Biological Rhythms (1)
Rhythms with two defining characteristics: 1) they recur at regular intervals and 2) they are generated by a biological organism. They are grouped according to their period and named after their frequency. (1)
Ultradian
A rhythm with a period less than 24 hours
Circadian
A rhythm with a period approximately 24 hours
Infradian
A rhythm with a period greater than 24 hours
Mimosa
In the 1729, a French geophysicist/
astronomer named Jean-Jacques d'Ortous
de Mairan became interested in the leaf
movements of the ________ plant - leaves
open during the day and close at night (first evidence that biological rhythms are endogenous)
Rhythm
a reccurent event. can be characterized by its period, frequency, amplitude, and phase
Period
the length of time required to complete one cycle of the rhythm (the amount of time from peak to peak or trough to trough)
Frequency
the number of completed cycles per unit of time
Amplitude
the amount of change above and below the average value
phase
represents a point on the rhythm relative to some reference time point during the cycle
phase relation
where you are in relation to another rhythm, which can be a biological or environmental rhythm
Homeostasis
claims resistance to change, maintenance of "set points", bounce back after unpredictable events
Biological Rhythms (2)
claims programmed changes, ensures variability, and allows preparation for predictable events (2)
Eskinogram
Input from environment --> Clock (internal time keeping machine) --> Output to rest of body
free-running
a rhythm in an animal when exogenous cues have been removed
general
if a rhythm is not generated by an endogenous clock or it has not been tested, we use a more ______ term like daily rhythm, seasonal rhythm, etc.
entrainment
the environment matches the endogenous rhythm to the external environment in a process called __________
zeitgebers
stimuli that entrain biological rhythms (time-givers)
generate, entrain, communicate time information
endogenous clocks ________ the rhythm, environmental cues ______ the rhythm of the clock to the environmental cycle, and the output systems ___________ ______ _________ from the clock to the body.
light-light, dark-dark, light-dark
LL, DD, LD (three terms separated by commas)
Period (tau)
the length of time required to complete one cycle of the rhythm
Alpha
Greek letter meaning active phase
Rho
Greek letter meaning inactive phase
subjective day
the daytime portion of the organism's endogenous rhythm
subjective night
the nighttime portion of the organism's endogenous rhythm
double plotted actogram
a graphical representation of an animal's sleep-wake cycle in which the data has been plotted side by side with every other day repeating so the graph is easier to read
transients
the time in which cycles are out of phase when an oscillator is entraining
oscillator
any endogenous system capable to generating a self-sustaining rhythm in the absence pf rhythmic input
pace-maker
an oscillator capable of setting the period and phase of an overt rhythm
Circadian Rhythm(s)
Three Properties of ______________ ___________
1) self sustaining oscillators persist in constant conditions
2) oscillators take several cycles to entrain
3) oscillators can only entrain to cycle lengths close to their endogenous period.
True
(True/False) You can decide whether a certain rhythm is the result of an endogenous circadian oscillator by making sure it aligns with the Three Properties of Circadian Rhythms.
positive masking
induction of overt behavior without influencing the underlying clock is called _______ _________
ex. sounding a buzzer at the same time everyday
negative masking
suppression of overt behavior without influencing the underlying clock is called ________ _________
ex. placing an animal under anesthesia
false
(true/false) oscillators can manage rhythm of pacemakers, but pacemakers can only influence rhythm-less tissue
true
(true/false) entrainment adjusts period and phase
parametric entrainment
light acts through continuous modulation to entrain the circadian clock
non-parametric entrainment
light acts at discrete phases (dawn/dusk) to entrain the circadian clock through instantaneous phase shifts each day
Phase Response Curve (PRC)
a graph created by using the mean adjustment in period by giving a burst of light during different parts of a cycle depicting an animals limits of entrainment. it allows you to predict the behavior of an animal in response to light, whether it is a single
dead zone
Light pulses during the animal's subjective day fall in the ____ ____
phase delay
light pulses during an animal's early subjective night results in a ______ _______
phase advance
light pulses during an animal's late subjective night results in a ______ _________
period, phase
Light entrainment determines ______ and _______ (alphabetical, separated by commas)
true
(true/false) Entrainment on the positive slope of a PRC is not used because it would function as a positive feedback loop. if light hits the PRC shallower on positive slope, cycle would continue to delay
Aschoff's Rule (The Circadian Rule)
The rule that states that, in nocturnal animals, increases in light intensity increase tau (period) and decrease alpha (active phase). In diurnal animals, increases in light intensity decrease tau and increase alpha.
Activity, Arousal, Novelty
Three characteristics of novel wheel that might be critical for its zeitgeber effects: (alphabetical, separated by commas)
False
(true/false) exogenous melatonin can entrain animals if given in the early subjective day
food entrained
Evidence for an endogenous ________ ____________ oscillator:
1) pattern persists after removal of periodic feeding in constant conditions (food deprivation)
2) has limits of entrainment - feeding schedules between 22-31 hour cycles
3) exhibits transients
Partitioning, Synchronization
Two main categories of social influence on daily rhythms are temporal _________ and temporal __________ (alphabetical, separated by commas)
Circadian Pacemaker(s)
an endogenous self-sustained oscillator that imposes its period on, and dictates the phase of, other (subordinate) oscillators and/or non-oscillatory structures. The ____________ ___________ must also be connected to the external environment such that zei
b-mal, clock
The positive core clock genes are _________, __________, and rev-erb(alpha) (alphabetical, separated by commas)
cryptochrome, period
the negative core clock genes are ___________ and ____________. (alphabetical, separated by commas)