7C- internal body mechanisms that regulate sleep wake patterns

Question 1

circadian rhythm

Answer 1

biological processes that coordinate the timing of body activities over a 24hr period

Question 2

ultradian rhythm

Answer 2

biological processes that coordinate the timing of body activities over a period of less than 24hrs

Question 3

suprachiasmatic nucleus

Answer 3

a master body clock in the hypothalamus that regulates body activities to a daily schedule of sleep and wakefulness

Question 4

zeitgeber

Answer 4

an environmental cue such as light, temperature and eating patterns that can synchronise and regulate the body’s circadian rhythm

Question 5

melatonin

Answer 5

a hormone that induces drowsiness and decreases cell activity

Question 6

contrast the circadian and ultradian rhythm

Answer 6

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

Question 7

what occurs in a circadian rhythm

Answer 7

controls the sleep wake cycle, release of hormones and regulation of body temperature.

Question 8

what are some ultradian rhythms

Answer 8

may last for a few minute to a few hours
heart rate, digestion, blood pressure, hormone secretions and apetite

Question 9

give an example of an ultradian rhythm

Answer 9

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 REM sleep and decreased N3 sleep as we progress through each ultradian rhythm

Cases exist where one may wake from REM sleep, only to fall back into REM sleep.

Question 10

what does the SCN do

Answer 10

functions as the master 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

Question 11

What is the role of the suprachiasmatic nucleus in the sleep-wake cycle?

Answer 11

The suprachiasmatic nucleus acts as a master clock that synchronises the sleep-wake cycle through a feedback system involving the detection of light.

Question 12

What is the name of the hormone that induces sleepiness and decreases cell activity in the body?

Answer 12

melatonin

Question 13

Identify an example of a sleep-related biological process that follows a circadian rhythm and a process that follows an ultradian rhythm.

Answer 13

Circadian rhythm: The sleep-wake cycle

Ultradian rhythm: One 90-minute sleep cycle

Question 14

Explain why dark lighting conditions are ideal for sleep.

Answer 14

Melatonin is secreted when a person is exposed to low levels of light or darkness. Melatonin induces sleepiness and decreases cellular activity.

Question 15

Explain the interaction between the role of the suprachiasmatic nucleus and melatonin in the regulation of a person’s sleep–wake patterns.

Answer 15

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.

Question 16

melatonin release across the day

Answer 16

if more light is detected, the pineal gland’s secretion of melatonin is slowed down, promoting wakefulness.

Once synthesized, melatonin is released directly into the peripheral circulation…without being stored