Lecture 4: Circadian Clock Flashcards
What does free run mean?
A biological rhythm exists without any external input or cues
What does entrainment mean?
A biological rhythm is synchronised to an external oscillation
Describe the of the circadian clock?
Endogenous molecular pacemaker
Network of interacting proteins
The central dogma is the most conserved mechanism of the circadian clock
What are the 4 properties of the circadian clock?
Period is stable over different temps
Oscillation persists under constant conditions
Events recur over approx. 24 hours
Rhythm entrainment over sun or light or temp
What are the 3 main parts of circadian systems?
Core
Input
Output
What do Zeitgebers do?
Harmonise the clock neurons to the environment
How does light reach the clock neurons?
By photoreceptive organs containing rhodopsins
What in the clock neurone is activated by light?
Cryptochrome
Mice have PER and CRY, what do flies have?
PER and TIM
What are the roles of pigment dispering factor neurons?
Output transmitter of the clock
Internal zeitgeber
Phase oscillation of clock neurons to right time of day
Light input and arousal factor
What clock neurons promote morning activity?
s-LNvs
DN1s
What clock neurons promote evening activity?
LNds
5th PDF-negative s-LNv
DN1s (weakly)
What is sleep regulated by?
The circadian clock
When you are sleep deprived, what drive gives you aa stronger desire to sleep?
Homeostatic drive
What neuroanatomy are sleep control centres in flies?
Mushroom bodies, fan shaped bodies, ellipsoid body
