Biopsych L10-12 Flashcards
What are biological rhythms?
Cyclical changes in physiological systems
What are the three types of biological rhythms?
Circadian
Ultradian
Infradian
How long circadian rhythms last?
24 hours
What controls circadian rhythms?
Suprachiasmatic nuclei in hypothalamus that acts as a pacemaker
What does a pacemaker do?
It constantly resets to make sure the body is in sync with the world
What sets the SCN and how?
Natural light
Via photo entrainment
What controls the sleep wake cycle?
Its under homeostatic control
And it increases gradually during the day
What is the pineal gland responsible for in circadian rhythms?
Releasing melatonin during darkness
What does melatonin do?
Induces sleep
By inhibiting neural mechanisms that promote wakefulness
Strengths or circadian rhythms
+ practical application (chrono therapeutics)
Time that meds are taken are important for success as it indicates release
(Heart attack likely 6:00 am so meds taken before sleep to be released roughly at the right time)
Weaknesses of circadian rhythms
- individual differences (cycles vary from 13-165hrs)
-Arctic, show normal sleeping patterns
But exogenous zeitgeist of light has little influence on internal biological rhythms
- people peak differently (morning vs evening people)
- Cziesler altered someones c.rhythm down to 22hrs and 28hrs using artificial light
How long is ultradian rhythms?
Less than 24 hours
Repeats every 90 mins
What are the five stages of ultradian rhythms?
1-4: non rapid eye movement
5: rapid eye movement
What does the EEG during stage 5 of ultradian rhythms look like?
The eeg resembles an awake person where dreaming happens
What is the 90 minutes of the ultradian called?
Basic rest activity cycle
What did kleitman say about ultradian rhythms?
Applies even during the day
Stage of alertness is physiological fatigue and it happens towards the end of the ninety minutes
What is the evaluation of ultradian rhythms?
+ Ericsson studied elite violinists do 90 mins practicing then napping
They did better
It fits with BRAC
-individual differences
Pps studied for 11 days straight
Differences in when and for how long they sleep
How long are infradian rhythms?
Longer than 24 hours
Give an example of an infradian cycle
Menstrual
Strength of Infradian rhythms
+ affects behaviour
Women like more feminised male faces for LT relationships
But prefer masculine ones during ovulation
Weakness of infradian
Other factors affect periods
Women living together not taking oral contraceptives have their cycles sync
And there was a study
What was the study that disapproves infradian rhythms
Sweat of a group of females rubbed on upper lip of other females
Causing period synchronisation
Why did the two groups periods sync due to sweat?
Because of pheromones
What are pheromones?
Chemical substance released into environment that affects behaviour of others of same species
What are endrogenous pacemakers?
Internal biological rhythms
What are exogenous zeitgebers?
External cues or factors
What are EP and EZ used for?
Used to reset biological rhythms daily
What are suprachiasmatic nuclei?
Tiny cluster of nerve cells in the hypothalamus that act as a master clock to link brain regions and control all of the biological clocks in the body
How do you suprachiasmatic nuclei carry out their function?
Synchronise
Targeting neurons in other sites to get time coordinated signals
What hormone does the SCN regulate?
And how
Manufacture and secretion of melatonin in the pineal gland via an interconnecting neural pathway
It sends a signal to the gland that increases melatonin at night and it decreases it as light levels increase
Evaluation of endogenous pacemakers
+Folkard studied Kate, she spent 25 days in a lab with no access to EZ of light
Parkour temperature rhythm was at 24 hours therefore you don’t need EZ to maintain internal biological rhythms
-Kate sleep wake cycle extended to 30 hours with asleep period of 16 hours therefore we do need EZ
What are receptors in the SCN sensitive to?
Lights changes
Used to synchronise the activity of organs and glands and resets the biological clock daily
What is melanopsin?
Protein in the retina that sensitive to natural light
What does moving to the nightshift or a different time zone resulting?
EP to impose inbuilt rhythms of sleep that is out of sync with EZ of light
-disrupted sleep patterns, increased anxiety, decrease in alertness
Strengths of exogenous zeitgebers
+ Blind people with light perception have a normal circadian rhythms but those without have abnormal
+ Burgess, exposure to light prior to East West flights decrease the time needed to adjust to local time
Weakness of exogenous zeitgebers
-Arctic regions have normal sleeping pattern is so EZ has little influence on internal biological rhythms
