L14 - Biological rhythms Flashcards
How do organisms on earth adapt to the cyclical changes?
- Passively/retroactively e.g Homeostatic mechanisms
- Proactively e.g Biological timekeepers
What are examples of things effected by circadian rhythms?
- Body temperature
- Hormone secretion (e.g. melatonin, cortisol)
- Locomotor activity
- Sleep
- Alertness/cognitive performance
- Muscle strength
- Immune function
What provides a simple way of
studying circadian rhythms in the wild and in the lab?
Monitoring Voluntary activity
What does rodent wheel-running activity display?
A near-24h ‘free-running’ rhythm in constant conditions
What are rodent wheel-running activity rhythms are synchronised (‘entrained’) to?
24h light dark cycles
What can Rodent wheel-running activity rhythms can adapt to?
Changes in environmental conditions e.g timing of light and dark cycle
What do Physiological and behavioural rhythms anticipate?
Changes in the environment
What 3 principals are necessary for a circadian rhythm to exist?
A pacemaker
A way to synchronise to environmental cues
Effector mechanisms
What is the main circadian clock?
Suprachiasmatic Nuclei (SCN) of the Hypothalamus
What is seen in a human
with SCN damage?
Disrupted sleep rhythms
What does the SCN exhibit?
Daily Rhythms in Metabolic Activity
What is significant about the neurons in the SCN?
Each neuron is an individual clock, contain an intracellular molecular clock
How does the SCN cells intracellular molecular clock work?
A transcriptional/translational feedback loop comprising of stimulatory elements (CLOCK/BMAL1) which drive inhibitory elements (PERIOD/CRYPTOCHROME)
Where does the SCN receive light information from?
via the retinohypothalamic Tract (RHT)
What regulates the melatonin release from the Pineal Gland?
Light and circadian signals from the SCN
