bio lecture 6

Question 1

What regulates sleep-wake cycles?

Answer 1

Circadian rhythms

Circadian rhythms are physiological processes that cycle every 24 hours, influencing sleep patterns.

Question 2

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how do we study sleep and what are the components?

Answer 2

polysomnograms

• • EEG (electroencephalogram)
• EOG (electro-oculogram)
• EMG (electromyogram)
• ECG (electrocardiogram)
• Airflow
• Oximeter

Polysomnograms combine these measurements to study sleep.

Question 3

What does EEG measure?

Answer 3

Brain activity

EEG captures electrical activity in the brain through electrodes placed on the scalp.

Question 4

What are the classifications of EEG waves based on frequency?

Answer 4

• Beta (β): 13-30 Hz (awake)
• Alpha (α): 8-13 Hz (relaxed, drowsy)
• Theta (θ): 3.5-7.5 Hz (light sleep)
• Delta (δ): <4 Hz (deep sleep)

EEG waves are classified by their frequency, indicating different states of consciousness.

Question 5

What characterizes Stage 1 of sleep?

Answer 5

Theta waves, transition to sleep, eyes may still be open

This stage lasts about 10 minutes, where a person may not realize they have fallen asleep.

Question 6

What are sleep spindles and K complexes associated with?

Answer 6

Stage 2 of sleep

These are specific EEG patterns that indicate deeper sleep.

Question 7

What type of brain activity is observed during REM sleep?

Answer 7

Theta and beta activity

REM sleep is characterized by brain activity similar to wakefulness, hence the term paradoxical sleep.

Question 8

What is the role of the Reticular Activating System (RAS)?

whens it active?

Answer 8

regulates wakefulnes and sleep by regulating arousal and alertness

RAS is located in the brainstem active when awake but when inhibited you fall asleep, active again in REM

Question 9

Name the five key neurotransmitters involved in wakefulness.

Answer 9

• Acetylcholine (ACh)
• Noradrenaline (NA)
• Serotonin (5-HT)
• Histamine
• Hypocretin (Orexin)

These neurotransmitters help maintain alertness and influence EEG patterns.

Question 10

What happens to acetylcholine levels during REM sleep?

Answer 10

Acetylcholine levels increase

Acetylcholine is responsible for the wake-like EEG pattern observed during REM sleep.

Question 11

What is the function of hypocretin (orexin)?

Answer 11

Regulates wakefulness and alertness

Hypocretin is involved in activating areas of the brain that promote wakefulness.

Question 12

What neurotransmitter is primarily responsible for promoting wakefulness from the Tuberomammillary Nucleus?

Answer 12

Histamine

Histamine is involved in keeping the brain awake and alert.

Question 13

inhibitiry

What is the main neurotransmitter used by the Ventrolateral Preoptic Area (vlPOA)?

Answer 13

GABA

GABA is an inhibitory neurotransmitter that helps promote sleep.

Question 14

What is the mutual inhibition system between the vlPOA and wake-promoting regions called?

Answer 14

Flip-Flop Model

This model explains the quick transitions between sleep and wakefulness.

Question 15

What are the symptoms of REM sleep?

Answer 15

• Rapid Eye Movements (REM)
• Muscle paralysis
• Penile erection/Vaginal secretion
• Clear, narrative dreams

These symptoms indicate the unique physiological state of REM sleep.

Question 16

What brain areas are involved in the REM sleep flip-flop system?

Answer 16

• Sublaterodorsal Nucleus (SLD)
• Ventrolateral Periaqueductal Gray (vlPAG)

SLD promotes REM sleep, while vlPAG inhibits it.

Question 17

During REM sleep, what neurotransmitter is predominantly active?

Answer 17

Acetylcholine

Acetylcholine activity increases during REM, contributing to the desynchronized EEG pattern.

Question 18

What happens to noradrenaline levels during REM sleep?

Answer 18

Noradrenaline levels drop

Low levels of noradrenaline are necessary for the onset of REM sleep.

Question 19

Fill in the blank: The _______ is responsible for inhibiting muscle activity during REM sleep.

Answer 19

Magnocellular nucleus

The magnocellular nucleus inhibits motor neurons to prevent movement during REM sleep.

Question 20

What activates neurons in the Tectum?

Answer 20

Rapid Eye Movements and muscle paralysis

Muscle paralysis during REM sleep is regulated by the magnocellular nucleus.

Question 21

What is the role of the magnocellular nucleus during REM sleep?

Answer 21

It inhibits motor neurons, leading to muscle paralysis

This inhibition prevents movement during REM sleep.

Question 22

What does the brain do during REM sleep?

Answer 22

Processes information as if awake and rehearses skills

The brain activates the motor cortex but inhibits muscle movement.

Question 23

Why don’t we remember dreams?

Answer 23

Certain brain parts necessary for memory are suppressed during REM sleep

This suppression hinders the formation of long-term memories.

Question 24

What are PGO Waves?

Answer 24

Activation in the Pons, Geniculate Nucleus, Occipital Cortex linked to dreaming

These waves are involved in the visual aspects of dreams.

Question 25

What is the Activation-Synthesis Hypothesis?

Answer 25

Dreams are a side effect of brain activity, creating a narrative from stimuli ## Footnote Proposed by Hobson, this theory suggests dreams lack functional purpose.

Question 26

What is the function of Slow Wave Sleep (SWS)?

Answer 26

Helps with memory consolidation and amyloid-β clearance ## Footnote This process is linked to brain recovery and prevention of Alzheimer’s.

Question 27

What are the three types of external input that change the flip-flop and cause transition?

Answer 27

Homeostatic, Allostatic, Circadian Control ## Footnote These inputs influence sleep regulation and cycles.

