Hey,
I just did the 2017 VCAA exam and I felt like did alright except for the last question. There is just so much information that I've literally never learnt, such as zeitgeibers, the suprachiesmatic nucleus (SCN), hypothamulus, pineal gland. Can anyone please explain what they are because my teacher told us to specifically not learn this stuff so I'm feeling kind of stressed.
Thanks!!
No need to stress, this stuff is quite easy to learn so i'll try break it down for you
this is from the key knowledge:
sleep as a regular and naturally occurring altered state of consciousness that follows a circadian rhythm and
involves the ultradian rhythms of REM and NREM Stages 1–4 sleep
Circadian rhythms are biological rhythms that follow a 24 hour cycle. sleep can be considered as part of a circadian rhythm, due to the sleep wake cycle, which involves the alternation between periods of sleep and periods of wakefulness over a 24 hour period.
Circadian rhythms are influenced by internal and external factors. These factors are known as endogenous factors and zeitgebers.
-endogenous factors: are factors that are intrinsic to an individual, and are associated with their physiological functioning that can influence their circadian rhythms, with regards to sleep, the primary endogenous factors include the interaction between the superchiasmic nucleus and the pineal gland in regulating the secretion of melatonin and inducing physiological changes that are associated with sleep or wakefulness.
-zeitgebers: (are German for 'time givers') and they are external/extrinsic factors that originate within the environment that can influence circadian rhythms, with regards to sleep, the zeitgeber involved is light from the external environment, which is involved in influencing the sleep wake cycle.
these two factors interact to regulate a person's sleep-wake cycle
Light from the external environment acts as a zeitgeber ---- it is detected by the eyes --- it travels to the superchiasmic nucleus through neural connections between the hypothalamus and the optic chiasma--- the superchiasmic nucleus is a cluster of neurons located in the hypothalamus that contains neural links to the pineal gland and the optic chiasma and is involved in influencing the sleep wake cycle (it is also known as the body's biological clock {u probably vaguely remember this from unit 1} ) ----- if the SCN detects an intense quantity of external light (indicative of day time) ---- it will send signals to the pineal gland in the brain to cease the release of the hormone melatonin into the bloodstream, complementary to this are secondary signals will promote an increase in the hormone cortisol in the blood stream --- this will influence one to remain awake and alert during the day. ----- if the SCN detects low quantities of external light (indicative of darkness/nigh time)---- it will signal to the pineal gland to increase the release of melatonin into the bloodstream, melatonin is responsible for introducing feelings of drowsiness and sleepiness influencing one to feel tired and fall asleep at night time.
other stuff you can know:
- endogenous factors are more influential than zeitgebers on the sleep-wake cycle (that is the SCN will function as stated above in the absence of any light) this is from a study on the influence of light on the circadian rhythms of rats, where it was found that their sleep-wake cycles functioned as normal in the absence of light
- The sleep wake cycle is actually longer than 24 hours, which is why travelling west (and hence having to delay your sleep wake cycle) is easier done than travelling east
-in the adolescent sleep wake shift the functioning of the SCN (interaction with pineal gland) is delayed by 1-2 hours
- in bright light therapy the light from the light box is a zeitgeber and it manipulates the SCN (which is why it is effective in treating circadian phase disorders)
if my attempt at making a flow chart doesn't make sense just let me know and i'll scan my notes. Don't stress though, it's good you found this gap in your knowledge now... but don't let this make you paranoid and doubt yourslef on the exam