7C- internal body mechanisms that regulate sleep wake patterns Flashcards
circadian rhythm
biological processes that coordinate the timing of body activities over a 24hr period
ultradian rhythm
biological processes that coordinate the timing of body activities over a period of less than 24hrs
suprachiasmatic nucleus
a master body clock in the hypothalamus that regulates body activities to a daily schedule of sleep and wakefulness
zeitgeber
an environmental cue such as light, temperature and eating patterns that can synchronise and regulate the body’s circadian rhythm
melatonin
a hormone that induces drowsiness and decreases cell activity
contrast the circadian and ultradian rhythm
A circadian rhythm is a biological process that follows a 24-hour cycle. An ultradian rhythm is a biological process that follows a cycle that is less than 24 hours. there can be ultradian rhythms in the circadian rhythm
what occurs in a circadian rhythm
controls the sleep wake cycle, release of hormones and regulation of body temperature.
what are some ultradian rhythms
may last for a few minute to a few hours
heart rate, digestion, blood pressure, hormone secretions and apetite
give an example of an ultradian rhythm
the sleep portion consists of several sleep cycles occuring as ultradian rhythms.
sleep cycles tend to increase in length over the course of a sleep episode, with a general pattern of increased sleep and degreased N3 sleep as we progress through each ultradian rhythm
what does the SCN do
functions as teh mast body clock and sends signals to regulate various activities in the body, keeping it functioning to a daily schedule of sleep and wakefulness
it can function independently to maintain an approximately 24 hour cycle because of a precise feedback loop of gene expression and inhibition.
can be influenced by zeitegebers and is particularly sensitive to light
What is the role of the suprachiasmatic nucleus in the sleep-wake cycle?
The suprachiasmatic nucleus acts as a master clock that synchronises the sleep-wake cycle through a feedback system involving the detection of light.
What is the name of the hormone that induces sleepiness and decreases cell activity in the body?
melatonin
Identify an example of a sleep-related biological process that follows a circadian rhythm and a process that follows an ultradian rhythm.
Circadian rhythm: The sleep-wake cycle
Ultradian rhythm: One 90-minute sleep cycle
Explain why dark lighting conditions are ideal for sleep.
Melatonin is secreted when a person is exposed to low levels of light or darkness. Melatonin induces sleepiness and decreases cellular activity.
Explain the interaction between the role of the suprachiasmatic nucleus and melatonin in the regulation of a person’s sleep–wake patterns.
The suprachiasmatic nucleus detects the amount of light received by the retinas of the eyes and signals to the pineal gland whether to secrete melatonin to induce sleepiness, or to suppress melatonin secretion.
