6c Flashcards
Outline what a biological rhythm is.
Biological rhythms are repeated biological processes that that are regulated by internal mechanisms.
Outline what a circadian rhythm is, with a relevant example.
Circadian rhythms are biological and behavioural changes that occur as part of a cycle that lasts around 24 hours. An example is the sleep-wake cycle.
What is a sleep-wake cycle?
A sleep-wake cycle is a 24 hour cycle that is made up of time spent sleeping, and time spend awake and alert.
How is the sleep-wake cycle a circadian rhythm?
The sleep-wake cycle is a circadian rhythm as it involves biological changes that occur over a 24 hour period, as individuals transition from sleep to wakefulness. There are biological mechanisms that help regulate the sleep-wake cycle, including the suprachiasmatic nucleus and melatonin.
Outline what an ultradian rhythm is + example .
An ultradian rhythm are biological and behavioural changes that occur as part of a cycle that lasts less than 24 hours. Example, sleep episode.
How many sleep cycles are typically in a sleep episode?
5 or 6.
Why are sleep cycles considered to be an example of ultradian rhythm?
This is because sleep cycles involve changes in physiological activity that repeat in a cyclic manner in less than 24 hours.
What is the Suprachiasmatic nucleus (SCN)?
The SCN is an area of the hypothalamus that is responsible for regulating an individuals sleep-wake patterns.
How does the SCN regulate the sleep-wake cycle?
First of all, the SCN receives both internal and external cues that help modulate the circadian rhythm.
- External cues involves information from the environment, such as the presence or absence of light.
- Internal cues involves information that originates within the body, (such as the impression or expression of genes, known as clock genes).
How does the SCN transmit information to promote sleep and wakefulness?
The information from our internal and external cues dictate the messages that the SCN sends to the pineal gland and the adrenal cortex.
What role does the pineal gland play in promoting sleep?
The information from our internal and external cues dictate the information our SCN sends to the pineal gland, which is a gland responsible for the release of melatonin.
What is melatonin?
melatonin is a hormone released typically at night to help induce sleep, as part of the sleep wake cycle.
Describe the process of melatonin throughout the day.
At the onset of darkness in the evening, levels of melatonin start to rise.
At around 8-9pm, melatonin levels should reach a level that starts to induce a sense of calmness, and thus promote sleepiness.
This leads to an individual naturally wanting to induce sleep at around 10-11pm.
Melatonin peaks between 2-4am, when individuals are typically in the deepest sleep, before gradually declining over the night and before waking up.
True or false:
Melatonin directly induces sleep.
This is false, as melatonin does not directly induce sleep, but rather promotes a sense of calmness and relaxation, which naturally helps to induce sleep.
How does melatonin promote sleep?
Once melatonin is produced and released, it travels to all areas of the body, via the bloodstream. The levels of melatonin thus helps regulate the sleep-wake cycle.