Question 28

What accumulates in the brain as the day progresses and leads to sleepiness?

Answer 28

Adenosine ## Footnote It is a by-product of glucose metabolism and inhibits neuronal firing.

Question 29

How does caffeine affect sleep?

Answer 29

Blocks adenosine receptors, keeping you more awake ## Footnote This prevents the inhibitory effects of adenosine on the brain.

Question 30

What is the Allostatic Control in sleep regulation?

Answer 30

Overrides sleep need due to stress or survival threats ## Footnote It prioritizes immediate needs over the body's sleep requirements.

Question 31

What hormones influence hypocretinergic neurons?

Answer 31

Leptin and ghrelin ## Footnote Leptin signals fullness, while ghrelin signals hunger, affecting sleepiness.

Question 32

What does Circadian Control regulate?

Answer 32

Sleep relative to the day-night cycle ## Footnote This control persists even without external cues, indicating an internal biological clock.

Question 33

What is the role of the Suprachiasmatic Nucleus (SCN)?

Answer 33

Acts as a biological clock, maintaining a 24-hour rhythm ## Footnote It is essential for synchronizing circadian rhythms.

Question 34

What happens to the sleep-wake cycle if the SCN is damaged?

Answer 34

The cycle becomes less organized, leading to ultradian rhythms ## Footnote This was observed in hamster studies where SCN damage altered sleep patterns.

Question 35

What are the core components of the molecular mechanisms in the SCN?

Answer 35

Period genes (perl-3), cryptochrome genes (cry1-2), Clock and Bmal1 genes ## Footnote These genes are crucial for maintaining circadian rhythms.

Question 36

What does the transcription-translation feedback loop in SCN neurons involve?

Answer 36

Clock and Bmal1 stimulate transcription of Cry and Per genes, which then inhibit Clock and Bmal1 ## Footnote This creates a negative feedback loop regulating circadian rhythms.

Question 37

What effect does light have on the SCN?

Answer 37

It activates SCN neurons, altering mRNA levels and shifting circadian cycles ## Footnote Light during subjective night can pull mRNA levels up earlier than usual.

Question 38

What are retinal ganglion cells and their role in light detection?

Answer 38

They contain melanopsin and synapse directly onto SCN neurons ## Footnote These cells allow synchronization of the circadian clock with external light conditions.

Question 39

How does the body respond to light exposure during subjective night?

Answer 39

It increases mRNA levels, shifting the circadian cycle ## Footnote This can lead to changes in the timing of biological processes.

Question 40

What is the significance of zeitgebers?

Answer 40

External cues that help synchronize circadian rhythms ## Footnote Examples include light, food, and sounds.

Question 41

What happens to mRNA levels during the subjective day with light exposure?

Answer 41

There is no significant change, as levels are already increasing ## Footnote The internal clock is less affected during this period.

Question 42

What occurs when light is exposed during the early to late night?

Answer 42

It delays the circadian rhythm ## Footnote This can lead to a lengthening of the circadian cycle.

Question 43

What effect does light have on the transcription process during subjective day?

Answer 43

No difference.

Question 44

What happens to transcription when light is given during subjective night?

Answer 44

Transcription occurs when you weren't expecting it.

Question 45

What is the effect of light given during early to late night on circadian rhythm?

Answer 45

Delays (lengthens) the circadian rhythm.

Question 46

What is the effect of light given in the early morning on the biological clock?

Answer 46

Advances (shortens) the clock.

Question 47

What type of light is most effective in resetting the biological clock?

Answer 47

Blue light.

Question 48

What is the role of melanopsin in relation to light?

Answer 48

It has a peak response in the blue range, making it most sensitive for resetting the clock.

Question 49

What hormone is released by the pineal gland?

Answer 49

Melatonin.

Question 50

How does the SCN influence melatonin release?

Answer 50

SCN activity during subjective day inhibits melatonin release.

Question 51

What happens to melatonin production during subjective night?

Answer 51

Production of melatonin into the blood occurs.

Question 52

What is the function of melatonin in relation to the SCN?

Answer 52

It feeds back to the SCN and can shift the biological clock.

Question 53

What is homeostatic control in sleep regulation?

Answer 53

Accumulation of adenosine.

Question 54

What are the three types of sleep regulation mentioned?

Answer 54

Homeostatic, allostatic, circadian.

Question 55

What is insomnia?

Answer 55

Inability to fall asleep.

Question 56

What is a common cause of insomnia?

Answer 56

Sleep Apnea.

Question 57

What is narcolepsy characterized by?

Answer 57

Sudden sleep attacks.

Question 58

What is cataplexy?

Answer 58

Sleep attack without falling asleep, experiencing paralysis of REM sleep.

Question 59

What is sleep paralysis?

Answer 59

Occurs during normal transition to sleep, experienced in bed.

Question 60

What are hypnagogic hallucinations?

Answer 60

Awake but experiencing mixing of dreams and reality.

Question 61

What is the REM Sleep Behaviour Disorder?

Answer 61

Acting out dreams due to lack of paralysis in REM.

Question 62

What disorders are classified under Slow Wave Sleep Disorders?

Answer 62

Sleepwalking, night terrors, bedwetting.

Question 63

What is jet lag?

Answer 63

Internal clock misalignment due to time zone changes.

Question 64

How can jet lag be treated?

Answer 64

With melatonin.

Question 65

What is a rule of thumb for exposing oneself to light when experiencing jet lag?

Answer 65

Expose yourself to light outside if the internal clock thinks it's night.

Question 66

What are the molecular mechanisms that regulate biological rhythms?

Answer 66

Period (Per1-3), Cryptochrome (Cry1-2), Clock & Bmal1 genes.