8D:1L:9D

Question 35

What key feature of a circadian clock was demonstrated by the opening and closing of plant leaves in constant light conditions?

a.
It is innate
b.
It is endogenous
c.
It is temperature compensated
d.
It is settable

Answer 35

b.
It is endogenous

Question 36

You have a hamster running on a wheel in constant darkness. You wish for the animal to run earlier the next day. What could you do to make the hamster run earlier tomorrow?
a.
Give a light pulse close to the end of nocturnal activity
b.
Give access to a novel running wheel in the night
c.
Give a light pulse around nocturnal activity onset
d.
Give a melatonin injection in the middle of the night

Answer 36

a.
Give a light pulse close to the end of nocturnal activity

Question 37

If you put a hamster in a running wheel in the middle of the day (the inactive time of day for a nocturnal animal), what will likely happen on the next day?
a.
It will run less later that night
b.
It will start running later (delay)
c.
It will become arrhythmic (disrupted clock)
d.
It will start running earlier (advance)

Answer 37

d.
It will start running earlier (advance)

Question 38

Which of the following is a more modern purpose (not an ancient purpose) of circadian rhythms?
a.
Organisation of physiological processes
b.
Seasonal behaviour (e.g., determining mating seasons)
c.
To maintain a constant body temperature, despite environmental changes
d.
Anticipation of environmental events

Answer 38

b.
Seasonal behaviour (e.g., determining mating seasons)