Week 1 (Modules 1 -2) Flashcards
“chronobiology” comes from which Greek words?
"chrono" = time "bios" = life "logos' = study
What is chronobiology?
The study of biological rhythms from the hours to years range
What type of biological rhythm has been the most extensively researched, and why?
Circadian rhythms, because they are the most relevant to humans
What is a biological rhythm?
Any biological process, including behaviour, that repeats at regular intervals
Which two domains can a rhythm be described in?
time or frequency
In the time domain, a rhythm is said to have a _____, which is ______
- period
- the time needed to complete one full cycle
The reciprocal of period is _____, which is _____
- frequency
- the number of cycles per unit of time
Biological rhythms with a period of less than 24 are called:
ultradian
Biological rhythms with a period of 24 are called:
daily rhythms
Biological rhythms with a period of more than 24 are called:
infradian
What are “circa” rhythms?
Rhythms whose periods resemble a naturally occurring cycle in the environment
Circatidal rhythms have a period of about _____ and approximate ______
- 12.5 hours
- tides
Circadian rhythms have a period of about _____ and approximate ______
- 24 hours
- the solar day
Circalunar rhythms have a period of about _____ and approximate ______
- 29.5 days
- the lunar month
Circannual rhythms have a period of about _____ and approximate ______
- 1 year
- the solar year
What 2 things are unique about the “circa” rhythms?
- they resemble some type of environmental cycle
- they can persist for some time without the presence of these cycles
What are 2 implications of the persistence of rhythms?
- the rhythms must be generated by some internal clock (biological oscillator)
- the rhythms must synchronize with the environment through entrainment
What is a time series?
A sequence of data points collected over time
What is an acrophase?
The peak of the cosine wave on a graph
What is the difference between daily rhythms and circadian rhythms?
Circadian rhythms are caused by a biological clock, while daily rhythms can be performed solely due to light and dark phases; all circadian rhythms are daily rhythms, but not vice versa
What does zeitgedachnis mean?
Time memory in German
Why would bees need an internal clock that remembers the same time every day?
Flowers open and close around the same time each day due to sunlight – and flowers attract bees
What type of organism was brought on the first space science mission?
Neurospora crassa, or bread mold
What type of animal did Simpson and Galbraith study?
Macaque monkeys
What is a kymograph and who invented it?
A device to measure human blood pressure, invented in the 1840’s by Carl Ludwig
What did Curt Richter do?
Performed the first study of daily rhythms of rats in the 1920s
What is an actogram (or raster plot)?
Placing daily charts of activity beneath each other
What revolutionized data acquisition in the 1980s?
The invention of the personal microcomputer
What is a free run?
A rhythm that persists in a time-free environment
What is a continuous waveform?
The magnitude of each data point is on the vertical axis, and the time of each data point is on the horizontal axis
What is a period (tau)?
the duration of a complete cycle
What is entrainment?
The process in which a rhythm becomes synchronized with an environmental cycle
Zeitgeber
any periodic stimulus that can entrain a circadian rhythm
What do alpha and rho represent?
The daily active and rest phases
amplitude
the difference between the peak and the trough
Zeitgeber time
external time
photoperiod
the daily light period
scotoperiod
the daily dark period
What constitutes the validity of a curve fitting?
How close the data is to the sine wave
What is an example of sleep-dependent circadian rhythms in humans?
Blood levels of grown hormones
What is an example of sleep-independent circadian rhythms in humans?
Blood levels of melatonin
What is temperature compensation
How the body maintains its circadian rhythm despite changes in body temperature, which can speed up or slow down processes
What does endogenous mean?
internal to the organism
What does innate mean?
genetically determined
Circadian rhythms are both ____ and _____
- endogenous
- innate
Circadian rhythms were largely ignored by the sciences until ____
the 1970’s
An internal homeostatic mechanism biases certain behaviours for ____ and some for _____
- night
- day
What is homeostasis?
The mechanisms which maintain internal physiological conditions within the range necessary for life
What is behavioural ecology?
The study of how animals adapt behaviorally to environmental niches
What are chronotypes?
The particular temporal niche that an animal is adapted to
What is shiftwork disorder?
The inability to sleep in the day and stay awake at night
What is chronotherapeutics?
Finding the right dose of medicine based on the time of day to maximize efficacy and minimize toxicity
What is a biological oscillator?
The internal clock that controls biological rhythms
