Basic Principles of Chronobiology

Question 1

What are the characteristics and classifications of rhythms?

Answer 1

Phase (phi)

Period

Amplitude

Rhythms can be ultradian, circadian, or infradian

Question 2

What can be inferred by an observed rhythm is not exactly 24 hours long?

Answer 2

It is endogenous (not environmentally determined)

Question 3

What is the difference between a clock and a rhythm?

Answer 3

A clock is the internal mechanism, the output is the rhythm

eg

clock: TTFL
rhythm: hormone levels

Question 4

How can you calculate the free running period from an actogram?

What happens if the free running peiod slopes left? Slopes right?

Answer 4

Calculate the time difference between two onsets of activity and divide by the number of days between the onsets

Slopes left: Ultradian FRP

Slopes right: Infradian FRP

Question 5

What are the three properties of circadian rhythms and what are examples of these?

Answer 5

ENDOGENOUS: rhythm observed in constant conditions

TEMPERATURE COMPENSATED: does not change despite changes in temperature

RESPOND TO ENV CUES: Can entrain to a Zeitgeber

Question 6

What happens when light is pulsed:

1) in early subjective night?
2) in late subjective night?

Answer 6

1) phase delay
2) phase advance