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Flashcards in Circadian Rhythms Deck (81)
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1

External cue that synchronizes or helps entrain (determine or modify) an organisms internal clock

Zeitgeber (time giver)

2

What happens to melatonin levels as per and Tim drop?

Melatonin increases

3

What happens when an SCN of one animal is transplanted into another?

The pattern returns to normal in the form of the other animals rhythm

4

How does jet lag impact professional sports teams?

Teams with phase advance jet lag were more likely to lose, make mistakes, commit fouls, etc.

5

What does the suprachiasmatic nucleus (SCN) of the hypothalamus do in biological clocks?

It is the internal pacemaker that is the target of the retinohypothalamic tract

6

Examples of circadian rhythms

Body temp (lower at night), cortisol secretion (high in the morning), activity levels, and sleep/wakefulness

7

What do per and Tim inhibit?

Clock protein

8

What is always more active during light periods in nocturnal and diurnal animals?

SCN of the hypothalamus

9

What do melatonin signals do in seasonal rhythms?

Entrain circannual clock

10

When does phase delay happen?

Westward travel

11

Two types of jet lag

Phase advance and phase delay

12

What time are peak melatonin levels? What else is going on?

12-2am when per and Tim start to disintegrate

13

When is growth hormone release high and low?

High = stage 3 and 4 deep sleep
Low = waking hours

14

Control morning activity and need light for entrainment

M cells

15

What backs up the fact that the SCN is a pacemaker?

Lesion studies, selective breeding, transplants, 24 and 20 hour hamsters

16

When does phase advance happen?

Eastward travel

17

What type of phase shift is fall back?

Phase delay. Analogous to westward travel

18

Humans our relationship to seasonal (circannual) rhythms

Equatorial animals, thus circadian rhythms dominate over circannual rhythms

19

The process of resetting the biological clock

Entrainment

20

What is shift maladaptation syndrome and who is it common in?

Sleep disorder caused by disruption of circadian rhythms and melatonin signaling. Common in people who work overnight shifts

21

An endogenous circannual clock, separate from the SCN but location unknown, runs at approximately 365 days

Seasonal rhythms

22

GRAPHIC ON 8

GRAPHIC ON 8

23

When is temperature high and low?

High = waking hours
Low = sleeping

24

How do cortisol levels change throughout the day?

Highest in the morning and drop throughout the day

25

How do circadian rhythms contribute to symptoms?

Some symptoms are worse at different times of the day

26

What do the ganglion cells in the retinohypothalamic tract not rely on and what do they contain?

They don't rely on rods and cones and they contain the photopigment melanopsin (blue light)

27

Any rhythmic change that continues at close to a 24 hour cycle in the absence of 24 hour cues

Circadian rhythms

28

What releases melatonin?

Pineal gland

29

What do non-image receptor cells in the retinohypothalamic tract use?

Melanopsin

30

Larks vs owls

Larks = morning people
Owls = night people