Circadian Clocks

**Definition:** Biological mechanism that controls CIRCADIAN RHYTHM. Circadian clocks exist in the simplest form in cyanobacteria and as more complex systems in fungi, plants, and animals. In humans the system includes photoresponsive RETINAL GANGLION CELLS and the SUPRACHIASMATIC NUCLEUS that acts as the central oscillator.

**Tree numbers:** - G07.180.562.094.500

**Synonyms:** - Circadian Clock System - Circadian Timing System