Biological Rhythms Flashcards
Circannual rhythm
- Yearly, migratory cycle
- Controlled by day length
Circadian rhythm
- Daily cycle (ex. Human sleep-wake cycle)
- Free running/entrained
Ultradian rhythm
Less than a day (ex. Meals, sleep cycles)
Infradian cycle
More than a day (ex. Menstrual cycle)
Zeitgeber
Cues that synchronize biological rhythms
Entrainment
The process of synchronizing an endogenous biological rhythm to an environmental stimulus
Free running rhythm
Spontaneous endogenous rhythm in environments without changes in lightness
* Human: More than 24 hours on average
Retinohypothalamic tract
The tract through which light signals is transmitted from a small population o retinal ganglion cells to the SCN of the hypothalamus
The ____ tract synchronize ____ ____ rhythm with the ____/____ changes in the environment
Retinohypothalamic; endogenous circadian; light/dark
Intrinsically photosensitive retinal ganglion cells (ipRGCs)
No image forming function, but detect brightness
IpRGCs express ____, a light-sensitive substance
Melanopsin
If a blind person has intact ipRGCs, they will express ____ rhythm; if their ipRGCs are lost, they will express ____ ____ rhythm.
Entrained; free running
____ pacemaker drives cells that control the ____ occurrence of different ____ events or ____
SCN; rhythmic; physiological; behaviors
SCN is more active during the…
Light period
Lesions of the ___ lead to animals with ____ activity patterns
SCN; arrhythmic
