Circadian Rythem

it is determined by the brain...some parts of the medula oblingata...this is a REAL part of ur brain...it controls involintary actions such as breathing, blinking, etc... it can be changed by changing habitats or moving somewhere new with new animals/ species...kind of like evolution...
 
Enigma'07 said:
How though?
Click to expand...
It happens precisely by evolution. Animals whose circadian rhythm is significantly different from a 24 hour cycle will not have their energy peaks and their sleepy periods at the proper time of day to find food and stay safe, so they will die off.

I have heard of experiments with small, fast-reproducing animals like insects, that have been kept in artificial conditions where the light and dark periods were much longer or shorter than the earth's natural cycle. Eventually a new strain evolved that was adapted to it. I don't know too much about this. In fact for all I know it may be just a rumor. In order for the experiment to work, the environment would have to have predators and dew and all the other things that make the day-night rhythm what it is.

I do know for sure that the human circadian rhythm is not 24 hours, it's something like 26 and a half. If they lock humans in an environment where they can go to sleep and get up whenever they want and just turn their own lights on and off, they end up making the day noticeably longer than the real one. That's why if you have a life that keeps you out of natural light most of the time, you can find yourself drifting off of the 24-hour clock. Everyone needs to get at least 30 minutes of solar-spectrum light evey day to recalibrate their circadian rhythm.

I don't know what this means. Perhaps those asteroids that keep hitting our planet and creating new seas have enough force to speed up its rotation. For us to have evolved for a 26 hour day seems a little odd, there doesn't seem to be any natural advantage to it and in fact it should be a disadvantage. If hunter-gatherers don't wake up early enough, the predators who do will eat them. If they don't fall asleep early enough, they'll be stumbling around in the dark and the predators with better night vision will eat them.
 
ever since I was a kid if I have to get up at a certain time I can just concentate on a specific time before bed and I always wake within 2 minutes of the desired time (usually 2 minitues early almost never late which is interseting in itself). Am I tapping into my circadian rythm or is it something else, any guesses?
 
I'd always thought "biological clock" was essentially a layman's term for "circadian rhythm".
 
I thought of circadian rhythm as sleep/awake schelduel and biological clock as being more specific such as time of day. Once again, I'm not an expert so I could be wrong.
 
Enigma'07 said:
What deternines it? How did species develop differant ones?
Click to expand...

Virtually all plants and animals adjust their physiology and behavior to the 24-hour day-night cycle under the control “circadian clocks”. These are cycles of gene expression that wax and wane over a period of 24 hours. The protein products of these genes control the level of all sorts of hormones and endocrine functions that are appropriate for either sleep or wake. So, your cells always know what time of day it is even if you are experiencing artificial light/dark conditions. In response to changing day/night conditions (eg. traveling to another part of the world), your circadian clocks adjust the periodicity of their gene expression profiles to fit the new cycle, with a lag time of about 2 days.

Circadian clocks were first discovered in mutant strains of fruit flies whose circadian rhythms were abnormal, demonstrating that circadian clocks are an early evolutionary event. Many of the genes and proteins responsible for circadian rhythms in fruit flies have now been discovered in mammals. The initial cue that sets the period of these oscillating gene expression cycles is the detection of sunlight. Cells produce photosensitive pigments that initiate a signaling cascade to the nucleus that sets the circadian clock. Invertebrates are generally translucent, so circadian clocks are a cell-autonomous function. In other words, all cells set their own circadian clocks by detecting light themselves. In fact, if you take tissue explants of invertebrate animals, or even tissue or organs from translucent vertebrates like small fish, the tissue/organ in culture will maintain a circadian clock that responds to changes in light cycles! The cells do this independent of a brain or “eyes” to detect light. Large mammals like mice, however, are not translucent. Circadian clocks of mammals are set via light detection by the eyes. Light/dark signals from the eyes are transmitted to a part of the brain known as a suprachiasmatic nucleus (SCN). The SCN is the central controlling unit of mammalian circadian clocks by signaling to the rest of the cells in the body and dictating the periodicity of their circadian clocks.
 
Last edited:
You must log in or register to reply here.
Back
Top